title: "Boeing 767" content: the 777, a larger wide-body twinjet. In the 1990s, the 767 became the most frequently used airliner for transatlantic flights between North America and Europe. The 767 is the first twinjet wide-body type to reach 1,000 aircraft delivered. , Boeing has received 1,224 orders for the 767 from 74 customers with 1,118 delivered. A total of 742 of these aircraft were in service in July 2018. The most popular variant is the 767-300ER with 583 delivered. Delta Air Lines is the largest operator with 77 aircraft. Competitors have included the Airbus A300, A310, and A330-200. Non-passenger variants of the 767


title: "Boeing 767" content: remain in production while the passenger variant's successor, the 787, entered service in 2011. In 1970, Boeing's 747 became the first wide-body jetliner to enter service. The 747 was the first passenger jet wide enough to feature a twin-aisle cabin. Two years later, the manufacturer began a development study, code-named 7X7, for a new wide-body aircraft intended to replace the 707 and other early generation narrow-body jets. The aircraft would also provide twin-aisle seating, but in a smaller fuselage than the existing 747, McDonnell Douglas DC-10, and Lockheed L-1011 TriStar wide-bodies. To defray the high cost of development, Boeing signed


title: "Boeing 767" content: risk-sharing agreements with Italian corporation Aeritalia and the Civil Transport Development Corporation (CTDC), a consortium of Japanese aerospace companies. This marked the manufacturer's first major international joint venture, and both Aeritalia and the CTDC received supply contracts in return for their early participation. The initial 7X7 was conceived as a short take-off and landing airliner intended for short-distance flights, but customers were unenthusiastic about the concept, leading to its redefinition as a mid-size, transcontinental-range airliner. At this stage the proposed aircraft featured two or three engines, with possible configurations including over-wing engines and a T-tail. By 1976, a twinjet layout,


title: "Boeing 767" content: similar to the one which had debuted on the Airbus A300, became the baseline configuration. The decision to use two engines reflected increased industry confidence in the reliability and economics of new-generation jet powerplants. While airline requirements for new wide-body aircraft remained ambiguous, the 7X7 was generally focused on mid-size, high-density markets. As such, it was intended to transport large numbers of passengers between major cities. Advancements in civil aerospace technology, including high-bypass-ratio turbofan engines, new flight deck systems, aerodynamic improvements, and lighter construction materials were to be applied to the 7X7. Many of these features were also included in


title: "Boeing 767" content: a parallel development effort for a new mid-size narrow-body airliner, code-named 7N7, which would become the 757. Work on both proposals proceeded through the airline industry upturn in the late 1970s. In January 1978, Boeing announced a major extension of its Everett factory—which was then dedicated to manufacturing the 747—to accommodate its new wide-body family. In February 1978, the new jetliner received the 767 model designation, and three variants were planned: a 767-100 with 190 seats, a 767-200 with 210 seats, and a trijet 767MR/LR version with 200 seats intended for intercontinental routes. The 767MR/LR was subsequently renamed 777 for


title: "Boeing 767" content: differentiation purposes. The 767 was officially launched on July 14, 1978, when United Airlines ordered 30 of the 767-200 variant, followed by 50 more 767-200 orders from American Airlines and Delta Air Lines later that year. The 767-100 was ultimately not offered for sale, as its capacity was too close to the 757's seating, while the 777 trijet was eventually dropped in favor of standardizing around the twinjet configuration. In the late 1970s, operating cost replaced capacity as the primary factor in airliner purchases. As a result, the 767's design process emphasized fuel efficiency from the outset. Boeing targeted a


title: "Boeing 767" content: 20 to 30 percent cost saving over earlier aircraft, mainly through new engine and wing technology. As development progressed, engineers used computer-aided design for over a third of the 767's design drawings, and performed 26,000 hours of wind tunnel tests. Design work occurred concurrently with the 757 twinjet, leading Boeing to treat both as almost one program to reduce risk and cost. Both aircraft would ultimately receive shared design features, including avionics, flight management systems, instruments, and handling characteristics. Combined development costs were estimated at $3.5 to $4 billion. Early 767 customers were given the choice of Pratt & Whitney


title: "Boeing 767" content: JT9D or General Electric CF6 turbofans, marking the first time that Boeing had offered more than one engine option at the launch of a new airliner. Both jet engine models had a maximum output of of thrust. The engines were mounted approximately one-third the length of the wing from the fuselage, similar to previous wide-body trijets. The larger wings were designed using an aft-loaded shape which reduced aerodynamic drag and distributed lift more evenly across their surface span than any of the manufacturer's previous aircraft. The wings provided higher-altitude cruise performance, added fuel capacity, and expansion room for future stretched


title: "Boeing 767" content: variants. The initial 767-200 was designed for sufficient range to fly across North America or across the northern Atlantic, and would be capable of operating routes up to . The 767's fuselage width was set midway between that of the 707 and the 747 at . While it was narrower than previous wide-body designs, seven abreast seating with two aisles could be fitted, and the reduced width produced less aerodynamic drag. The fuselage was not wide enough to accommodate two standard LD3 wide-body unit load devices side-by-side, so a smaller container, the LD2, was created specifically for the 767. Using


title: "Boeing 767" content: a conventional tail design also allowed the rear fuselage to be tapered over a shorter section, providing for parallel aisles along the full length of the passenger cabin, and eliminating irregular seat rows toward the rear of the aircraft. The 767 was the first Boeing wide-body to be designed with a two-crew digital glass cockpit. Cathode ray tube (CRT) color displays and new electronics replaced the role of the flight engineer by enabling the pilot and co-pilot to monitor aircraft systems directly. Despite the promise of reduced crew costs, United Airlines initially demanded a conventional three-person cockpit, citing concerns about


title: "Boeing 767" content: the risks associated with introducing a new aircraft. The carrier maintained this position until July 1981, when a US presidential task force determined that a crew of two was safe for operating wide-body jets. A three-crew cockpit remained as an option and was fitted to the first production models. Ansett Australia ordered 767s with three-crew cockpits due to union demands; it was the only airline to operate 767s so configured. The 767's two-crew cockpit was also applied to the 757, allowing pilots to operate both aircraft after a short conversion course, and adding incentive for airlines to purchase both types.


title: "Boeing 767" content: Although nominally similar in control design, flying the 767 feels different from the 757. The 757's controls are heavy, similar to the 727 and 747; the control yoke can be rotated to 90 degrees in each direction. The 767 has far lighter control feel in pitch and roll, and the control yoke has approximately 2/3 the rotation travel. To produce the 767, Boeing formed a network of subcontractors which included domestic suppliers and international contributions from Italy's Aeritalia and Japan's CTDC. The wings and cabin floor were produced in-house, while Aeritalia provided control surfaces, Boeing Vertol made the leading edge


title: "Boeing 767" content: for the wings, and Boeing Wichita produced the forward fuselage. The CTDC provided multiple assemblies through its constituent companies, namely Fuji Heavy Industries (wing fairings and gear doors), Kawasaki Heavy Industries (center fuselage), and Mitsubishi Heavy Industries (rear fuselage, doors, and tail). Components were integrated during final assembly at the Everett factory. For expedited production of wing spars, the main structural member of aircraft wings, the Everett factory received robotic machinery to automate the process of drilling holes and inserting fasteners. This method of wing construction expanded on techniques developed for the 747. Final assembly of the first aircraft began


title: "Boeing 767" content: in July 1979. The prototype aircraft, registered N767BA and equipped with JT9D turbofans, rolled out on August 4, 1981. By this time, the 767 program had accumulated 173 firm orders from 17 customers, including Air Canada, All Nippon Airways, Britannia Airways, Transbrasil, and Trans World Airlines (TWA). On September 26, 1981, the prototype took its maiden flight under the command of company test pilots Tommy Edmonds, Lew Wallick, and John Brit. The maiden flight was largely uneventful, save for the inability to retract the landing gear because of a hydraulic fluid leak. The prototype was used for subsequent flight tests.


title: "Boeing 767" content: The 10-month 767 flight test program utilized the first six aircraft built. The first four aircraft were equipped with JT9D engines, while the fifth and sixth were fitted with CF6 engines. The test fleet was largely used to evaluate avionics, flight systems, handling, and performance, while the sixth aircraft was used for route-proving flights. During testing, pilots described the 767 as generally easy to fly, with its maneuverability unencumbered by the bulkiness associated with larger wide-body jets. Following 1,600 hours of flight tests, the JT9D-powered 767-200 received certification from the US Federal Aviation Administration (FAA) and the UK Civil Aviation


title: "Boeing 767" content: Authority (CAA) in July 1982. The first delivery occurred on August 19, 1982, to United Airlines. The CF6-powered 767-200 received certification in September 1982, followed by the first delivery to Delta Air Lines on October 25, 1982. The 767 entered service with United Airlines on September 8, 1982. The aircraft's first commercial flight used a JT9D-powered 767-200 on the Chicago-to-Denver route. The CF6-powered 767-200 commenced service three months later with Delta Air Lines. Upon delivery, early 767s were mainly deployed on domestic routes, including US transcontinental services. American Airlines and TWA began flying the 767-200 in late 1982, while Air


title: "Boeing 767" content: Canada, China Airlines, and El Al began operating the aircraft in 1983. The aircraft's introduction was relatively smooth, with few operational glitches and greater dispatch reliability than prior jetliners. In its first year, the 767 logged a 96.1 percent dispatch rate, which exceeded the industry average for new aircraft. Operators reported generally favorable ratings for the twinjet's sound levels, interior comfort, and economic performance. Resolved issues were minor and included the recalibration of a leading edge sensor to prevent false readings, the replacement of an evacuation slide latch, and the repair of a tailplane pivot to match production specifications. Seeking


title: "Boeing 767" content: to capitalize on its new wide-body's potential for growth, Boeing offered an extended-range model, the 767-200ER, in its first year of service. Ethiopian Airlines placed the first order for the type in December 1982. Featuring increased gross weight and greater fuel capacity, the extended-range model could carry heavier payloads at distances up to , and was targeted at overseas customers. The 767-200ER entered service with El Al Airline on March 27, 1984. The type was mainly ordered by international airlines operating medium-traffic, long-distance flights. In the mid-1980s, the 767 spearheaded the growth of twinjet flights across the northern Atlantic under


title: "Boeing 767" content: extended-range twin-engine operational performance standards (ETOPS) regulations, the FAA's safety rules governing transoceanic flights by aircraft with two engines. Before the 767, overwater flight paths of twinjets could be no more than 90 minutes away from diversion airports. In May 1985, the FAA granted its first approval for 120-minute ETOPS flights to 767 operators, on an individual airline basis starting with TWA, provided that the operator met flight safety criteria. This allowed the aircraft to fly overseas routes at up to two hours' distance from land. The larger safety margins were permitted because of the improved reliability demonstrated by the


title: "Boeing 767" content: twinjet and its turbofan engines. The FAA lengthened the ETOPS time to 180 minutes for CF6-powered 767s in 1989, making the type the first to be certified under the longer duration, and all available engines received approval by 1993. Regulatory approval spurred the expansion of transoceanic 767 flights and boosted the aircraft's sales. Forecasting airline interest in larger-capacity models, Boeing announced the stretched 767-300 in 1983 and the extended-range 767-300ER in 1984. Both models offered a 20 percent passenger capacity increase, while the extended-range version was capable of operating flights up to . Japan Airlines placed the first order for


title: "Boeing 767" content: the 767-300 in September 1983. Following its first flight on January 30, 1986, the type entered service with Japan Airlines on October 20, 1986. The 767-300ER completed its first flight on December 9, 1986, but it was not until March 1987 that the first firm order, from American Airlines, was placed. The type entered service with American Airlines on March 3, 1988. The 767-300 and 767-300ER gained popularity after entering service, and came to account for approximately two-thirds of all 767s sold. After the debut of the first stretched 767s, Boeing sought to address airline requests for greater capacity by


title: "Boeing 767" content: proposing larger models, including a partial double-deck version informally named the "Hunchback of Mukilteo" (from a town near Boeing's Everett factory) with a 757 body section mounted over the aft main fuselage. In 1986, Boeing proposed the 767-X, a revised model with extended wings and a wider cabin, but received little interest. By 1988, the 767-X had evolved into an all-new twinjet, which revived the 777 designation. Until the 777's 1995 debut, the 767-300 and 767-300ER remained Boeing's second-largest wide-bodies behind the 747. Buoyed by a recovering global economy and ETOPS approval, 767 sales accelerated in the mid-to-late 1980s; 1989


title: "Boeing 767" content: was the most prolific year with 132 firm orders. By the early 1990s, the wide-body twinjet had become its manufacturer's annual best-selling aircraft, despite a slight decrease due to economic recession. During this period, the 767 became the most common airliner for transatlantic flights between North America and Europe. By the end of the decade, 767s crossed the Atlantic more frequently than all other aircraft types combined. The 767 also propelled the growth of point-to-point flights which bypassed major airline hubs in favor of direct routes. Taking advantage of the aircraft's lower operating costs and smaller capacity, operators added non-stop


title: "Boeing 767" content: flights to secondary population centers, thereby eliminating the need for connecting flights. The increased number of cities receiving non-stop services caused a paradigm shift in the airline industry as point-to-point travel gained prominence at the expense of the traditional hub-and-spoke model. In February 1990, the first 767 equipped with Rolls-Royce RB211 turbofans, a 767-300, was delivered to British Airways. Six months later, the carrier temporarily grounded its entire 767 fleet after discovering cracks in the engine pylons of several aircraft. The cracks were related to the extra weight of the RB211 engines, which are heavier than other 767 engines. During


title: "Boeing 767" content: the grounding, interim repairs were conducted to alleviate stress on engine pylon components, and a parts redesign in 1991 prevented further cracks. Boeing also performed a structural reassessment, resulting in production changes and modifications to the engine pylons of all 767s in service. In January 1993, following an order from UPS Airlines, Boeing launched a freighter variant, the 767-300F, which entered service with UPS on October 16, 1995. The 767-300F featured a main deck cargo hold, upgraded landing gear, and strengthened wing structure. In November 1993, the Japanese government launched the first 767 military derivative when it placed orders for


title: "Boeing 767" content: the , an Airborne Early Warning and Control (AWACS) variant based on the 767-200ER. The first two , featuring extensive modifications to accommodate surveillance radar and other monitoring equipment, were delivered in 1998 to the Japan Self-Defense Forces. In November 1995, after abandoning development of a smaller version of the 777, Boeing announced that it was revisiting studies for a larger 767. The proposed 767-400X, a second stretch of the aircraft, offered a 12 percent capacity increase versus the 767-300, and featured an upgraded flight deck, enhanced interior, and greater wingspan. The variant was specifically aimed at Delta Air Lines'


title: "Boeing 767" content: pending replacement of its aging Lockheed L-1011 TriStars, and faced competition from the A330-200, a shortened derivative of the Airbus A330. In March 1997, Delta Air Lines launched the 767-400ER when it ordered the type to replace its L-1011 fleet. In October 1997, Continental Airlines also ordered the 767-400ER to replace its McDonnell Douglas DC-10 fleet. The type completed its first flight on October 9, 1999, and entered service with Continental Airlines on September 14, 2000. In the early 2000s, cumulative 767 deliveries approached 900, but new sales declined during an airline industry downturn. In 2001, Boeing dropped plans for


title: "Boeing 767" content: a longer-range model, the 767-400ERX, in favor of the proposed Sonic Cruiser, a new jetliner which aimed to fly 15 percent faster while having comparable fuel costs as the 767. The following year, Boeing announced the KC-767 Tanker Transport, a second military derivative of the 767-200ER. Launched with an order in October 2002 from the Italian Air Force, the KC-767 was intended for the dual role of refueling other aircraft and carrying cargo. The Japanese government became the second customer for the type in March 2003. In May 2003, the United States Air Force (USAF) announced its intent to lease


title: "Boeing 767" content: KC-767s to replace its aging KC-135 tankers. The plan was suspended in March 2004 amid a conflict of interest scandal, resulting in multiple US government investigations and the departure of several Boeing officials, including Philip Condit, the company's chief executive officer, and chief financial officer Michael Sears. The first KC-767s were delivered in 2008 to the Japan Self-Defense Forces. In late 2002, after airlines expressed reservations about its emphasis on speed over cost reduction, Boeing halted development of the Sonic Cruiser. The following year, the manufacturer announced the 7E7, a mid-size 767 successor made from composite materials which promised to


title: "Boeing 767" content: be 20 percent more fuel efficient. The new jetliner was the first stage of a replacement aircraft initiative called the Boeing Yellowstone Project. Customers embraced the 7E7, later renamed 787 Dreamliner, and within two years it had become the fastest-selling airliner in the company's history. In 2005, Boeing opted to continue 767 production despite record Dreamliner sales, citing a need to provide customers waiting for the 787 with a more readily available option. Subsequently, the 767-300ER was offered to customers affected by 787 delays, including All Nippon Airways and Japan Airlines. Some aging 767s, exceeding 20 years in age, were


title: "Boeing 767" content: also kept in service past planned retirement dates due to the delays. To extend the operational lives of older aircraft, airlines increased heavy maintenance procedures, including D-check teardowns and inspections for corrosion, a recurring issue on aging 767s. The first 787s entered service with All Nippon Airways in October 2011, 42 months behind schedule. In 2007, the 767 received a production boost when UPS and DHL Aviation placed a combined 33 orders for the 767-300F. Renewed freighter interest led Boeing to consider enhanced versions of the 767-200 and 767-300F with increased gross weights, 767-400ER wing extensions, and 777 avionics. Net


title: "Boeing 767" content: orders for the 767 declined from 24 in 2008 to just three in 2010. During the same period, operators upgraded aircraft already in service; in 2008, the first 767-300ER retrofitted with blended winglets from Aviation Partners Incorporated debuted with American Airlines. The manufacturer-sanctioned winglets, at in height, improved fuel efficiency by an estimated 6.5 percent. Other carriers including All Nippon Airways and Delta Air Lines also ordered winglet kits. On February 2, 2011, the 1,000th 767 rolled out, destined for All Nippon Airways. The aircraft was the 91st 767-300ER ordered by the Japanese carrier, and with its completion the 767


title: "Boeing 767" content: became the second wide-body airliner to reach the thousand-unit milestone after the 747. The 1,000th aircraft also marked the last model produced on the original 767 assembly line. Beginning with the 1,001st aircraft, production moved to another area in the Everett factory which occupied about half of the previous floor space. The new assembly line made room for 787 production and aimed to boost manufacturing efficiency by over twenty percent. At the inauguration of its new assembly line, the 767's order backlog numbered approximately 50, only enough for production to last until 2013. Despite the reduced backlog, Boeing officials expressed


title: "Boeing 767" content: optimism that additional orders would be forthcoming. On February 24, 2011, the USAF announced its selection of the KC-767 Advanced Tanker, an upgraded variant of the KC-767, for its KC-X fleet renewal program. The selection followed two rounds of tanker competition between Boeing and Airbus parent EADS, and came eight years after the USAF's original 2003 announcement of its plan to lease KC-767s. The tanker order encompassed 179 aircraft and was expected to sustain 767 production past 2013. In December 2011, FedEx Express announced a 767-300F order for 27 aircraft to replace its DC-10 freighters, citing the USAF tanker order


title: "Boeing 767" content: and Boeing's decision to continue production as contributing factors. FedEx Express agreed to buy 19 more of the −300F variant in June 2012. In June 2015, FedEx said it was accelerating retirements of planes both to reflect demand and to modernize its fleet, recording charges of $276 million. On July 21, 2015 FedEx announced an order for 50 767-300F with options on another 50, the largest order for the type. With the announcement FedEx confirmed that it has firm orders for 106 of the freighters for delivery between 2018 and 2023. In February 2018, UPS announced that they were ordering


title: "Boeing 767" content: 4 more 767-300Fs, increasing their total order to 63. Deliveries are scheduled from 2017 through 2022. With its successor, the Boeing New Midsize Airplane, planned for at least a 2025 introduction, and the 787 being much larger, Boeing could restart a passenger 767-300ER production to bridge the gap. A demand for 50 to 60 aircraft could have to be satisfied. Having to replace its 40 767s, United Airlines requested a price quote for other widebodies. In November 2017, Boeing CEO Dennis Muilenburg cited interest beyond military and freighter uses. Boeing Commercial Airplanes VP of marketing Randy Tinseth stated in early


title: "Boeing 767" content: 2018 that the company did not intend to resume passenger variant production. In its first quarter of 2018 earnings report, Boeing plan to increase its production from 2.5 to 3 monthly beginning in January 2020 due to increased demand in the cargo market, as FedEx had 56 on order, UPS has four, and an unidentified customer has three on order. This rate could rise to 3.5 per month in July 2020 and 4 per month in January 2021, then would come down to 3 per month in January 2025 and 2 per month in July. The 767 is a low-wing


title: "Boeing 767" content: cantilever monoplane with a conventional tail unit featuring a single fin and rudder. The wings are swept at 31.5 degrees and optimized for a cruising speed of Mach 0.8 (). Each wing features a supercritical airfoil cross-section and is equipped with six-panel leading edge slats, single- and double-slotted flaps, inboard and outboard ailerons, and six spoilers. The airframe further incorporates Carbon-fiber-reinforced polymer composite material wing surfaces, Kevlar fairings and access panels, plus improved aluminum alloys, which together reduce overall weight by versus preceding aircraft. To distribute the aircraft's weight on the ground, the 767 has a retractable tricycle landing gear


title: "Boeing 767" content: with four wheels on each main gear and two for the nose gear. The original wing and gear design accommodated the stretched 767-300 without major changes. The 767-400ER features a larger, more widely spaced main gear with 777 wheels, tires, and brakes. To prevent damage if the tail section contacts the runway surface during takeoff, 767-300 and 767-400ER models are fitted with a retractable tailskid. The 767 has left-side exit doors near the front and rear of the aircraft. In addition to shared avionics and computer technology, the 767 uses the same auxiliary power unit, electric power systems, and hydraulic


title: "Boeing 767" content: parts as the 757. A raised cockpit floor and the same forward cockpit windows result in similar pilot viewing angles. Related design and functionality allows 767 pilots to obtain a common type rating to operate the 757 and share the same seniority roster with pilots of either aircraft. The original 767 flight deck uses six Rockwell Collins CRT screens to display Electronic flight instrument system (EFIS) and engine indication and crew alerting system (EICAS) information, allowing pilots to handle monitoring tasks previously performed by the flight engineer. The CRTs replace conventional electromechanical instruments found on earlier aircraft. An enhanced flight


title: "Boeing 767" content: management system, improved over versions used on early 747s, automates navigation and other functions, while an automatic landing system facilitates CAT IIIb instrument landings in low visibility situations. The 767 became the first aircraft to receive CAT IIIb certification from the FAA for landings with minimum visibility in 1984. On the 767-400ER, the cockpit layout is simplified further with six Rockwell Collins liquid crystal display (LCD) screens, and adapted for similarities with the 777 and the Next Generation 737. To retain operational commonality, the LCD screens can be programmed to display information in the same manner as earlier 767s. In


title: "Boeing 767" content: 2012, Boeing and Rockwell Collins launched a further 787-based cockpit upgrade for the 767, featuring three landscape-format LCD screens that can display two windows each. The 767 is equipped with three redundant hydraulic systems for operation of control surfaces, landing gear, and utility actuation systems. Each engine powers a separate hydraulic system, and the third system uses electric pumps. A ram air turbine provides power for basic controls in the event of an emergency. An early form of fly-by-wire is employed for spoiler operation, utilizing electric signaling instead of traditional control cables. The fly-by-wire system reduces weight and allows independent


title: "Boeing 767" content: operation of individual spoilers. The 767 features a twin-aisle cabin with a typical configuration of six abreast in business class and seven across in economy. The standard seven abreast, 2–3–2 economy class layout places approximately 87 percent of all seats at a window or aisle. As a result, the aircraft can be largely occupied before center seats need to be filled, and each passenger is no more than one seat from the aisle. It is possible to configure the aircraft with extra seats for up to an eight abreast configuration, but this is less common. The 767 interior introduced larger


title: "Boeing 767" content: overhead bins and more lavatories per passenger than previous aircraft. The bins are wider to accommodate garment bags without folding, and strengthened for heavier carry-on items. A single, large galley is installed near the aft doors, allowing for more efficient meal service and simpler ground resupply. Passenger and service doors are an overhead plug type, which retract upwards, and commonly used doors can be equipped with an electric-assist system. In 2000, a 777-style interior, known as the Boeing Signature Interior, debuted on the 767-400ER. Subsequently, adopted for all new-build 767s, the Signature Interior features even larger overhead bins, indirect lighting,


title: "Boeing 767" content: and sculpted, curved panels. The 767-400ER also received larger windows derived from the 777. Older 767s can be retrofitted with the Signature Interior. Some operators have adopted a simpler modification known as the Enhanced Interior, featuring curved ceiling panels and indirect lighting with minimal modification of cabin architecture, as well as aftermarket modifications such as the NuLook 767 package by Heath Tecna. The 767 has been produced in three fuselage lengths. These debuted in progressively larger form as the 767-200, 767-300, and 767-400ER. Longer-range variants include the 767-200ER and 767-300ER, while cargo models include the 767-300F, a production freighter, and


title: "Boeing 767" content: conversions of passenger 767-200 and 767-300 models. When referring to different variants, Boeing and airlines often collapse the model number (767) and the variant designator (e.g. –200 or –300) into a truncated form (e.g. "762" or "763"). Subsequent to the capacity number, designations may append the range identifier. The International Civil Aviation Organization (ICAO) aircraft type designator system uses a similar numbering scheme, but adds a preceding manufacturer letter; all variants based on the 767-200 and 767-300 are classified under the codes "B762" and "B763"; the 767-400ER receives the designation of "B764". The 767-200 was the original model and entered


title: "Boeing 767" content: service with United Airlines in 1982. The type has been used primarily by mainline U.S. carriers for domestic routes between major hub centers such as Los Angeles to Washington. The 767-200 was the first aircraft to be used on transatlantic ETOPS flights, beginning with TWA on February 1, 1985 under 90-minute diversion rules. Deliveries for the variant totaled 128 aircraft. There were 52 passenger and freighter conversions of the model in commercial service . The type's competitors included the Airbus A300 and A310. The 767-200 ceased production in the late 1980s, superseded by the extended-range 767-200ER. Some early 767-200s were


title: "Boeing 767" content: subsequently upgraded to extended-range specification. In 1998, Boeing began offering 767-200 conversions to 767-200SF (Special Freighter) specification for cargo use, and Israel Aerospace Industries has been licensed to perform cargo conversions since 2005. The conversion process entails the installation of a side cargo door, strengthened main deck floor, and added freight monitoring and safety equipment. The 767-200SF was positioned as a replacement for Douglas DC-8 freighters. A commercial freighter version of the Boeing 767-200 with wings from the -300 series and an updated flightdeck was first flown on 29 December 2014. A military tanker variant of the Boeing 767-2C is


title: "Boeing 767" content: being developed for the USAF as the KC-46. Boeing is building two aircraft as commercial freighters which will be used to obtain Federal Aviation Administration certification, a further two Boeing 767-2Cs will be modified as military tankers. , Boeing does not have customers for the freighter. The 767-200ER was the first extended-range model and entered service with El Al in 1984. The type's increased range is due to an additional center fuel tank and a higher maximum takeoff weight (MTOW) of up to . The type was originally offered with the same engines as the 767-200, while more powerful Pratt


title: "Boeing 767" content: & Whitney PW4000 and General Electric CF6 engines later became available. The 767-200ER was the first 767 to complete a non-stop transatlantic journey, and broke the flying distance record for a twinjet airliner on April 17, 1988 with an Air Mauritius flight from Halifax, Nova Scotia to Port Louis, Mauritius, covering . The 767-200ER has been acquired by international operators seeking smaller wide-body aircraft for long-haul routes such as New York to Beijing. Deliveries of the type totaled 121 with no unfilled orders. As of July 2018, 21 examples of passenger and freighter conversion versions were in airline service. The


title: "Boeing 767" content: type's main competitors of the time included the Airbus A300-600R and the A310-300. The 767-300, the first stretched version of the aircraft, entered service with Japan Airlines in 1986. The type features a fuselage extension over the 767-200, achieved by additional sections inserted before and after the wings, for an overall length of . Reflecting the growth potential built into the original 767 design, the wings, engines, and most systems were largely unchanged on the 767-300. An optional mid-cabin exit door is positioned ahead of the wings on the left, while more powerful Pratt & Whitney PW4000 and Rolls-Royce RB211


title: "Boeing 767" content: engines later became available. The 767-300's increased capacity has been used on high-density routes within Asia and Europe. Deliveries for the type totaled 104 aircraft with no unfilled orders remaining. As of July 2018, 34 of the variant were in airline service. The type's main competitor was the Airbus A300. The 767-300ER, the extended-range version of the 767-300, entered service with American Airlines in 1988. The type's increased range was made possible by greater fuel tankage and a higher MTOW of . Design improvements allowed the available MTOW to increase to by 1993. Power is provided by Pratt & Whitney


title: "Boeing 767" content: PW4000, General Electric CF6, or Rolls-Royce RB211 engines. the 767-300ER comes in three exit configurations: the baseline configuration has four main cabin doors and four over-wing window exits, the second configuration has six main cabin doors and two over-wing window exits; and the third configuration has six main cabin doors, as well as two smaller doors that are located behind the wings. Typical routes for the type include Los Angeles to Frankfurt. The combination of increased capacity and range offered by the 767-300ER has been particularly attractive to both new and existing 767 operators. It is the most successful version


title: "Boeing 767" content: of the aircraft, with more orders placed than all other variants combined. , 767-300ER deliveries stand at 583 with no unfilled orders. There were 376 examples in service . The type's main competitor is the Airbus A330-200. At its 1990s peak, a new 767-300ER was valued at $85 million, dipping to around $12 million in 2018 for a 1996 build. The 767-300F, the production freighter version of the 767-300ER, entered service with UPS Airlines in 1995. The 767-300F can hold up to 24 standard pallets on its main deck and up to 30 LD2 unit load devices on the lower


title: "Boeing 767" content: deck, with a total cargo volume of . The freighter has a main deck cargo door and crew exit, while the lower deck features two port-side cargo doors and one starboard cargo door. A general market version with onboard freight-handling systems, refrigeration capability, and crew facilities was delivered to Asiana Airlines on August 23, 1996. , 767-300F deliveries stand at 144 with 68 unfilled orders. Airlines operated 222 examples of the freighter variant and freighter conversions in July 2018. In June 2008, All Nippon Airways took delivery of the first 767-300BCF (Boeing Converted Freighter), a modified passenger-to-freighter model. The conversion


title: "Boeing 767" content: work was performed in Singapore by ST Aerospace Services, the first supplier to offer a 767-300BCF program, and involved the addition of a main deck cargo door, strengthened main deck floor, and additional freight monitoring and safety equipment. Since then, Boeing, Israel Aerospace Industries, and Wagner Aeronautical have also offered passenger-to-freighter conversion programs for 767-300 series aircraft. The 767-400ER, the first Boeing wide-body jet resulting from two fuselage stretches, entered service with Continental Airlines in 2000. The type features a stretch over the 767-300, for a total length of . The wingspan is also increased by through the addition of


title: "Boeing 767" content: raked wingtips. The exit configuration uses six main cabin doors and two smaller exit doors behind the wings, similar to certain 767-300ER's. Other differences include an updated cockpit, redesigned landing gear, and 777-style Signature Interior. Power is provided by uprated Pratt & Whitney PW4000 or General Electric CF6 engines. The FAA granted approval for the 767-400ER to operate 180-minute ETOPS flights before it entered service. Because its fuel capacity was not increased over preceding models, the 767-400ER has a range of , less than previous extended-range 767s. This is roughly the distance from Shenzhen to Seattle. No 767-400 version was


title: "Boeing 767" content: developed, while a longer-range version, the 767-400ERX, was offered for sale in 2000 before it was cancelled a year later, leaving the 767-400ER as the sole version of the largest 767. Boeing dropped the 767-400ER and the -200ER from its pricing list in 2014. A total of 37 aircraft were delivered to the variant's two airline customers, Continental Airlines (now merged with United Airlines) and Delta Air Lines, with no unfilled orders. All 37 examples of the -400ER were in service in July 2018. One additional example was produced as a military testbed, and later sold as a VIP transport.


title: "Boeing 767" content: The type's closest competitor is the Airbus A330-200. Versions of the 767 serve in a number of military and government applications, with responsibilities ranging from airborne surveillance and refueling to cargo and VIP transport. Several military 767s have been derived from the 767-200ER, the longest-range version of the aircraft. Boeing offered the 767-400ERX, a longer-range version of the largest 767 model, in 2000. Introduced concurrently with the 747X, the type was to be powered by the 747X's engines, the Engine Alliance GP7000 and the Rolls-Royce Trent 600. An increased range of was specified. Kenya Airways provisionally ordered three 767-400ERXs to


title: "Boeing 767" content: supplement its 767 fleet, but after Boeing cancelled the type's development in 2001, switched the order to the 777-200ER. The Northrop Grumman E-10 MC2A was to be a 767-400ER-based replacement for the USAF's 707-based E-3 Sentry AWACS, Northrop Grumman E-8 Joint STARS, and RC-135 SIGINT aircraft. The E-10 MC2A would have included an all-new AWACS system, with a powerful active electronically scanned array (AESA) that was also capable of jamming enemy aircraft or missiles. One 767-400ER aircraft was produced as a testbed for systems integration, but the program was terminated in January 2009 and the prototype was sold to Bahrain


title: "Boeing 767" content: as a VIP transport. In July 2018, 742 aircraft were in airline service: 73 -200s, 632 -300 and 37 -400 with 65 -300F on order; the largest operators are Delta Air Lines (77), FedEx (60; largest cargo operator), UPS Airlines (59), United Airlines (51), Japan Airlines (35), All Nippon Airways (34). The type's competitors included the Airbus A300 and A310. The largest customers are Delta Air Lines with 117 orders, FedEx Express (119), All Nippon Airways (96), American Airlines (88) and United Airlines (82). Delta and United are the only customers of all -200, -300 and -400 passenger variants. In


title: "Boeing 767" content: July 2015, FedEx placed a firm order for 50 Boeing 767 freighters with deliveries from 2018 to 2023. Boeing 767 orders and deliveries (cumulative, by year): , the Boeing 767 has been in 45 aviation occurrences, including 16 hull-loss accidents. Six fatal crashes, including three hijackings, have resulted in a total of 851 occupant fatalities. The 767's first incident was Air Canada Flight 143, a 767-200, on July 23, 1983. The airplane ran out of fuel in-flight and had to glide with both engines out for almost to an emergency landing at Gimli, Manitoba, Canada. The pilots used the aircraft's


title: "Boeing 767" content: ram air turbine to power the hydraulic systems for aerodynamic control. There were no fatalities and only minor injuries. This aircraft was nicknamed "Gimli Glider" after its landing site. The aircraft, registered C-GAUN, continued flying for Air Canada until its retirement in January 2008. The airliner's first fatal crash, Lauda Air Flight 004, occurred near Bangkok on May 26, 1991, following the in-flight deployment of the left engine thrust reverser on a 767-300ER; none of the 223 aboard survived; as a result of this accident all 767 thrust reversers were deactivated until a redesign was implemented. Investigators determined that an


title: "Boeing 767" content: electronically controlled valve, common to late-model Boeing aircraft, was to blame. A new locking device was installed on all affected jetliners, including 767s. On October 31, 1999, EgyptAir Flight 990, a 767-300ER, crashed off Nantucket Island, Massachusetts, in international waters killing all 217 people on board. The US National Transportation Safety Board (NTSB) concluded "not determined", but determined the probable cause to be due to a deliberate action by the first officer; Egypt disputed this conclusion. On April 15, 2002, Air China Flight 129, a 767-200ER, crashed into a hill amid inclement weather while trying to land at Gimhae International


title: "Boeing 767" content: Airport in Busan, South Korea. The crash resulted in the death of 129 of the 166 people on board, and the cause was attributed to pilot error. The 767 has been involved in six hijackings, three resulting in loss of life, for a combined total of 282 occupant fatalities. On November 23, 1996, Ethiopian Airlines Flight 961, a 767-200ER, was hijacked and crash-landed in the Indian Ocean near the Comoros Islands after running out of fuel, killing 125 out of the 175 persons on board; survivors have been rare among instances of land-based aircraft ditching on water. Two 767s were


title: "Boeing 767" content: involved in the September 11 attacks on the World Trade Center in 2001, resulting in the collapse of its two main towers. American Airlines Flight 11, a 767-200ER, crashed into the North Tower, killing all 92 people on board, and United Airlines Flight 175, a 767-200, crashed into the South Tower, with the death of all 65 on board. In addition, more than 2,600 people were killed in the towers or on the ground. A foiled 2001 shoe bomb plot involving an American Airlines 767-300ER resulted in passengers being required to remove their shoes for scanning at US security checkpoints.


title: "Boeing 767" content: On November 1, 2011, LOT Polish Airlines Flight 16, a 767-300ER, safely landed at Warsaw Frederic Chopin Airport in Warsaw, Poland after a mechanical failure of the landing gear forced an emergency landing with the landing gear up. There were no injuries, but the aircraft involved was damaged and subsequently written off. At the time of the incident, aviation analysts speculated that it may have been the first instance of a complete landing gear failure in the 767's service history. Subsequent investigation determined that while a damaged hose had disabled the aircraft's primary landing gear extension system, an otherwise functional


title: "Boeing 767" content: backup system was inoperative due to an accidentally deactivated circuit breaker. In January 2014, the US Federal Aviation Administration issued a directive that ordered inspections of the elevators on more than 400 767s beginning in March 2014; the focus is on fasteners and other parts that can fail and cause the elevators to jam. The issue was first identified in 2000 and has been the subject of several Boeing service bulletins. The inspections and repairs are required to be completed within six years. The aircraft has also had multiple occurrences of "uncommanded escape slide inflation" during maintenance or operations, and


title: "Boeing 767" content: during flight. In late 2015, the FAA issued a preliminary directive to address the issue. On October 28, 2016, American Airlines Flight 383, a 767-300ER with 161 passengers and 9 crew members, aborted takeoff at Chicago O'Hare Airport following an uncontained failure of the right GE CF6-80C2 engine. The engine failure, which hurled fragments over a considerable distance, caused a fuel leak resulting in a fire under the right wing. Fire and smoke entered the cabin. All passengers and crew evacuated the aircraft, with 20 passengers and one flight attendant sustaining minor injuries using the evacuation slides. As new 767s


title: "Boeing 767" content: roll off the assembly line, older models have been retired and stored or scrapped. One complete aircraft, N102DAthe first 767-200 to operate for Delta Air Lines and the twelfth example built, is currently on display. It was withdrawn from use and stored at Hartsfield–Jackson Atlanta International Airport in 2006. The exhibition aircraft, named "The Spirit of Delta" by the employees who helped purchase it in 1982, underwent restoration at the Delta Flight Museum in Atlanta, Georgia. The restoration was completed in 2010. Boeing 767 The Boeing 767 is a mid- to large-size, mid- to long-range, wide-body twin-engine jet airliner built


title: "Books of Samuel" content: are) a single book, but the first Greek translation, called Septuagint and produced around the second century BC, divided it into two; this was adopted by the Latin translations used in the early Christian church of the West, and finally introduced into Jewish bibles around the early 16th century. The Hebrew text, that is used by Jews today, called the Masoretic text, differs considerably from the Hebrew text that was the basis of the first Greek translation, and scholars are still working at finding the best solutions to the many problems this presents. According to passages 14b and 15a of


title: Bioterrorism content: and relatively easy to disperse”. Furthermore, Safir thought that efficiency in bioterrorism preparedness is not necessarily a question of money, but is instead dependent on putting resources in the right places. The broadcast suggested that the nation was not ready for something more serious. In a September 2016 interview conducted by Homeland Preparedness News, Daniel Gerstein, a senior policy researcher for the RAND Corporation, stresses the importance in preparing for potential bioterrorist attacks on the nation. He implored the U.S. government to take the proper and necessary actions to implement a strategic plan of action to save as many lives


title: Beaver content: Beaver The beaver (genus Castor) is a large, primarily nocturnal, semiaquatic rodent. "Castor" includes two extant species, the North American beaver ("Castor canadensis") (native to North America) and Eurasian beaver ("Castor fiber") (Eurasia). Beavers are known for building dams, canals, and lodges (homes). They are the second-largest rodent in the world (after the capybara). Their colonies create one or more dams to provide still, deep water to protect against predators, and to float food and building material. The North American beaver population was once more than 60 million, but as of 1988 was 6–12 million. This population decline is the


title: Beaver content: result of extensive hunting for fur, for glands used as medicine and perfume, and because the beavers' harvesting of trees and flooding of waterways may interfere with other land uses. Beavers, along with pocket gophers and kangaroo rats, are castorimorph rodents, a suborder of rodents mostly restricted to North America. Although just two closely related species exist today, beavers have a long fossil history in the Northern Hemisphere beginning in the Eocene, and many species of giant beaver existed until quite recently, such as "Trogontherium" in Europe, and "Castoroides" in North America. Beavers are known for their natural trait of


title: Beaver content: building dams on rivers and streams, and building their homes (known as "lodges") in the resulting pond. Beavers also build canals to float building materials that are difficult to haul over land. They use powerful front teeth to cut trees and other plants that they use both for building and for food. In the absence of existing ponds, beavers must construct dams before building their lodges. First they place vertical poles, then fill between the poles with a crisscross of horizontally placed branches. They fill in the gaps between the branches with a combination of weeds and mud until the


title: Beaver content: dam impounds sufficient water to surround the lodge. They are known for their alarm signal: when startled or frightened, a swimming beaver will rapidly dive while forcefully slapping the water with its broad tail, audible over great distances above and below water. This serves as a warning to beavers in the area. Once a beaver has sounded the alarm, nearby beavers will dive and may not reemerge for some time. Beavers are slow on land, but are good swimmers, and can stay under water for as long as 15 minutes. Beavers do not hibernate, but store sticks and logs in


title: Beaver content: a pile in their ponds, eating the underbark. Some of the pile is generally above water and accumulates snow in the winter. This insulation of snow often keeps the water from freezing in and around the food pile, providing a location where beavers can breathe when outside their lodge. Beavers have webbed hind-feet, and a broad, scaly tail. They have poor eyesight, but keen senses of hearing, smell, and touch. A beaver's teeth grow continuously so that they will not be worn down by chewing on wood. Their four incisors are composed of hard orange enamel on the front and


title: Beaver content: a softer dentin on the back. The chisel-like ends of incisors are maintained by their self-sharpening wear pattern. The enamel in a beaver's incisors contains iron and is more resistant to acid than enamel in the teeth of other mammals. Beavers continue to grow throughout their lives. Adult specimens weighing over are not uncommon. Females are as large as or larger than males of the same age, which is uncommon among mammals. Beavers live up to 24 years of age in the wild. The English word "beaver" comes from the Old English word "beofor" or "befer" (recorded earlier as "bebr"),


title: Beaver content: which in turn sprang from the Proto-Germanic root "*bebruz". Cognates in other Germanic languages include the Old Saxon "bibar", the Old Norse "bjorr", the Middle Dutch and Dutch "bever", the Low German "bever", the Old High German "bibar" and the Modern German "Biber". The Proto-Germanic word in turn came from the Proto-Indo-European (PIE) word "*bhebhrus", a reduplication of the PIE root "*bher-", meaning "brown" or "bright", whose own descendants now include the Lithuanian "bebras" and the Czech "bobr", as well as the Germanic forms. The North American and Eurasian beavers are the only extant members of the family Castoridae, contained


title: Beaver content: in a single genus, Castor. Genetic research has shown the modern European and North American beaver populations to be distinct species and that hybridization is unlikely. Although superficially similar to each other, there are several important differences between the two species. Eurasian beavers tend to be slightly larger, with larger, less rounded heads, longer, narrower muzzles, thinner, shorter and lighter underfur, narrower, less oval-shaped tails and shorter shin bones, making them less capable of bipedal locomotion than the North American species. Eurasian beavers have longer nasal bones than their North American cousins, with the widest point being at the end


title: Beaver content: of the snout for the former, and in the middle for the latter. The nasal opening for the Eurasian species is triangular, unlike that of the North American race, which is square. The "foramen magnum" is rounded in the Eurasian beaver and triangular in the North American. The anal glands of the Eurasian beaver are larger and thin-walled with a large internal volume compared to that of the North American species. The guard hairs of the Eurasian beaver have a longer hollow medulla at their tips. Fur colour is also different. Overall, 66% of Eurasian beavers have pale brown or


title: Beaver content: beige fur, 20% have reddish brown, nearly 8% are brown and only 4% have blackish coats. In North American beavers, 50% have pale brown fur, 25% are reddish brown, 20% are brown and 6% are blackish. The two species are not genetically compatible. North American beavers have 40 chromosomes, while Eurasian beavers have 48. More than 27 attempts were made in Russia to hybridize the two species, with one breeding between a male North American beaver and a female European resulting in a single stillborn kit. These factors make interspecific breeding unlikely in areas where the two species' ranges overlap.


title: Beaver content: The Eurasian beaver ("Castor fiber") was nearly hunted to extinction in Europe, both for fur and for "castoreum", a secretion from its scent gland believed to have medicinal properties. However, the beaver is now being re-introduced throughout Europe. Several thousand live on the Elbe and the Rhône and in parts of Scandinavia. A thriving community lives in northeast Poland, and the Eurasian beaver also returned to the Morava River banks in Slovakia and the Czech Republic. They have been reintroduced in Scotland (Knapdale), Bavaria, Austria, Netherlands, Serbia (Zasavica bog), Denmark (West Jutland) and Bulgaria and are spreading to new locations.


title: Beaver content: The beaver became extinct in Great Britain in the sixteenth century: Giraldus Cambrensis reported in 1188 ("Itinerarium" ii.iii) that it was to be found only in the Teifi in Wales and in one river in Scotland, though his observations are clearly second hand. In 2001, Kent Wildlife Trust successfully introduced a family of beavers at Ham Fen, the last remaining ancient fenland in the county close to the town of Sandwich; these are now established and are breeding. In October 2005, six Eurasian beavers were reintroduced to Britain in Lower Mill Estate in Gloucestershire; in July 2007 a colony of


title: Beaver content: four Eurasian beavers was established at Martin Mere in Lancashire, and a small population of probably Eurasian beavers is being monitored in Devon. A trial re-introduction occurred in Scotland in May 2009. Feasibility studies for a reintroduction to Wales are at an advanced stage and a preliminary study for a reintroduction of beavers to the wild in England has recently been published. The North American beaver ("Castor canadensis"), also called the Canadian beaver (which is also the name of a subspecies), American beaver, or simply beaver in North America, is native to Canada, much of the United States and the


title: Beaver content: states of Sonora and Chihuahua in northern Mexico. This species was introduced to the Argentine and Chilean Tierra del Fuego, as well as Finland, France, Poland and Russia. The North American beavers prefer the (inner) bark of aspen and poplar but will also take birch, maple, willow, alder, black cherry, red oak, beech, ash, hornbeam and occasionally pine and spruce. They will also eat cattails, water lilies and other aquatic vegetation, especially in the early spring (and contrary to widespread belief, they do not eat fish). These animals are often trapped for their fur. During the early 19th century, trapping


title: Beaver content: eliminated this animal from large portions of its original range. Beaver furs were used to make clothing and top-hats. Much of the early exploration of North America was driven by the quest for this animal's fur. Native peoples and early settlers also ate this animal's meat. The Federal Lacey Act was passed by the US Fish and Wildlife Service in 1900 which forebode any take of wildlife or plants in violation of Indian, State or foreign law. Through trap and transfer and habitat conservation, beavers made a nearly complete recovery by the 1940s.The current beaver population has been estimated to


title: Beaver content: be 10 to 15 million; one estimate claims that there may at one time have been as many as 90 million. The habitat of the beaver is the riparian zone, inclusive of stream bed. The actions of beavers for hundreds of thousands of years in the Northern Hemisphere have kept these watery systems healthy and in good repair. The beaver works as a keystone species in an ecosystem by creating wetlands that are used by many other species. Next to humans, no other extant animal appears to do more to shape its landscape. Beavers potentially even affect climate change. Beavers


title: Beaver content: fell trees for several reasons. They fell large mature trees, usually in strategic locations, to form the basis of a dam, but European beavers tend to use small diameter (<10 cm) trees for this purpose. Beavers fell small trees, especially young second-growth trees, for food. Broadleaved trees re-grow as a coppice, providing easy-to-reach stems and leaves for food in subsequent years. Ponds created by beavers can also kill some tree species by drowning, but this creates standing dead wood, which is very important for a wide range of animals and plants. Beaver dams are created as a protection against predators,


title: Beaver content: such as coyotes, wolves and bears, and to provide easy access to food during winter. Beavers always work at night and are prolific builders, carrying mud and stones with their fore-paws and timber between their teeth. Because of this, destroying a beaver dam without removing the beavers is difficult, especially if the dam is downstream of an active lodge. Beavers can rebuild such primary dams overnight, though they may not defend secondary dams as vigorously. Beavers may create a series of dams along a river. The ponds created by well-maintained dams help isolate the beavers' homes, which are called "lodges".


title: Beaver content: These are created from severed branches and mud. The beavers cover their lodges late each autumn with fresh mud, which freezes when frosts arrive. The mud becomes almost as hard as stone, thereby preventing wolves and wolverines from penetrating the lodge. The lodge has underwater entrances, which makes entry nearly impossible for any other animal, although muskrats have been seen living inside beaver lodges with the beavers who made them. Only a small amount of the lodge is actually used as a living area. Beavers dig out their dens with underwater entrances after they finish building the dams and lodge


title: Beaver content: structures. There are typically two dens within the lodge, one for drying off after exiting the water and another, drier one, in which the family lives. Beaver lodges are constructed with the same materials as the dams, with little order or regularity of structure. They seldom house more than four adults and six or eight juveniles. Some larger lodges have one or more partitions, but these are only posts of the main building left by the builders to support the roof. Usually, the dens have no connection with each other except by water. When the ice breaks up in spring,


title: Beaver content: beavers usually leave their lodges and roam until just before autumn, when they return to their old lodges and gather their winter stock of wood. They seldom begin to repair the lodges until the frost sets in, and rarely finish the outer coating until the cold becomes severe. When they erect a new lodge, they fell the wood early in summer but seldom begin building until nearly the end of August. Beaver ponds, and the wetlands that succeed them, remove sediments and pollutants from waterways, including total suspended solids, total nitrogen, phosphates, carbon and silicates. The term "beaver fever" is


title: Beaver content: a misnomer coined by the American press in the 1970s, following findings that the parasite "Giardia lamblia", which causes Giardiasis, is carried by beavers. However, further research has shown that many animals and birds carry this parasite, and the major source of water contamination is by other humans. Norway has many beavers but has not historically had giardia, and New Zealand has giardia but no beaver. Recent concerns point to domestic animals as a significant vector of giardia, with young calves in dairy herds testing as high as 100% positive for giardia. In addition, fecal coliform and streptococci bacteria excreted


title: Beaver content: into streams by grazing cattle have been shown to be reduced by beaver ponds, where the bacteria are trapped in bottom sediments. Beavers were trapped to near extirpation and had not been seen in New York City since the early 1800s. After 200 years, a beaver has returned to New York City, making its home along the Bronx River. In Chicago, several beavers have returned and made a home near the Lincoln Park's North Pond. The "Lincoln Park beaver" has not been as well received by the Chicago Park District and the Lincoln Park Conservancy, which was concerned over damage


title: Beaver content: to trees in the area. In March 2009, they hired an exterminator to remove a beaver family using live traps, and accidentally killed the mother when she got caught in a snare and drowned. Outside San Francisco, in downtown Martinez, California, a male and female beaver arrived in Alhambra Creek in 2006. The Martinez beavers built a dam 30 feet wide and at one time 6 feet high, and chewed through half the willows and other creekside landscaping the city planted as part of its $9.7 million 1999 flood-improvement project. When the city council wanted to remove the beavers because


title: Beaver content: of fears of flooding, local residents organized to protect them, forming an organization called "Worth a Dam". In the 1940s, beavers were brought from northern Manitoba in Canada to the island of Tierra Del Fuego in southern Chile and Argentina, for commercial fur production. However, the project failed and the beavers, ten pairs, were released into the wild. Having no natural predators in their new environment, they quickly spread throughout the island, and to other islands in the region, reaching a number of 100,000 individuals within just 50 years. They are now considered a serious invasive species in the region,


title: Beaver content: due to their massive destruction of forest trees, and efforts are being made for their eradication. The drastically different ecosystem has led to substantial environmental damage, as the ponds created by the beavers have no ecological purpose (wetlands do not form there as they do in the beavers' native territory) and there are no native, large predators. They have also been found to cross salt water to islands northward; a possible encroachment on the mainland has naturalists highly concerned. In contrast, areas with introduced beaver were associated with increased populations of native puye fish ("Galaxias maculatus"), whereas the exotic brook


title: Beaver content: trout ("Salvelinus fontinalis") and rainbow trout ("Oncorhynchus mykiss") had negative effects on native stream fishes in the Cape Horn Biosphere Reserve, Chile. Beavers are classed as a "prohibited new organism" under New Zealand's Hazardous Substances and New Organisms Act 1996, preventing them from legally being imported into the country. The basic units of beaver social organization are families consisting of an adult male and adult female in a monogamous pair and their kits and yearlings. Beaver families can have as many as ten members in addition to the monogamous pair. Groups this size or close to this size build more


title: Beaver content: lodges to live in while smaller families usually need only one. However, large families in the Northern Hemisphere have been recorded living in one lodge. Beaver pairs mate for life; however, if a beaver's mate dies, it will partner with another one. Extra-pair copulations also occur. In addition to being monogamous, both the male and female take part in raising offspring. They also both mark and defend the territory and build and repair the dam and lodge. When young are born, they spend their first month in the lodge and their mother is the primary caretaker while their father maintains


title: Beaver content: the territory. In the time after they leave the lodge for the first time, yearlings will help their parents build food caches in the fall and repair dams and lodges. Still, adults do the majority of the work and young beavers help their parents for reasons based on natural selection rather than kin selection. They are dependent on them for food and for learning life skills. Young beavers spend most of their time playing but also copy their parents' behavior. However, while copying behavior helps imprint life skills in young beavers, it is not necessarily immediately beneficial for parents as


title: Beaver content: the young beaver do not perform the tasks as well as the parents. Older offspring, which are around two years old, may also live in families and help their parents. In addition to helping build food caches and repairing the dam, two-year-olds will also help in feeding, grooming and guarding younger offspring. Beavers also practice alloparental care, in which an older sibling may take over the parenting duties if the original parents die or are otherwise separated from them. This behavior is common and is seen in many other animal species, such as the elephant and fathead minnow. While these


title: Beaver content: helping two-year-olds help increase the chance of survival for younger offspring, they are not essential for the family, and two-year-olds only stay and help their families if there is a shortage of resources in times of food shortage, high population density, or drought. When beavers leave their natal territories, they usually do not settle far. Beavers can recognize their kin by detecting differences in anal gland secretion composition using their keen sense of smell. Related beavers share more features in their anal gland secretion profile than unrelated beavers. Being able to recognize kin is important for beaver social behavior, and


title: Beaver content: it causes more tolerant behavior among neighboring beavers. Beavers maintain and defend territories, which are areas for feeding, nesting and mating. They invest much energy in their territories, building their dams and becoming familiar with the area. Beavers mark their territories by constructing scent mounts made of mud, debris and castoreum, a urine based substance excreted through the beavers castor sacs between the pelvis and base of the tail. These scent mounts are established on the border of the territory. Once a beaver detects another scent in its territory, finding the intruder takes priority, even over food. Because they invest


title: Beaver content: so much energy in their territories, beavers are intolerant of intruders and the holder of the territory is more likely to escalate an aggressive encounter. These encounters are often violent. To avoid such situations, a beaver marks its territory with as many scent mounds as possible, signaling to intruders that the territory holder has enough energy to maintain its territory and is thus able to put up a good defense. As such, territories with more scent mounts are avoided more often than ones with fewer mounts. Scent marking increases in August during the dispersal of yearlings, in an attempt to


title: Beaver content: prevent them from intruding on territories. Beavers also exhibit a behavior known as the "dear enemy effect". A territory-holding beaver will investigate and become familiar with the scents of its neighbors. As such they respond less aggressively to intrusions by their territorial neighbours than those made by non-territorial floaters or "strangers". Occurrences of beaver aggression, however, have been reported. In April 2013, an angler, near Minkovichi in the Brest region of Belarus, died after being bitten twice on the leg by a wild Eurasian beaver. Both beaver testicles and castoreum, a bitter-tasting secretion with a slightly fetid odor contained in


title: Beaver content: the castor sacs of male or female beaver, have been articles of trade for use in traditional medicine. Yupik medicine used dried beaver testicles like willow bark to relieve pain. Dried beaver testicles were also used as contraception. Beaver testicles were used as medicine in Iraq and Iran during the tenth to nineteenth century. Aesop's "Fables" describes beavers chewing off their testicles to preserve themselves from hunters, which is not possible because the beaver's testicles are inside its body. This belief, also recorded by Pliny the Elder, persisted in medieval bestiaries. European beavers ("Castor fiber") were eventually hunted nearly to


title: Beaver content: extinction in part for the production of castoreum, which was used as an analgesic, anti-inflammatory, and antipyretic. Castoreum was described in the 1911 British Pharmaceutical Codex for use in dysmenorrhea and hysterical conditions (i.e. pertaining to the womb), for raising blood pressure and increasing cardiac output. The activity of castoreum has been credited to the accumulation of salicin from willow trees in the beaver's diet, which is transformed to salicylic acid and has an action very similar to aspirin. Castoreum continues to be used in perfume production. Castoreum can be used as an enhancer of vanilla, strawberry and raspberry flavorings.


title: Beaver content: It is sometimes added to frozen dairy, gelatins, candy, and fruit beverages. Due to the difficulty and expense in obtaining castoreum, it is only very rarely used in common food products. Much of the early European exploration and trade of Canada was based on the quest for beaver. The most valuable part of the beaver is its inner fur whose many minute barbs make it excellent for felting, especially for hats. In Canada a "made beaver" or "castor gras" that a native had worn or slept on was more valuable than a fresh skin since this tended to wear off


title: Beaver content: the outer guard hairs. Beavers have been trapped for millennia, and this continues to this day. Beaver pelts were used for barter by Native Americans in the 17th century to gain European goods. They were then shipped back to Great Britain and France where they were made into clothing items. Widespread hunting and trapping of beavers led to their endangerment. Eventually, the fur trade declined due to decreasing demand in Europe and the takeover of trapping grounds to support the growing agriculture sector. A small resurgence in beaver trapping has occurred in some areas where there is an over-population of


title: Beaver content: beaver; trapping is done when the fur is of value, and the remainder of the animal may be used as feed. In the 1976/1977 season, 500,000 beaver pelts were harvested in North America. In wider culture, the beaver is famed for its industriousness and its building skills. The English verb "to beaver" means to work hard and constantly. "Beverly" or "Beverley", a placename found at various locations in the English-speaking world and also commonly used as a first name, derives from Old English, combining the words "befer" ("beaver") and "leah" ("clearing"). The show "Happy Tree Friends" features Toothy and Handy


title: Beaver content: who are beavers. The animated Nickelodeon show "The Angry Beavers" features Daggett and Norbert. The anthropomorphic Mr. and Mrs. Beaver have an important role in the plot of "The Lion, the Witch and the Wardrobe", first part of C.S.Lewis' "The Chronicles of Narnia". The first "Redwall" book features an unnamed beaver who helps Constance the badger build a bow, the only one ever seen before the books shifted to focus on animals commonly native to the English Isles. The 2014 American horror comedy film directed by Jordan Rubin called Zombeavers, which follows a group of college kids on a camping


title: Beaver content: trip that are attacked by a swarm of zombie beavers. The importance of the beaver in the development of Canada through the fur trade led to its official designation as the national animal in 1975. The animal has long been associated with Canada, appearing on the coat of arms of the Hudson's Bay Company in 1678. It is depicted on the Canadian five-cent piece and was on the first pictorial postage stamp issued in the Canadian colonies in 1849 (the so-called "Three-Penny Beaver"). As a national symbol, the beaver was chosen to be the mascot of the 1976 Summer Olympics


title: Beaver content: held in Montreal with the name "Amik" ("beaver" in Ojibwe). The beaver is also the symbol of many units and organizations within the Canadian Forces, such as on the cap badges of the Royal 22 Régiment, the Calgary Highlanders, the Royal Westminster Regiment and the Canadian Military Engineers. Toronto Police Services, London Police Service, Canadian Pacific Railway Police Service and Canadian Pacific Railway bear the beaver on their crest or coat of arms. Others who have used the beaver in their company or organizational symbol or as their mascot include: In the 17th century, based on a question raised by


title: Beaver content: the Bishop of Quebec, the Roman Catholic Church ruled that the beaver was a fish (beaver flesh was a part of the Yukoindigenous peoples' diet, prior to the Europeans' arrival) for purposes of dietary law. Therefore, the general prohibition on the consumption of meat on Fridays did not apply to beaver meat. The legal basis for the decision probably rests with the "Summa Theologica" of Thomas Aquinas, which bases animal classification as much on habit as anatomy. This is similar to the Church's classification of other semi-aquatic rodents, such as the capybara and muskrat. Beaver The beaver (genus Castor) is


title: Bear content: Bear Bears are carnivoran mammals of the family Ursidae. They are classified as caniforms, or doglike carnivorans. Although only eight species of bears are extant, they are widespread, appearing in a wide variety of habitats throughout the Northern Hemisphere and partially in the Southern Hemisphere. Bears are found on the continents of North America, South America, Europe, and Asia. Common characteristics of modern bears include large bodies with stocky legs, long snouts, small rounded ears, shaggy hair, plantigrade paws with five nonretractile claws, and short tails. While the polar bear is mostly carnivorous, and the giant panda feeds almost entirely


title: Bear content: on bamboo, the remaining six species are omnivorous with varied diets. With the exception of courting individuals and mothers with their young, bears are typically solitary animals. They may be diurnal or nocturnal and have an excellent sense of smell. Despite their heavy build and awkward gait, they are adept runners, climbers, and swimmers. Bears use shelters, such as caves and logs, as their dens; most species occupy their dens during the winter for a long period of hibernation, up to 100 days. Bears have been hunted since prehistoric times for their meat and fur; they have been used for


title: Bear content: bear-baiting and other forms of entertainment, such as being made to dance. With their powerful physical presence, they play a prominent role in the arts, mythology, and other cultural aspects of various human societies. In modern times, bears have come under pressure through encroachment on their habitats and illegal trade in bear parts, including the Asian bile bear market. The IUCN lists six bear species as vulnerable or endangered, and even least concern species, such as the brown bear, are at risk of extirpation in certain countries. The poaching and international trade of these most threatened populations are prohibited, but


title: Bear content: still ongoing. The English word "bear" comes from Old English ' and belongs to a family of names for the bear in Germanic languages, such as Swedish ', also used as a first name, that originate from an adjective meaning "brown". "Bear" therefore originally meant "the brown one." This terminology for the animal originated as a taboo avoidance term: proto-Germanic tribes replaced their original word for bear – "arkto" – with this euphemistic expression out of fear that speaking the animal's true name might cause it to appear. Bear taxon names such as Arctoidea and "Helarctos" come from the ancient


title: Bear content: Greek word ἄρκτος ("arktos"), meaning bear, as do the names "arctic" and "antarctic", from the constellation Ursa Major, the "Great Bear", prominent in the northern sky. Bear taxon names such as Ursidae and "Ursus" come from Latin "Ursus/Ursa", he-bear/she-bear. The female first name "Ursula", originally derived from a Christian saint's name, means "little she-bear" (diminutive of Latin "ursa"). In Switzerland, the male first name "Urs" is especially popular, while the name of the canton and city of Bern is derived from "Bär", German for bear. The Germanic name Bernard (including Bernhardt and similar forms) means "bear-brave", "bear-hardy", or "bold bear".


title: Bear content: The Old English name Beowulf is a kenning, "bee-wolf", for bear, in turn meaning a brave warrior. The family Ursidae is one of nine families in the suborder Caniformia, or "doglike" carnivorans, within the order Carnivora. Bears' closest living relatives are the pinnipeds, canids, and musteloids. Modern bears comprise eight species in three subfamilies: Ailuropodinae (monotypic with the giant panda), Tremarctinae (monotypic with the spectacled bear), and Ursinae (containing six species divided into one to three genera, depending on the authority). Nuclear chromosome analysis show that the karyotype of the six ursine bears is nearly identical, with each having 74


title: Bear content: chromosomes, whereas the giant panda has 42 chromosomes and the spectacled bear 52. These smaller numbers can be explained by the fusing of some chromosomes, and the banding patterns on these match those of the ursine species, but differ from those of procyonids, which supports the inclusion of these two species in Ursidae rather than in Procyonidae, where they had been placed by some earlier authorities. The earliest members of Ursidae belong to the extinct subfamily Amphicynodontinae, including "Parictis" (late Eocene to early middle Miocene, 38–18 Mya) and the slightly younger "Allocyon" (early Oligocene, 34–30 Mya), both from North America.


title: Bear content: These animals looked very different from today's bears, being small and raccoon-like in overall appearance, with diets perhaps more similar to that of a badger. "Parictis" does not appear in Eurasia and Africa until the Miocene. It is unclear whether late-Eocene ursids were also present in Eurasia, although faunal exchange across the Bering land bridge may have been possible during a major sea level low stand as early as the late Eocene (about 37 Mya) and continuing into the early Oligocene. European genera morphologically very similar to "Allocyon", and to the much younger American "Kolponomos" (about 18 Mya), are known


title: Bear content: from the Oligocene, including "Amphicticeps" and "Amphicynodon". There has been various morphological evidence linking amphicynodontines with pinnipeds, as both groups were semi-aquatic, otter-like mammals. In addition to the support of the pinniped–amphicynodontine clade, other morphological and some molecular evidence supports bears being the closet living relatives to pinnipeds. The raccoon-sized, dog-like "Cephalogale" is the oldest-known member of the subfamily Hemicyoninae, which first appeared during the middle Oligocene in Eurasia about 30 Mya. The subfamily includes the younger genera "Phoberocyon" (20–15 Mya), and "Plithocyon" (15–7 Mya). A "Cephalogale"-like species gave rise to the genus "Ursavus" during the early Oligocene (30–28 Mya);


title: Bear content: this genus proliferated into many species in Asia and is ancestral to all living bears. Species of "Ursavus" subsequently entered North America, together with "Amphicynodon" and "Cephalogale", during the early Miocene (21–18 Mya). Members of the living lineages of bears diverged from "Ursavus" between 15 and 20 Mya, likely via the species "Ursavus elmensis". Based on genetic and morphological data, the Ailuropodinae (pandas) were the first to diverge from other living bears about 19 Mya, although no fossils of this group have been found before about 5 Mya. The New World short-faced bears (Tremarctinae) differentiated from Ursinae following a dispersal


title: Bear content: event into North America during the mid-Miocene (about 13 Mya). They invaded South America (≈1 Ma) following formation of the Isthmus of Panama. Their earliest fossil representative is "Plionarctos" in North America (~ 10–2 Ma). This genus is probably the direct ancestor to the North American short-faced bears (genus "Arctodus"), the South American short-faced bears ("Arctotherium"), and the spectacled bears, "Tremarctos", represented by both an extinct North American species ("T. floridanus"), and the lone surviving representative of the Tremarctinae, the South American spectacled bear ("T. ornatus"). The subfamily Ursinae experienced a dramatic proliferation of taxa about 5.3–4.5 Mya, coincident with


title: Bear content: major environmental changes; the first members of the genus "Ursus" appeared around this time. The sloth bear is a modern survivor of one of the earliest lineages to diverge during this radiation event (5.3 Mya); it took on its peculiar morphology, related to its diet of termites and ants, no later than by the early Pleistocene. By 3–4 Mya, the species "Ursus minimus" appears in the fossil record of Europe; apart from its size, it was nearly identical to today's Asian black bear. It is likely ancestral to all bears within Ursinae, perhaps aside from the sloth bear. Two lineages


title: Bear content: evolved from "U. minimus": the black bears (including the sun bear, the Asian black bear, and the American black bear); and the brown bears (which includes the polar bear). Modern brown bears evolved from "U. minimus" via "Ursus etruscus", which itself is ancestral to the extinct Pleistocene cave bear. Species of Ursinae have migrated repeatedly into North America from Eurasia as early as 4 Mya during the early Pliocene. The polar bear is the most recently evolved species and descended from the brown bear around 400,000 years ago. The bears form a clade within the Carnivora. The red panda is


title: Bear content: not a bear but a musteloid. The cladogram is based on molecular phylogeny of six genes in Flynn, 2005. There are two phylogenetic hypotheses on the relationships among extant and fossil bear spcies. One is all species of bears are classified in seven subfamilies as adopted here and related articles: Amphicynodontinae, Hemicyoninae, Ursavinae, Agriotheriinae, Ailuropodinae, Tremarctinae, and Ursinae. Below is a cladogram of the subfamilies of bears after McLellan and Reiner (1992) and Qiu et a. (2014): The second alternative phylogenetic hypothesis was implemented by McKenna et al. (1997) is to classify all the bear species into the superfamily Ursoidea,


title: Bear content: with Hemicyoninae and Agriotheriinae being classified in the family "Hemicyonidae". Amphicynodontinae under this classification were classified as stem-pinnipeds in the superfamily Phocoidea. In the McKenna and Bell classification both bears and pinnipeds in a parvorder of carnivoran mammals known as Ursida, along with the extinct bear dogs of the family Amphicyonidae. Below is the cladogram based on McKenna and Bell (1997) classification: The phylogeny of extant bear species is shown in a cladogram based on complete mitochondrial DNA sequences from Yu et al., 2007. The giant panda, followed by the spectacled bear are clearly the oldest species. The relationships of


title: Bear content: the other species are not very well resolved, though the polar bear and the brown bear form a close grouping. The bear family includes the most massive extant terrestrial members of the order Carnivora. The polar bear is considered to be the largest extant species, with adult males weighing and measuring in total length. The smallest species is the sun bear, which ranges in weight and in length. Prehistoric North and South American short-faced bears were the largest species known to have lived. The latter estimated to have weighed and stood tall. Body weight varies throughout the year in bears


title: Bear content: of temperate and arctic climates, as they build up fat reserves in the summer and autumn and lose weight during the winter. Bears are generally bulky and robust animals with short tails. They are sexually dimorphic with regard to size, with males typically being larger. Larger species tend to show increased levels of sexual dimorphism in comparison to smaller species. Relying as they do on strength rather than speed, bears have relatively short limbs with thick bones to support their bulk. The shoulder blades and the pelvis are correspondingly massive. The limbs are much straighter than those of the big


title: Bear content: cats as there is no need for them to flex in the same way due to the differences in their gait. The strong forelimbs are used to catch prey, to excavate dens, to dig out burrowing animals, to turn over rocks and logs to locate prey, and to club large creatures. Unlike most other land carnivorans, bears are plantigrade. They distribute their weight toward the hind feet, which makes them look lumbering when they walk. They are capable of bursts of speed but soon tire, and as a result mostly rely on ambush rather than the chase. Bears can stand


title: Bear content: on their hind feet and sit up straight with remarkable balance. Their front paws are flexible enough to grasp fruit and leaves. Bears' non-retractable claws are used for digging, climbing, tearing, and catching prey. The claws on the front feet are larger than those on the back and may be a hindrance when climbing trees; black bears are the most arboreal of the bears, and have the shortest claws. Pandas are unique in having a bony extension on the wrist of the front feet which acts as a thumb, and is used for gripping bamboo shoots as the animals feed.


title: Bear content: Most mammals have agouti hair, with each individual hair shaft having bands of colour corresponding to two different types of melanin pigment. Bears however have a single type of melanin and the hairs have a single colour throughout their length, apart from the tip which is sometimes a different shade. The coat consists of long guard hairs, which form a protective shaggy covering, and short dense hairs which form an insulating layer trapping air close to the skin. The shaggy coat helps maintain body heat during winter hibernation and is shed in the spring leaving a shorter summer coat. Polar


title: Bear content: bears have hollow, translucent guard hairs which gain heat from the sun and conduct it to the dark-coloured skin below. They have a thick layer of blubber for extra insulation, and the soles of their feet have a dense pad of fur. Other than the bold black-and-white pelage of the panda, bears tend to be uniform in colour, although some species may have markings on the chest or face. Bears have small rounded ears so as to minimise heat loss, but neither their hearing or sight are particularly acute. Unlike many other carnivorans they have colour vision, perhaps to help


title: Bear content: them distinguish ripe nuts and fruits. They are unique among carnivorans in not having touch-sensitive whiskers on the muzzle; however, they have an excellent sense of smell, better than that of the dog, or possibly any other mammal. They use smell for signalling to each other (either to warn off rivals or detect mates) and for finding food. Smell is the principal sense used by bears to locate most of their food, and they have excellent memories which helps them to relocate places where they have found food before. The skulls of bears are massive, providing anchorage for the powerful


title: Bear content: masseter and temporal jaw muscles. The canine teeth are large but mostly used for display, and the molar teeth flat and crushing. Unlike most other members of the Carnivora, bears have relatively undeveloped carnassial teeth, and their teeth are adapted for a diet that includes a significant amount of vegetable matter. Considerable variation occurs in dental formula even within a given species. This may indicate bears are still in the process of evolving from a mainly meat-eating diet to a predominantly herbivorous one. Polar bears appear to have secondarily re-evolved carnassial-like cheek teeth, as their diets have switched back towards


title: Bear content: carnivory. Sloth bears lack lower central incisors and use their protusible lips for sucking up the termites on which they feed. The general dental formula for living bears is: . The structure of the larynx of bears appears to be the most basal of the caniforms. They possess air pouches connected to the pharynx which may amplify their vocalisations. Bears have a fairly simple digestive system typical for carnivorans, with a single stomach, short undifferentiated intestines and no cecum. Even the herbivorous giant panda still has the digestive system of a carnivore, as well as carnivore-specific genes. Its ability to


title: Bear content: digest cellulose is ascribed to the microbes in its gut. Bears must spend much of their time feeding in order to gain enough nutrition from foliage. The panda, in particular, spends 12–15 hours a day feeding. Extant bears are found in sixty countries primarily in the Northern Hemisphere and are concentrated in Asia, North America, and Europe. An exception is the spectacled bear; native to South America, it inhabits the Andean region. The sun bear's range extends below the equator in Southeast Asia. The Atlas bear, a subspecies of the brown bear was distributed in North Africa from Morocco to


title: Bear content: Libya, but it became extinct around the 1870s. The most widespread species is the brown bear, which occurs from Western Europe eastwards through Asia to the western areas of North America. The American black bear is restricted to North America, and the polar bear is restricted to the Arctic Sea. All the remaining species of bear are Asian. They occur in a range of habitats which include tropical lowland rainforest, both coniferous and broadleaf forests, prairies, steppes, montane grassland, alpine scree slopes, Arctic tundra and in the case of the polar bear, ice floes. Bears may dig their dens in


title: Bear content: hillsides or use caves, hollow logs and dense vegetation for shelter. Brown and American black bears are generally diurnal, meaning that they are active for the most part during the day, though they may forage substantially by night. Other species may be nocturnal, active at night, though female sloth bears with cubs may feed more at daytime to avoid competition from conspecifics and nocturnal predators. Bears are overwhelmingly solitary and are considered to be the most asocial of all the Carnivora. The only times bears are encountered in small groups are mothers with young or occasional seasonal bounties of rich


title: Bear content: food (such as salmon runs). Fights between males can occur and older individuals may have extensive scarring, which suggests that maintaining dominance can be intense. With their acute sense of smell, bears can locate carcasses from several kilometres away. They use olfaction to locate other foods, encounter mates, avoid rivals and recognise their cubs. Most bears are opportunistic omnivores and consume more plant than animal matter. They eat anything from leaves, roots, and berries to insects, carrion, fresh meat, and fish, and have digestive systems and teeth adapted to such a diet. At the extremes are the almost entirely herbivorous


title: Bear content: giant panda and the mostly carnivorous polar bear. However, all bears feed on any food source that becomes seasonally available. For example, Asiatic black bears in Taiwan consume large numbers of acorns when these are most common, and switch to ungulates at other times of the year. When foraging for plants, bears choose to eat them at the stage when they are at their most nutritious and digestible, typically avoiding older grasses, sedges and leaves. Hence, in more northern temperate areas, browsing and grazing is more common early in spring and later becomes more restricted. Knowing when plants are ripe


title: Bear content: for eating is a learned behaviour. Berries may be foraged in bushes or at the tops of trees, and bears try to maximize the number of berries consumed versus foliage. In autumn, some bear species forage large amounts of naturally fermented fruits, which affects their behaviour. Smaller bears climb trees to obtain mast (edible reproductive parts, such as acorns). Such masts can be very important to the diets of these species, and mast failures may result in long-range movements by bears looking for alternative food sources. Brown bears, with their powerful digging abilities, commonly eat roots. The panda's diet is


title: Bear content: over 99% bamboo, of 30 different species. Its strong jaws are adapted for crushing the tough stems of these plants, though they prefer to eat the more nutritious leaves. Bromeliads can make up to 50% of the diet of the spectacled bear, which also has strong jaws to bite them open. The sloth bear, though not as specialised as polar bears and the panda, has lost several front teeth usually seen in bears, and developed a long, suctioning tongue to feed on the ants, termites, and other burrowing insects they favour. At certain times of the year, these insects can


title: Bear content: make up 90% of their diets. Some species may raid the nests of wasps and bees for the honey and immature insects, in spite of stinging from the adults. Sun bears use their long tongues to lick up both insects and honey. Fish are an important source of food for some species, and brown bears in particular gather in large numbers at salmon runs. Typically, a bear plunges into the water and seizes a fish with its jaws or front paws. The preferred parts to eat are the brain and eggs. Small burrowing mammals like rodents may be dug out


title: Bear content: and eaten. The brown bear and both species of black bears sometimes take large ungulates, such as deer and bovids, mostly the young and weak. These animals may be taken by a short rush and ambush, though hiding young may be stiffed out and pounced on. The polar bear mainly preys on seals, stalking them from the ice or breaking into their dens. They primarily eat the highly digestible blubber. Large mammalian prey is typically killed by a bite to the head or neck, or (in the case of young) simply pinned down and mauled. Predatory behaviour in bears is


title: Bear content: typically taught to the young by the mother. Bears are prolific scavengers and kleptoparasites, stealing food caches from rodents, and carcasses from other predators. For hibernating species, weight gain is important as it provides nourishment during winter dormancy. A brown bear can eat of food and gain of fat a day prior to entering its den. Bears produce a number of vocal and non-vocal sounds. Tongue-clicking, grunting or chuffing many be made in cordial situations, such as between mothers and cubs or courting couples, while moaning, huffing, sorting or blowing air is made when an individual is stressed. Barking is


title: Bear content: produced during times of alarm, excitement or to give away the animal's position. Warning sounds include jaw-clicking and lip-popping, while teeth-chatters, bellows, growls, roars and pulsing sounds are made in aggressive encounters. Cubs may squeal, bawl, bleat or scream when in distress and make motor-like humming when comfortable or nursing. Bears sometimes communicate with visual displays such as standing upright, which exaggerates the individual's size. The chest markings of some species may add to this intimidating display. Staring is an aggressive act and the facial markings of spectacled bears and giant pandas may help draw attention to the eyes during


title: Bear content: agonistic encounters. Individuals may approach each other by stiff-legged walking with the head lowered. Dominance between bears is asserted by making a frontal orientation, showing the canine teeth, muzzle twisting and neck stretching. A subordinate may respond with a lateral orientation, by turning away and dropping the head and by sitting or lying down. Bears may mark territory by rubbing against trees and other objects which may serve to spread their scent. This is usually accompanied by clawing and biting the object. Bark may be spread around to draw attention to the marking post. Pandas are known to mark objects


title: Bear content: with urine and a waxy substance from their anal glands. Polar bears leave behind their scent in their tracks which allow individuals to keep track of one another in the vast Arctic wilderness. The mating system of bears has variously been described as a form of polygyny, promiscuity and serial monogamy. During the breeding season, males take notice of females in their vicinity and females become more tolerant of males. A male bear may visit a female continuously over a period of several days or weeks, depending on the species, to test her reproductive state. During this time period, males