The least weasel is small enough to be preyed upon by a range of other predators. Least weasel remains have been found in the excrement of red foxes, sables, steppe and forest polecat, stoats, eagle owls and buzzards. The owls most efficient at capturing least weasels are barn, barred, and great horned owls. Other birds of prey threatening to the least weasel include broad-winged and rough-legged buzzards. Some snake species may prey on the least weasel, including the black rat snake and copperhead. Aside from its smaller size, the least weasel is more vulnerable to predation than the stoat because it lacks a black predator deflection mark on the tail.
In areas where the least weasel is sympatric with the stoat, the two species compete with each other for rodent prey. The weasel manages to avoid too much competition by living in more upland areas, feeding on smaller prey and being capable of entering smaller holes. It actively avoids encounters with stoats, though female weasels are less likely to stop foraging in the presence of stoats, perhaps because their smaller size allows them to quickly escape into holes.


The least weasel (Mustela nivalis), little weasel, common weasel, or simply weasel is the smallest member of the genus Mustela, family Mustelidae and order Carnivora. It is native to Eurasia, North America and North Africa, and has been introduced to New Zealand, Malta, Crete, the Azores, and São Tomé. It is classified as least concern by the IUCN, due to its wide distribution and large population throughout the Northern Hemisphere.
The least weasel varies greatly in size over its range. The body is slender and elongated, and the legs and tail are relatively short. The colour varies geographically, as does the pelage type and length of tail. The dorsal surface, flanks, limbs and tail of the animal are usually some shade of brown while the underparts are white. The line delineating the boundary between the two colours is usually straight. At high altitudes and in the northern part of its range, the coat becomes pure white in winter. Eighteen subspecies are recognised.
Small rodents form the largest part of the least weasel's diet, but it also kills and eats rabbits, other mammals, and occasionally birds, birds' eggs, fish and frogs. Males mark their territories with olfactory signals and have exclusive home ranges which may intersect with or include several female ranges. Least weasels use pre-existing holes to sleep, store food and raise their young. Breeding takes place in the spring and summer, and there is a single litter of about six kits which are reared exclusively by the female. Due to its small size and fierce nature, the least weasel plays an important part in the mythology and legend of various cultures.


The least weasel mates in April–July and there is a 34- to 37-day gestation period. In the Northern Hemisphere, the average litter size consists of 6 kits and these reach sexual maturity in 3 to 4 months. Males may mate during their first year of life, though this is usually unsuccessful. They are fecund in February–October, though the early stages of spermatogenesis do occur throughout the winter months. Anestrus in females lasts from September until February.
The female raises its kits without help from the male. They are 1.5 to 4.5 g (0.05 to 0.16 oz) in weight at birth. Newborn kits are born pink, naked, blind and deaf, but gain a white coat of downy fur at the age of 4 days. At 10 days, the margin between the dark upper parts and light under parts becomes visible. The milk teeth erupt at 2 to 3 weeks of age, at which point the young start to eat solid food, though lactation can last 12 weeks. The eyes and ears open at 3 to 4 weeks of age, and by 8 weeks, killing behaviour is developed. The family breaks up after 9 to 12 weeks. There is a single litter each year and least weasels can live for 7 or 8 years.


The painted comber occurs over rocky bottom and among beds of Posidonia at depths of 5 to 150 metres (16 to 492 ft). It normally spends the day sheltering in rocky caves and is normally either solitary or found in small groups. It emerges at dusk to hunt. It is a carnivorous species which is a territorial ambush hunter and has a diet made up of cephalopods, bivalves, crustaceans, fishes, and worms. It is often used to indicate sites occupied by octopuses as it waits at the entrance scavenging the octopus's discarded parts of shellfish. The spawning season runs from late spring to early summer with the eggs being laid under stones near the shore. It is a synchronous hermaphrodite, i.e. each individual has both male and female gonads and may be capable of self-fertilisation. They have a maximum life expectancy of 16 years.


The painted comber, like most fishes, is host to a variety of internal and external parasites and these include the copepods Lernanthropus scribae, Caligus scribae and Anchistrotos laqueus; an isopod Gnathia sp.; a monogenean Protolamellodiscus serranelli; and two species of digeneans Helicometra fasciata and Lecithochirium musculus.


The painted comber is landed by artisanal fisheries using hook and line and trawls. It is said to have palatable flesh and can be prepared using a variety of cooking methods.


The painted comber has a laterally compressed, elongate body with a pointed snout. The dorsal fin has 10 spines and 4-16 soft rays and the anal fin has 3 spines and 7-8 soft rays. The caudal fin is truncate. It has a very large mouth for its size, which has many sharp teeth, and is protractile. The overall colour may be grey, purplish or reddish with 5-7 dark brown bars on the flanks. The head is marked with many narrow, wavy blue lines and red blotches. The dorsal, anal and caudal fins are marked with red dots. There is a diffuse, purplish-blue blotch in the middle of the body. The pelvic and pectoral fins are normally uniform pale yellow. The maximum recorded fish measurement is 36 centimetres (14 in), although 25 centimetres (9.8 in) is more typical.


Chinook may spend one to eight years in the ocean (averaging from three to four years) before returning to their home rivers to spawn. The salmon undergo radical morphological changes as they prepare for the spawning event ahead. Salmon lose the silvery blue they had as ocean fish, and their color darkens, sometimes with a radical change in hue. Salmon are sexually dimorphic, and the male salmon develop canine-like teeth and their jaws develop a pronounced curve or hook, called a "kype". Studies have shown that larger and more dominant male salmon have a reproductive advantage as female Chinook are often more aggressive toward smaller males.
Chinook spawn in larger and deeper waters than other salmon species and can be found on the spawning redds (nests) from September to December. The female salmon may lay her eggs in four to five nesting pockets within a redd. After laying eggs, females guard the redd from four to 25 days before dying, while males seek additional mates. Chinook eggs hatch 90 to 150 days after deposition, depending upon water temperature. Egg deposits are timed to ensure the young salmon fry emerge during an appropriate season for survival and growth. Fry and parr (young fish) usually stay in fresh water 12 to 18 months before traveling downstream to estuaries, where they remain as smolts for several months. Some Chinooks return to the fresh water one or two years earlier than their counterparts and are referred to as "jack" salmon. "Jack" salmon are typically less than 24 inches (61 cm) long but are sexually mature.
Chinook salmon (male)
The Yukon River has the longest freshwater migration route of any salmon, over 3,000 km (1,900 mi) from its mouth in the Bering Sea to spawning grounds upstream of Whitehorse, Yukon. Since Chinook rely on fat reserves for energy upon entering fresh water, commercial fish caught here are highly prized for their unusually high levels of heart-healthy omega-3 fatty acids. However, the high cost of harvest and transport from this rural area limits its affordability. The highest in elevation Chinook migrate to spawn is in the Upper Salmon River and Middle Fork of the Salmon River in Idaho. These fish travel over 7,000 feet (2,100 m) in elevation, and over 900 miles (1,400 km), in their migration through eight dams and reservoirs on the Columbia and Lower Snake Rivers.
Chinook eat insects, amphipods, and other crustaceans while young, and primarily other fish when older. Young salmon feed in streambeds for a short period until they are strong enough to journey out into the ocean and acquire more food. Chinook juveniles divide into two types: ocean-type and stream-type. Ocean-type Chinook migrate to salt water in their first year. Stream-type salmon spend one full year in fresh water before migrating to the ocean. After a few years in the ocean, adult salmon, then large enough to escape most predators, return to their original streambeds to mate. Chinook can have extended lifespans, where some fish spend one to five years in the ocean, reaching age eight. More northerly populations tend to have longer lives.
Salmon need adequate spawning habitat. Clean, cool, oxygenated, sediment-free fresh water is essential for egg development. Chinook use larger sediment (gravel) sizes for spawning than other Pacific salmon. Riparian vegetation and woody debris help juvenile salmon by providing cover and maintaining low water temperatures.
Chinook also need healthy ocean habitats. Juvenile salmon grow in clean, productive estuarine environments and gain the energy for migration. Later, they change physiologically to live in salt water. They rely on eelgrass and seaweeds for camouflage (protection from predators), shelter, and foraging habitat as they make their way to the open ocean. Adult fish need a rich, open ocean habitat to acquire the strength needed to travel back upstream, escape predators, and reproduce before dying. In his book King of Fish, David Montgomery writes, "The reserves of fish at sea are important to restocking rivers disturbed by natural catastrophes." Thus, it is vitally important for the fish to be able to reach the oceans (without man-made obstructions such as dams), so they can grow into healthy adult fish to sustain the species.
The bodies of water for salmon habitat must be clean and oxygenated. One sign of high productivity and growth rate in the oceans is the level of algae. Increased algal levels lead to higher levels of carbon dioxide in the water, which transfers into living organisms, fostering underwater plants and small organisms, which salmon eat. Algae can filter high levels of toxins and pollutants. Thus, it is essential for algae and other water-filtering agents to not be destroyed in the oceans because they contribute to the well-being of the food chain.
With some populations endangered, precautions are necessary to prevent overfishing and habitat destruction, including appropriate management of hydroelectric and irrigation projects. If too few fish remain because of fishing and land management practices, salmon have more difficulty reproducing. When one of these factors is compromised, affected stock can decline. One Seattle Times article states, "Pacific salmon have disappeared from 40 percent of their historic range outside Alaska," and concludes it is imperative for people to realize the needs of salmon and to try not to contribute to destructive practices that harm salmon runs.
In the Pacific Northwest, the summer runs of especially large Chinook once common (before dams and overfishing led to declines) were known as June hogs.
A Chinook's birthplace and later evolution can be tracked by looking at its otolith (ear) bone. The bone can record the chemical composition of the water the fish had lived in just like a tree's growth rings provide hints on dry and wet years. The bone is built with the chemical signature of the environment that hosted the fish. Researchers were able to tell where different individuals of Chinook were born and lived in the first year of their lives. Testing was done by measuring the strontium in the bones. Strontium can accurately show researchers the exact location and time of a fish swimming in a river.


The Chinook salmon /ʃɪˈnʊk/ (Oncorhynchus tshawytscha) is the largest and most valuable species of Pacific salmon in North America, as well as the largest in the genus Oncorhynchus. Its common name is derived from the Chinookan peoples. Other vernacular names for the species include king salmon, Quinnat salmon, Tsumen, spring salmon, chrome hog, Blackmouth, and Tyee salmon. The scientific species name is based on the Russian common name chavycha (чавыча).
Chinook are anadromous fish native to the North Pacific Ocean and the river systems of western North America, ranging from California to Alaska, as well as Asian rivers ranging from northern Japan to the Palyavaam River in the Arctic northeast Siberia. They have been introduced to other parts of the world, including New Zealand, thriving in Lake Michigan Great Lakes of North America and Michigan's western rivers, and Patagonia. A large Chinook is a prized and sought-after catch for a sporting angler. The flesh of the salmon is also highly valued for its dietary nutritional content, which includes high levels of important omega-3 fatty acids. Some populations are endangered; however, many are healthy. The Chinook salmon has not been assessed for the IUCN Red List. According to NOAA the Chinook salmon population along the California coast is declining, from factors such as overfishing, loss of freshwater and estuarine habitat, hydropower development, poor ocean conditions, and hatchery practices.


The Chinook is blue-green, red, or purple on the back and top of the head, with silvery sides and white ventral surfaces. It has black spots on its tail and the upper half of its body. Although spots are seen on the tail in pink salmon, and silver on the tail in coho and chum salmon, Chinook are unique among the Pacific salmon in combining black spots and silver on the tail. Another distinctive feature is a black gum line that is present in both salt and freshwater. Adult fish range in size from 24 to 36 in (61 to 91 cm), but may be up to 58 in (150 cm) in length; they average 10 to 50 lb (4.5 to 22.7 kg), but may reach 130 lb (59 kg). The meat can be either pink or white in color, depending on what the salmon have been feeding on.
Chinook salmon are the largest of the Pacific salmon. In the Kenai River of Alaska, mature Chinook averaged 16.8 kg (37 lb). The current sport-caught world record, 97.25 lb (44.11 kg), was caught on May 17, 1985, in the Kenai River. The commercial catch world record is 126 lb (57 kg) caught near Rivers Inlet, British Columbia, in the late 1970s.


The nine-banded armadillo (Dasypus novemcinctus), also known as the nine-banded long-nosed armadillo or common long-nosed armadillo, is a mammal found in North, Central, and South America, making it the most widespread of the armadillos. Its ancestors originated in South America, and remained there until the formation of the Isthmus of Panama allowed them to enter North America as part of the Great American Interchange.
The nine-banded armadillo is a solitary, mainly nocturnal animal, found in many kinds of habitats, from mature and secondary rainforests to grassland and dry scrub. It is an insectivore, feeding chiefly on ants, termites, and other small invertebrates. The armadillo can jump 3–4 ft (91–122 cm) straight in the air if sufficiently frightened, making it a particular danger on roads. It is the state small mammal of Texas.


If alarmed, nine-banded armadillos can flee with surprising speed. Occasionally, a large predator may be able to ambush the armadillo before it can clear a distance, and breach the hard carapace with a well-placed bite or swipe. If the fleeing escape fails, the armadillo may quickly dig a shallow trench and lodge itself inside. Predators are rarely able to dislodge the animal once it has burrowed itself, and abandon their prey when they cannot breach the armadillo's armor or grasp its tapered tail. Due to their softer carapaces, juvenile armadillos are more likely to fall victim to natural predation and their cautious behavior generally reflects this. Young nine-banded armadillos tend to forage earlier in the day and are more wary of the approach of an unknown animal (including humans) than are adults. Their known natural predators include cougars (perhaps the leading predator), maned wolves, coyotes, black bears, red wolves, jaguars, alligators, bobcats, and large raptors. By far the leading predator of nine-banded armadillos today is humans, as armadillos are locally harvested for their meat and shells and many thousands fall victim to auto accidents every year.


Mating takes place during a two-to-three month long mating season, which occurs from July–August in the Northern Hemisphere and November–January in the Southern Hemisphere. A single egg is fertilized, but implantation is delayed for three to four months to ensure the young will not be born during an unfavorable time. Once the zygote does implant in the uterus, a gestation period of four months occurs, during which the zygote splits into four identical embryos, attached by a common placenta. They are born in March and weigh 3 oz (85 g). After birth, the quadruplets remain in the burrow, living off the mother's milk for about three months. They then begin to forage with the mother, eventually leaving after six months to a year.
Nine-banded armadillos reach sexual maturity at the age of one year, and reproduce every year for the rest of their 12–to-15 year lifespans. A single female can produce up to 56 young over the course of her life. This high reproductive rate is a major cause of the species’ rapid expansion.


The central stoneroller is widespread in freshwater streams throughout a large portion of the eastern, central, and midwestern United States. It is present in the Atlantic Ocean, Great Lakes, Mississippi River, and Hudson Bay basins in the US, from New York west to North Dakota and Wyoming and south to South Carolina and Texas.  Isolated populations are also found in Canada and Mexico.  The central stoneroller is benthopelagic, inhabiting either the midwaters or bottom of freshwater streams and rivers.   It requires some current and is most commonly found in riffles and pools of moderate to high gradient streams with a gravel substrate bottom.  However, it is a very tolerant species and can be found in almost any stream system with adequate food, leading to it widespread distribution.


The central stoneroller (Campostoma anomalum) is a fish in the family Cyprinidae endemic to North America.


The central stoneroller is generally herbivorous, feeding primarily on algae scraped from rocks and logs with the cartilaginous ridge on its lower jaw. Young fish feed on rotifers, filamentous algae, and microcrustacea. It also feeds on detritus, diatoms, and occasionally aquatic insects. It is classified as a grazing minnow in its feeding behavior, and large schools of these fish often feed together.  Central stonerollers may consume up to 27 percent of their body weight in benthic algae per day. One Kansas study found that algae contributed most (47 percent) to the diet of central stonerollers, followed by detritus (30 percent), animal matter (21 percent), and terrestrial vegetation (2 percent). Some human-induced factors that reduce the abundance of the central stoneroller are altered flow regimens, habitat fragmentation, impacts to aquatic and riparian habitat associated with agricultural practices, and increased siltation and aquatic vegetation.


Prior to the near extermination of wolves and cougars, the coyote was most numerous in grasslands inhabited by bison, pronghorn, elk, and other deer, doing particularly well in short-grass areas with prairie dogs, though it was just as much at home in semiarid areas with sagebrush and jackrabbits or in deserts inhabited by cactus, kangaroo rats, and rattlesnakes. As long as it was not in direct competition with the wolf, the coyote ranged from the Sonoran Desert to the alpine regions of adjoining mountains or the plains and mountainous areas of Alberta. With the extermination of the wolf, the coyote's range expanded to encompass broken forests from the tropics of Guatemala and the northern slope of Alaska.
Coyotes walk around 5–16 kilometres (3–10 mi) per day, often along trails such as logging roads and paths; they may use iced-over rivers as travel routes in winter. They are often crepuscular, being more active around evening and the beginning of the night than during the day. Like many canids, coyotes are competent swimmers, reported to be able to travel at least 0.8 kilometres (0.5 mi) across water.


The coyote (Canis latrans) is a species of canine native to North America. It is smaller than its close relative, the wolf, and slightly smaller than the closely related eastern wolf and red wolf. It fills much of the same ecological niche as the golden jackal does in Eurasia. The coyote is larger and more predatory and was once referred to as the American jackal by a behavioral ecologist. Other historical names for the species include the prairie wolf and the brush wolf.
The coyote is listed as least concern by the International Union for Conservation of Nature, due to its wide distribution and abundance throughout North America. The species is versatile, able to adapt to and expand into environments modified by humans. It is enlarging its range by moving into urban areas in the eastern U.S. and Canada. The coyote was sighted in eastern Panama (across the Panama Canal from their home range) for the first time in 2013.
The coyote has 19 recognized subspecies. The average male weighs 8 to 20 kg (18 to 44 lb) and the average female 7 to 18 kg (15 to 40 lb). Their fur color is predominantly light gray and red or fulvous interspersed with black and white, though it varies somewhat with geography. It is highly flexible in social organization, living either in a family unit or in loosely knit packs of unrelated individuals. Primarily carnivorous, its diet consists mainly of deer, rabbits, hares, rodents, birds, reptiles, amphibians, fish, and invertebrates, though it may also eat fruits and vegetables on occasion. Its characteristic vocalization is a howl made by solitary individuals. Humans are the coyote's greatest threat, followed by cougars and gray wolves. In spite of this, coyotes sometimes mate with gray, eastern, or red wolves, producing "coywolf" hybrids. In the northeastern regions of North America, the eastern coyote (a larger subspecies, though still smaller than wolves) is the result of various historical and recent matings with various types of wolves. Genetic studies show that most North American wolves contain some level of coyote DNA.
The coyote is a prominent character in Native American folklore, mainly in Aridoamerica, usually depicted as a trickster that alternately assumes the form of an actual coyote or a man. As with other trickster figures, the coyote uses deception and humor to rebel against social conventions. The animal was especially respected in Mesoamerican cosmology as a symbol of military might. After the European colonization of the Americas, it was seen in Anglo-American culture as a cowardly and untrustworthy animal. Unlike wolves, which have seen their public image improve, attitudes towards the coyote remain largely negative.


In areas where the ranges of coyotes and gray wolves overlap, interference competition and predation by wolves has been hypothesized to limit local coyote densities. Coyote ranges expanded during the 19th and 20th centuries following the extirpation of wolves, while coyotes were driven to extinction on Isle Royale after wolves colonized the island in the 1940s. One study conducted in Yellowstone National Park, where both species coexist, concluded that the coyote population in the Lamar River Valley declined by 39% following the reintroduction of wolves in the 1990s, while coyote populations in wolf inhabited areas of the Grand Teton National Park are 33% lower than in areas where they are absent. Wolves have been observed to not tolerate coyotes in their vicinity, though coyotes have been known to trail wolves to feed on their kills.
Coyotes may compete with cougars in some areas. In the eastern Sierra Nevada, coyotes compete with cougars over mule deer. Cougars normally outcompete and dominate coyotes, and may kill them occasionally, thus reducing coyote predation pressure on smaller carnivores such as foxes and bobcats. Coyotes that are killed are sometimes not eaten, perhaps indicating that these comprise competitive interspecies interactions, however there are multiple confirmed cases of cougars also eating coyotes. In northeastern Mexico, cougar predation on coyotes continues apace but coyotes were absent from the prey spectrum of sympatric jaguars, apparently due to differing habitat usages.
Other than by gray wolves and cougars, predation on adult coyotes is relatively rare but multiple other predators can be occasional threats. In some cases, adult coyotes have been preyed upon by both American black and grizzly bears, American alligators, large Canada lynx and golden eagles. At kill sites and carrion, coyotes, especially if working alone, tend to be dominated by wolves, cougars, bears, wolverines and, usually but not always, eagles (i.e., bald and golden). When such larger, more powerful and/or more aggressive predators such as these come to a shared feeding site, a coyote may either try to fight, wait until the other predator is done or occasionally share a kill, but if a major danger such as wolves or an adult cougar is present, the coyote will tend to flee.
Coyotes rarely kill healthy adult red foxes, and have been observed to feed or den alongside them, though they often kill foxes caught in traps. Coyotes may kill fox kits, but this is not a major source of mortality. In southern California, coyotes frequently kill gray foxes, and these smaller canids tend to avoid areas with high coyote densities.
In some areas, coyotes share their ranges with bobcats. These two similarly-sized species rarely physically confront one another, though bobcat populations tend to diminish in areas with high coyote densities. However, several studies have demonstrated interference competition between coyotes and bobcats, and in all cases coyotes dominated the interaction. Multiple researchers reported instances of coyotes killing bobcats, whereas bobcats killing coyotes is more rare. Coyotes attack bobcats using a bite-and-shake method similar to what is used on medium-sized prey. Coyotes (both single individuals and groups) have been known to occasionally kill bobcats – in most cases, the bobcats were relatively small specimens, such as adult females and juveniles. However, coyote attacks (by an unknown number of coyotes) on adult male bobcats have occurred. In California, coyote and bobcat populations are not negatively correlated across different habitat types, but predation by coyotes is an important source of mortality in bobcats. Biologist Stanley Paul Young noted that in his entire trapping career, he had never successfully saved a captured bobcat from being killed by coyotes, and wrote of two incidents wherein coyotes chased bobcats up trees. Coyotes have been documented to directly kill Canada lynx on occasion, and compete with them for prey, especially snowshoe hares. In some areas, including central Alberta, lynx are more abundant where coyotes are few, thus interactions with coyotes appears to influence lynx populations more than the availability of snowshoe hares.


Like the Eurasian golden jackal, the coyote is gregarious, but not as dependent on conspecifics as more social canid species like wolves are. This is likely because the coyote is not a specialized hunter of large prey as the latter species is. The basic social unit of a coyote pack is a family containing a reproductive female. However, unrelated coyotes may join forces for companionship, or to bring down prey too large to attack singly. Such "nonfamily" packs are only temporary, and may consist of bachelor males, nonreproductive females and subadult young. Families are formed in midwinter, when females enter estrus. Pair bonding can occur 2–3 months before actual copulation takes place. The copulatory tie can last 5–45 minutes. A female entering estrus attracts males by scent marking and howling with increasing frequency. A single female in heat can attract up to seven reproductive males, which can follow her for as long as a month. Although some squabbling may occur among the males, once the female has selected a mate and copulates, the rejected males do not intervene, and move on once they detect other estrous females. Unlike the wolf, which has been known to practice both monogamous and bigamous matings, the coyote is strictly monogamous, even in areas with high coyote densities and abundant food. Females that fail to mate sometimes assist their sisters or mothers in raising their pups, or join their siblings until the next time they can mate. The newly mated pair then establishes a territory and either constructs their own den or cleans out abandoned badger, marmot, or skunk earths. During the pregnancy, the male frequently hunts alone and brings back food for the female. The female may line the den with dried grass or with fur pulled from her belly. The gestation period is 63 days, with an average litter size of six, though the number fluctuates depending on coyote population density and the abundance of food.
Coyote pups are born in dens, hollow trees, or under ledges, and weigh 200 to 500 g (0.44 to 1.10 lb) at birth. They are altricial, and are completely dependent on milk for their first 10 days. The incisors erupt at about 12 days, the canines at 16, and the second premolars at 21. Their eyes open after 10 days, by which point the pups become increasingly more mobile, walking by 20 days, and running at the age of six weeks. The parents begin supplementing the pup's diet with regurgitated solid food after 12–15 days. By the age of four to six weeks, when their milk teeth are fully functional, the pups are given small food items such as mice, rabbits, or pieces of ungulate carcasses, with lactation steadily decreasing after two months. Unlike wolf pups, coyote pups begin seriously fighting (as opposed to play fighting) prior to engaging in play behavior. A common play behavior includes the coyote "hip-slam". By three weeks of age, coyote pups bite each other with less inhibition than wolf pups. By the age of four to five weeks, pups have established dominance hierarchies, and are by then more likely to play rather than fight. The male plays an active role in feeding, grooming, and guarding the pups, but abandons them if the female goes missing before the pups are completely weaned. The den is abandoned by June to July, and the pups follow their parents in patrolling their territory and hunting. Pups may leave their families in August, though can remain for much longer. The pups attain adult dimensions at eight months and gain adult weight a month later.


The sargo or white seabream (Diplodus sargus) is a species of seabream native to the eastern Atlantic and western Indian Oceans. It is found from the Bay of Biscay southwards to South Africa, including Madeira and the Canary Islands, the Mediterranean and (rarely) the Black Sea. Occasionally individuals are found off the Indian Ocean coasts of South Africa, Mozambique and Madagascar, and they are very rarely found elsewhere in the Indian Ocean, such as off Oman. An active fish, they inhabit the surf zone, but they may be found down to 50 m.
They consume small crustaceans, mollusks and some seaweed and coral, using their strong jaws to crush shells. Individuals can reach 45 cm, but average 22 cm.
Diplodus sargus are protandrous hermaphrodites, with individuals starting out life as males, and some becoming female later on.
It is commercially fished, with 3,713 t taken in 2008. Some are reared using aquacultural techniques. The catch is eaten immediately or marketed locally, as the flesh tastes good only when fresh.
Two US Navy submarines were named for this nimble fish, USS Sargo (SS-188) and USS Sargo (SSN-583).


The Eurasian otter is the most widely distributed otter species, its range including parts of Asia and Africa, as well as being spread across Europe, south to Palestine. Though currently thought to be extinct in Liechtenstein and Switzerland, it is now common in Latvia, along the coast of Norway, in the western regions of Spain and Portugal and across Great Britain and Ireland. In Italy, it lives in southern parts of the peninsula.
It inhabits unpolluted bodies of fresh water such as lakes, streams, rivers, canals and ponds, as long as the food supply is adequate. In Andalusia, it uses artificial lakes on golf courses. It prefers the open areas of the streams and also lives along the coast in salt water, but requires regular access to fresh water to clean its fur.
In Syria, the Eurasian otter was recorded in montane creeks in Latakia and Raqqa Governorates and in the lower Euphrates valley in Deir ez-Zor Governorate.
In western Nepal, its presence was documented at elevations of around 1,600 m (5,200 ft) in Barekot river in Jajarkot District and at 1,337 m (4,386 ft) in Tubang river in Eastern Rukum District.
In India, it is distributed in the Himalayan foothills, southern Western Ghats and the central Indian landscape.


The Eurasian otter's diet mainly consists of fish. Fish is its most preferred choice of food in Mediterranean and temperate freshwater habitats. During the winter and in colder environments, it also feeds on amphibians, crustaceans, insects, birds and sometimes small mammals, including young European beavers.
As with various other mustelid species, otters are capable of overpowering and killing prey significantly larger than themselves, and are known to hunt large waterbirds such as adult greylag geese on occasion.


The Eurasian otter (Lutra lutra), also known as the European otter, Eurasian river otter, common otter, and Old World otter, is a semiaquatic mammal native to Eurasia. The most widely distributed member of the otter subfamily (Lutrinae) of the weasel family (Mustelidae), it is found in the waterways and coasts of Europe, many parts of Asia, and parts of northern Africa. The Eurasian otter has a diet mainly of fish, and is strongly territorial. It is endangered in some parts of its range, but is recovering in others.


Eurasian otters are strongly territorial, living alone for the most part. An individual's territory may vary between about 1 and 40 km (1–25 mi) long, with about 18 km (11 mi) being usual. The length of the territory depends on the density of food available and the width of the water suitable for hunting (it is shorter on coasts, where the available width is much wider, and longer on narrower rivers). The Eurasian otter uses its feces, called spraints, to mark its territory and prioritize the use of resources to other group members. The territories are only held against members of the same sex, so those of males and females may overlap. Mating takes place in water. Eurasian otters are nonseasonal breeders (males and females will breed at any time of the year) and it has been found that their mating season is most likely determined simply by the otters' reproductive maturity and physiological state. Female otters become sexually mature between 18 and 24 months old and the average age of first breeding is found to be 2+1⁄2 years. Gestation for the Eurasian otter is 60–64 days, the litter weighing about 10% of the female body mass. After the gestation period, one to four pups are born, which remain dependent on the mother for about 13 months. The male plays no direct role in parental care, although the territory of a female with her pups is usually entirely within that of the male. Hunting mainly takes place at night, while the day is usually spent in the Eurasian otter's holt (den) – usually a burrow or hollow tree on the riverbank which can sometimes only be entered from underwater. Though long thought to hunt using sight and touch only, evidence is emerging that they may also be able to smell underwater – possibly in a similar manner to the star-nosed mole.


The southern cricket frog or southeastern cricket frog (Acris gryllus) is a small hylid frog native to the Southeastern United States. It is very similar in appearance and habits to the northern cricket frog, Acris crepitans, and was considered formerly conspecific (Dickerson 1906). The scientific name Acris is from the Greek word for locust, and the species name gryllus is Latin for cricket (Georgia Wildlife).


The southern cricket frog is characteristic of coastal plain bogs, bottomland swamps, ponds, and ditches. It prefers sunny areas, and is usually not found in woodlands. Subspecies Acris gryllus gryllus is found in the Atlantic Coastal Plain from southeastern Virginia through the Carolinas, Georgia, Alabama, and Mississippi, west to the Mississippi River. It is found mostly east of the Fall Line, but extends into more upland areas of the Piedmont along river valleys. Subspecies Acris gryllus dorsalis is found throughout the Florida peninsula.


At 0.75–1.5 inches (16–32 mm) in length, Acris gryllus is even smaller than A. crepitans. Other characters that differentiate the southern species are:
More pointed snout--A. crepitans more blunt.
Hind leg is more than half length of the body when folded—that of A. crepitans is less than one half body length. When rear leg is extended forward, the heel of A. gryllus usually reaches beyond the snout—does not reach snout in A. crepitans.
A. gryllus can jump longer distances than A. crepitans.
A. gryllus has a sharply-defined black stripe on the back of the thigh--A. crepitans has a ragged stripe.
Webbing on rear feet of A. gryllus is sparse, more extensive in A. crepitans.


Breeding is in late spring and summer. The advertisement call of the males is a loud rapid gick, gick, gick. Up to 150 eggs are laid at a time, and more than one mass may be produced in a season (Martof et al. 1980).


The Cape river frog (Amietia fuscigula) is a species of frog in the family Pyxicephalidae named for the Cape of Good Hope.  Formerly, it was placed in the family Ranidae.  It occurs widely in the Eastern Cape and Western Cape provinces of South Africa. A newly described species, A. poyntoni, was split from this species in 2013.


The Cape river frog occurs in a wide range of temperate to tropical habitats wherever fresh water is at least sufficient seasonally for breeding, including arable land, pastureland, savanna, shrubland, fynbos, grassland, rivers, swamps, freshwater lakes, marshes and springs, water storage areas, ponds, dams, and sewage treatment areas. Sometimes they even will occupy and breed in domestic water containers such as water butts or horse troughs.


The Cape river frog is a fairly large, typical frog with a snout-to-vent measurement of up to about 125 mm.  The snout is slightly rounded. It has a powerful, athletic build with long hind legs and feet, well adapted for leaping, but also well webbed; the species is a powerful swimmer. The fore feet are not webbed. When the animal sits at rest on a level surface, the tip of the longest rear toe reaches to directly below the tympanum.
The ventral skin is smooth and white, except for dark mottling on the throat. The mottling inspired the specific epithet fuscigula: Latin for "dusky throated".  In some specimens, the mottling extends to the belly. The dorsal skin bears a modest sprinkling of small, rounded protuberances and segments of longitudinal ridges. The colour scheme is variable, ranging from dark- through light-brown, also commonly green or olive, or with green streaks. The back and limbs are more or less conspicuously blotched with darker irregular spots.
Little sexual dimorphism is noted, but the male in breeding season bears a dark, swollen nuptial pad on each thumb.
The eye and tympanum are prominent; the diameter of the tympanum is barely smaller than that of the eye.


The European hedgehog is endemic to Europe (including European Russia), with a global distribution extending from the British Isles and the Iberian Peninsula eastwards through much of western to central Europe, and from southern Fennoscandia and the northern Baltic to north-west Russia. It is present also on Mediterranean islands (Corsica, Sardinia, Elba, Sicily), on most of the French Atlantic islands as well as on British Islands (autochthonous and introduced). It is an invasive exotic species in New Zealand and has probably been introduced to Ireland and many of the smaller islands where it occurs.
Colonists took hedgehogs from England and Scotland to New Zealand on sailing ships from the 1860s to the 1890s mainly as a biological control against agricultural pests or as a pet. Few survived the ca 50–100 days voyage, but those that did had lost all their fleas. Animals found their first homes in the South Island, where their spread was helped by guards dropping them off at country railway stations. Hedgehogs were introduced to the North Island in the 1890s, but some were also transported from South Island between 1906 and 1911 and, from then on, their numbers increased at an exponential rate. By the 1920s they had become so numerous that game-bird hunters blamed them for reduced bag-sizes. Hedgehogs were declared noxious animals and a bounty of one shilling a snout paid by regional authorities for several years. By the 1950s, hedgehogs could be found over the whole country with the exception of the coldest wettest corner of the South Island and alpine areas of permanent snow. Nevertheless, hedgehogs have been seen climbing New Zealand glaciers. Hedgehogs do not reach the same weight in New Zealand as in colder parts of Europe. With its milder winters, New Zealand hedgehogs hibernate for only three months of the year so do not need to put on so much weight in autumn as their ancestors.  In northern New Zealand, many hedgehogs do not hibernate at all. One of New Zealand's pioneer hedgehogs probably had faulty teeth for this feature is found in about 50% of today's animals. Most New Zealanders welcome hedgehogs in their gardens as they relish slugs and snails. Conservationists are less happy as hedgehogs compete for invertebrate food with native bush birds and prey on some rare insects, lizards and ground-nesting birds. As a result, extensive hedgehog-control programs are under way in some parts of the country, killing thousands of them. To judge by roadkill counts, North Island hedgehogs were at their highest numbers in the 1950s. Since then, roadkill counts have fallen dramatically from about 50/100 km to less than 1/100 km.
The European hedgehog is found across a wide range of habitat types, encompassing both semi-natural vegetation types and those areas that have been heavily modified by man. The range includes woodland, grasslands such as meadows and pasture, arable land, orchards and vineyards as well as within the matrix of habitat types found in human settlements. It prefers lowlands and hills up to 400–600m, but is also locally present on mountains, exceptionally up to an altitude of 1500-2000m (e.g. Alps and Pyrenees). Outside cultivated land it prefers marginal zones of forests, particularly ecotonal grass and scrub vegetation.
Hedgehogs are most abundant within the gardens, parks and amenity land close to or within human settlements. They are generally scarce in areas of coniferous woodland, marshes and moorland, probably because of a lack of suitable sites and materials for the construction of winter nests (or hibernacula), which have specific requirements.


The European hedgehog is an insectivore. Its diet consists largely of earthworms as well as snails and slugs, beetles, and caterpillars and other insect larvae. Eggs of ground-nesting birds are also taken, and carcasses may be foraged on. Plant matter appears to make up only a negligible part of the hedgehog's diet.


European hedgehogs may live to ten years of age, although the average life expectancy is three years. Starvation is the most common cause of death, usually occurring during hibernation. If alarmed, the animal will roll into a ball to protect itself. Many potential predators are repelled by its spines, but predation does occur. Remains of hedgehogs have been found in the stomachs of red foxes (Vulpes vulpes), European badgers (Meles meles) and pine martens (Martes martes). A large portion of these may be from hedgehog carcasses, especially roadkill. However, hedgehogs tend to be absent from areas where badgers are numerous.
Eurasian eagle-owls (Bubo bubo) and golden eagles (Aquila chrysaetos) are the only regular avian predators of this species and may even prefer them as prey. The owl, after grabbing the hedgehog by its face, tends to skin the mammal's prickly back with its talons before consumption, resulting in several hedgehog backs being found around eagle-owl roosts and nests. In Spain, reduction of European rabbit (Oryctolagus cuniculus) numbers due to rabbit haemorrhagic disease has made the European hedgehog one of the top preferred prey species for eagle-owls. Elsewhere, eagle-owls often prefer these hedgehogs to any other prey species, as the hedgehog can comprise up to 23% by number and 30.7% by biomass of eagle-owl prey remains. On the Swedish island of Gotland the golden eagle may take larger numbers of hedgehogs than any other prey due to an otherwise low diversity of native land mammals, although the introduction of European rabbits has shifted the eagle's prey preferences there.


The European hedgehog (Erinaceus europaeus), also known as the West European hedgehog or common hedgehog, is a hedgehog species native to Europe from Iberia and Italy northwards into Scandinavia and westwards into the British Isles. It is a generally common and widely distributed species that can survive across a wide range of habitat types. It is a well-known species, and a favourite in European gardens, both for its endearing appearance and its preference for eating a range of garden pests. While populations are currently stable across much of its range, it is declining severely in Great Britain where it is now Red Listed (classified as near to extinction).


The breeding season commences after hibernation. Pregnancies peak between May and July, though they have been recorded as late as September. Gestation is 31 to 35 days. The female alone raises the litter which typically numbers between four and six, though can range from two to ten. Studies have indicated that litter size may increase in more northern climes. The young are born blind with a covering of small spines. By the time they are 36 hours old, the second, outer coat of spines begins to sprout. By 11 days they can roll into a ball. Weaning occurs at around six weeks of age.


The northern cricket frog (Acris crepitans) is a species of small hylid frog native to the United States and northeastern Mexico. Despite being members of the tree frog family, they are not arboreal. It has two recognized subspecies.


Cricket frogs prefer the edges of slow-moving, permanent bodies of water. They prefer open, shallow waters with an abundance of aquatic vegetation. Large groups of them can often be found together along the muddy banks of shallow streams, especially during pre-migratory clustering. The northern cricket frog has been observed to hibernate upland, often at considerable distances from water. Given their small size and their large surface to volume ratio, it comes as no surprise that this species utilize microhabitats. There are various factors that influence microhabitat site selection for this species: temperature, proximity to water, shelter accessibility, etc.


Breeding generally occurs from May through July. The males call from emergent vegetation with a high-pitched, short, pebble-like call which is repeated at an increasing rate. The sound suggests pebbles being clicked together, much like a cricket, hence the name. One egg is laid at a time, generally attached to a piece of vegetation. The 14 millimetres (0.55 in) tadpoles hatch in only a few days, and undergo metamorphosis in early fall. Maturity is usually reached in less than a year.


Among the 22 species of the genus Macaca that are found in southern and eastern Asia as well as northwestern Africa, the Formosan macaque is the only species endemic to the island of Taiwan.
Formosan rock macaques live in mixed coniferous-hardwood temperate forest, as well as bamboo and grassland at 100-3600m (328-11,812 ft). The social structure of macaques is generally characterized as often occurring as a large stable multimale-multifemale troop. Formosan macaque is considered to be female-bonded which is similar to other species in the genus Macaca. Based on the study of Hsu and Lin, the average overall sex ratio was approximately 1:1, and the average adult sex ratio was close to 0.53.  Solitary adult males accounted for 5% of the entire population, and they were seen interacting with social troops especially during mating season. They communicate using visual signals and sounds. They will "scream" when non-group members come near them. Group members usually respond using a "kyaw-kyaw" sound.
Rock macaques are diurnal, arboreal, and terrestrial. They usually stay in trees and less so on the ground. They rest in forest and forage in grasslands.  Their diet consists of fruits, tender leaves, buds, grass stems, insects, snails, and bird eggs.


The Formosan rock macaque gives birth to a single offspring. During estrus, the perineum of the female swells at the base of the tail, and there is also swelling along the thighs.  Their mating season is from October to January.  Gestation may last about five and a half months.  Females give birth to babies between spring and summer. Females are entirely responsible for nursing.  Youngsters are carried in mother's arms for 2–3 months.  Not until one year old, will youngsters be fully separated from their parents carrying.


Brown bears were once native to Europe, much of Asia, the Atlas Mountains of Africa, and North America, but are now extirpated in some areas, and their populations have greatly decreased in other areas. There are approximately 200,000 brown bears left in the world. The largest populations are in Russia with 120,000, the United States with 32,500, and Canada with around 25,000. Brown bears live in Alaska, east through the Yukon and Northwest Territories, south through British Columbia and through the western half of Alberta. The Alaskan population is estimated at a healthy 32,000 individuals. In the lower 48 states, they are repopulating slowly, but steadily along the Rockies and the western Great Plains.
In Europe, in 2010, there were 14,000 brown bears in ten fragmented populations, from Spain (estimated at only 20–25 animals in the Pyrenees in 2010, in a range shared between Spain, France and Andorra, and some 210 animals in Asturias, Cantabria, Galicia and León, in the Picos de Europa and adjacent areas in 2013) in the west, to Russia in the east, and from Sweden and Finland in the north to Romania (5000–6000), Bulgaria (900–1200), Slovakia (with about 600–800 animals), Slovenia (500–700 animals) and Greece (with about 200 animals) in the south.
In Asia, brown bears are found primarily throughout Russia, thence more spottily southwest to parts of the Middle East, including almost all parts of Kurdistan, to as far south as southwestern Iran, and to the southeast in Northeast China. Brown bears are also found in Western China, Kyrgyzstan, North Korea, Pakistan, Afghanistan and India. They can also be found on the Japanese island of Hokkaidō, which holds the largest number of non-Russian brown bears in eastern Asia with about 2,000–3,000 animals.
This species inhabits the broadest range of habitats of any living bear species.
They seem to have no altitudinal preferences and have been recorded from sea level to an elevation of 5,000 m (16,000 ft) (the latter in the Himalayas). In most of their range, brown bears generally seem to prefer semiopen country, with a scattering of vegetation that can allow them a resting spot during the day. However, they have been recorded as inhabiting every variety of northern temperate forest known to occur.


The brown bear is one of the most omnivorous animals in the world and has been recorded as consuming the greatest variety of foods of any bear. Throughout life, this species is regularly curious about the potential of eating virtually any organism or object that they encounter. Food that is both abundant and easily accessed or caught is preferred. Their jaw structure has evolved to fit their dietary habits. Their diet varies enormously throughout their differing areas based on opportunity.
Despite their reputation, most brown bears are not highly carnivorous, as they derive up to 90% of their dietary food energy from vegetable matter. They often feed on a variety of plant life, including berries, grasses, flowers, acorns and pine cones, as well as fungi such as mushrooms. Among all bears, brown bears are uniquely equipped to dig for tough foods such as roots, bulbs and shoots. They use their long, strong claws to dig out earth to reach the roots and their powerful jaws to bite through them. In spring, winter-provided carrion, grasses, shoots, sedges, moss and forbs are the dietary mainstays for brown bears internationally. Fruits, including berries, become increasingly important during summer and early autumn. Roots and bulbs become critical in autumn for some inland bear populations if fruit crops are poor. They will also commonly consume animal matter, which in summer and autumn may regularly be in the form of insects, larvae and grubs, including beehives. Bears in Yellowstone eat an enormous number of moths during the summer, sometimes as many as 40,000 Army cutworm moths in a single day, and may derive up to half of their annual food energy from these insects. Brown bears living near coastal regions will regularly eat crabs and clams. In Alaska, bears along the beaches of estuaries regularly dig through the sand for clams. This species may eat birds and their eggs, including almost entirely ground- or rock-nesting species. The diet may be supplemented by rodents or similar smallish mammals, including marmots, ground squirrels, mice, rats, lemmings and voles. With particular regularity, bears in Denali National Park will wait at burrows of Arctic ground squirrels hoping to pick off a few of the 1 kg (2.2 lb) rodents.
In the Kamchatka peninsula and several parts of coastal Alaska, brown bears feed mostly on spawning salmon, whose nutrition and abundance explain the enormous size of the bears in these areas. The fishing techniques of bears are well-documented. They often congregate around falls when the salmon are forced to breach the water, at which point the bears will try to catch the fish in mid-air (often with their mouths). They will also wade into shallow waters, hoping to pin a slippery salmon with their claws. While they may eat almost all the parts of the fish, bears at the peak of spawning, when there is usually a glut of fish to feed on, may eat only the most nutrious parts of the salmon (including the eggs and head) and then indifferently leave the rest of the carcass to scavengers, which can include red foxes, bald eagles, common ravens and gulls. Despite their normally solitary habits, brown bears will gather rather closely in numbers at good spawning sites. The largest and most powerful males claim the most fruitful fishing spots and bears (especially males) will sometimes fight over the rights to a prime fishing spot.
Beyond the regular predation of salmon, most brown bears are not particularly active predators. While perhaps a majority of bears of the species will charge at large prey at one point in their lives and most eat carrion, many predation attempts start with the bear clumsily and half-heartedly pursuing the prey and end with the prey escaping alive. On the other hand, some brown bears are quite self-assured predators who habitually pursue and catch large prey items. Such bears are usually taught how to hunt by their mothers from an early age. Large mammals preyed on can include various ungulate species such as elk, moose, caribou, muskoxen, wild boar, mountain sheep and mountain goats. When brown bears attack these large animals, they usually target young or infirm ones, as they are easier to catch. Typically when hunting (especially with young prey), the bear pins its prey to the ground and then immediately tears and eats it alive. It will also bite or swipe some prey to stun it enough to knock it over for consumption. To pick out young or infirm individuals, bears will charge at herds so the slower-moving and more vulnerable individuals will be made apparent. Brown bears may also ambush young animals by finding them via scent. When emerging from hibernation, brown bears, whose broad paws allow them to walk over most ice and snow, may pursue large prey such as moose whose hooves cannot support them on encrusted snow. Similarly, predatory attacks on large prey sometimes occur at riverbeds, when it is more difficult for the prey specimen to run away due to muddy or slippery soil. On rare occasions, while confronting fully-grown, dangerous prey, bears kill them by hitting with their powerful forearms, which can break the necks and backs of large creatures such as adult moose and adult bison. They also feed on carrion, and use their size to intimidate other predators, such as wolves, cougars, tigers, and American black bears from their kills. Carrion is especially important in the early spring (when the bears are emerging from hibernation), much of it comprising winter-killed big game. Cannibalism is not unheard of, though predation is not normally believed to be the primary motivation when brown bears attack each other.
When forced to live in close proximity with humans and their domesticated animals, bears may potentially predate any type of domestic animal. Among these, domestic cattle are sometimes exploited as prey. Cattle are bitten on the neck, back or head and then the abdominal cavity is opened for eating. Plants and fruit farmed by humans are readily consumed as well, including corn, wheat, sorghum, melons and any form of berries. They will also feed at domestic bee yards, readily consuming both honey and the brood (grubs and pupae) of the honey bee colony. Human foods and trash or refuse is eaten when possible. When an open garbage dump was kept in Yellowstone, brown bears were one of the most voracious and regular scavengers. The dump was closed after both brown and American black bears came to associate humans with food and lost their natural fear of them.


Adult bears are generally immune to predatory attacks except from tigers and other bears. Siberian tigers prefer preying on young Ussuri brown bears, but smaller adult female brown bears outside their dens may also be taken, generally when lethargic from hibernation. Of 44 recorded encounters between the two predators, 20 resulted in confrontations; in 50% of these, the bears were killed, in 27% the tigers were killed, and 23% of the cases ended with both animals surviving and parting ways. Some bears emerging from hibernation seek out tigers in order to steal their kills. Some large brown bears may actually benefit from the tiger's presence by appropriating tiger kills that the bears may not be able to successfully hunt themselves and follow tiger tracks. Geptner et al. (1972) stated bears are generally afraid of tigers and change their path after coming across tiger trails. In the winters of 1970–1973, Yudakov and Nikolaev recorded 1 case of brown bear showing no fear of the tigers and another case of brown bear changing path upon crossing tiger tracks. Other researchers have observed bears following tiger tracks for various reasons.
Brown bears regularly intimidate wolves to drive them away from their kills. In Yellowstone National Park, bears pirate wolf kills so often, Yellowstone's Wolf Project director Doug Smith wrote, "It's not a matter of if the bears will come calling after a kill, but when." Despite the high animosity between the two species, most confrontations at kill sites or large carcasses end without bloodshed on either side. Though conflict over carcasses is common, on rare occasions, the two predators tolerate each other on the same kill. To date, there is a single case of fully-grown wolves being killed by a grizzly bear. Given the opportunity, however, both species will prey on the other's cubs. Conclusively, the individual power of the bear against the collective strength of the wolf pack usually results in a long battle for kills or domination.
In some areas, grizzly bears also regularly displace cougars from their kills. Cougars kill small bear cubs on rare occasions, but there was one report of a bear killing a cougar of unknown age and condition between 1993 and 1996. Smaller carnivorous animals, including coyotes, wolverines, lynxes, and any other sympatric carnivores or raptorial birds, are dominated by grizzly bears and generally avoid direct interactions with them, unless attempting to steal scraps of food. However, wolverines have been persistent enough to fend off a grizzly bear as much as ten times their weight off a kill. There is one record of a golden eagle preying on a brown bear cub.
Brown bears usually dominate other bear species in areas where they coexist. Due to their smaller size, American black bears are at a competitive disadvantage to grizzly bears in open, unforested areas. Although displacement of black bears by grizzly bears has been documented, actual interspecific killing of black bears by grizzlies has only occasionally been reported. Confrontation is mostly avoided due to the black bear's diurnal habits and preference for heavily forested areas, as opposed to the grizzly's largely nocturnal habits and preference for open spaces. Brown bears may also kill Asian black bears, though the latter species probably largely avoids conflicts with the brown bear, due to similar habits and habitat preferences to the American black species. They will eat the fruit dropped by the Asian black bear from trees, as they themselves are too large and cumbersome to climb.  Improbably, in the Himalayas Brown bears are reportedly intimidated by Asian black bears in confrontations.
There has been a recent increase in interactions between brown bears and polar bears, theorized to be caused by climate change. Brown and grizzly bears have been seen moving increasingly northward into territories formerly claimed by polar bears. They tend to dominate polar bears in disputes over carcasses, and dead polar bear cubs have been found in brown bear dens.


The brown bear (Ursus arctos) is a large bear species found across Eurasia and North America. In North America, the populations of brown bears are called grizzly bears, while the subspecies that inhabits the Kodiak Islands of Alaska is known as the Kodiak bear. It is one of the largest living terrestrial members of the order Carnivora, rivaled in size only by its closest relative, the polar bear (Ursus maritimus), which is much less variable in size and slightly bigger on average. The brown bear's range includes parts of Russia, Central Asia, the Himalayas, China, Canada, the United States, Hokkaido, Scandinavia, Finland, the Balkans, the Picos de Europa and the Carpathian region (especially Romania), Iran, Anatolia, and the Caucasus. The brown bear is recognized as a national and state animal in several European countries.
While the brown bear's range has shrunk, and it has faced local extinctions across its wide range, it remains listed as a least concern species by the International Union for Conservation of Nature (IUCN) with a total estimated  population in 2017 of 110,000. As of 2012, this and the American black bear are the only bear species not classified as threatened by the IUCN, though the large sizes of both bears may be a disadvantage due to increased competition with humans. Populations that were hunted to extinction in the 19th and 20th centuries are the Atlas bear of North Africa and the Californian, Ungavan and Mexican populations of the grizzly bear of North America. Many of the populations in the southern parts of Eurasia are highly endangered as well. One of the smaller-bodied forms, the Himalayan brown bear, is critically endangered, occupying only 2% of its former range and threatened by uncontrolled poaching for its body parts. The Marsican brown bear of central Italy is one of several currently isolated populations of the Eurasian brown bear and is believed to have a population of just 50 to 60 bears.


The mating season is from mid-May to early July, shifting later the further north the bears are found. Being serially monogamous, brown bears remain with the same mate from a couple of days to a couple of weeks. Outside of this narrow time frame, adult male and female brown bears show no sexual interest in each other. Females mature sexually between the age of four and eight years of age, with an average age at sexual maturity of 5.2–5.5 years old, while males first mate about a year later on average, when they are large and strong enough to successfully compete with other males for mating rights. Males will try to mate with as many females as they can; usually a successful one mates with two females in a span of one to three weeks. The adult female brown bear is similarly promiscuous, mating with up to four, rarely even eight, males while in heat and potentially breeding with two males in a single day. Females come into oestrus on average every three to four years, with a full range of 2.4 to 5.7 years. The urine markings of a female in oestrus can attract several males via scent. Paternity DNA tests have shown that littermates do not share the same father in up to 29% of litters. Dominant males may try to sequester a female for her entire oestrus period of approximately two weeks, but usually are unable to retain her for the entire time. Copulation is vigorous and prolonged and can last up to an hour, although the mean time is about 23–24 minutes.
Males take no part in raising their cubs – parenting is left entirely to the females. Through the process of delayed implantation, a female's fertilized egg divides and floats freely in the uterus for six months. During winter dormancy, the fetus attaches to the uterine wall. The cubs are born eight weeks later while the mother sleeps. If the mother does not gain enough weight to survive through the winter while gestating, the embryo does not implant and is reabsorbed into the body. There have been cases of brown bears with as many as six cubs, although the average litter size is one to three, with more than four being considered uncommon. There are records of females sometimes adopting stray cubs or even trading or kidnapping cubs when they emerge from hibernation (a larger female may claim cubs away from a smaller one). Older and larger females within a population tend to give birth to larger litters. The size of a litter also depends on factors such as geographic location and food supply. At birth, the cubs are blind, toothless and hairless and may weigh from 350 to 510 g (0.77 to 1.12 lb), again reportedly based on the age and condition of the mother. They feed on their mother's milk until spring or even early summer, depending on climate conditions. At this time, the cubs weigh 7 to 9 kg (15 to 20 lb) and have developed enough to follow her over long distances and begin to forage for solid food.
The cubs are fully dependent on the mother and a close bond is formed. During the dependency stage, the cubs learn (rather than inherit as instincts from birth) survival techniques, such as which foods have the highest nutritional value and where to obtain them; how to hunt, fish and defend themselves; and where to den. Increased brain size in large carnivores has been positively linked to whether a given species is solitary, as is the brown bear, or raises their offspring communally, thus female brown bears have relatively large, well-developed brains, presumably key in teaching behavior. The cubs learn by following and imitating their mother's actions during the period they are with her. Cubs remain with their mother for an average of 2.5 years in North America, uncommonly being independent as early as 1.5 years of age or as late as 4.5 years of age. The stage at which independence is attained may generally be earlier in some parts of Eurasia, as the latest date which mother and cubs were together was 2.3 years, most families separated in under two years in a study from Hokkaido and in Sweden most cubs on their own were still yearlings. Brown bears practice infanticide, as an adult male bear may kill the cubs of a female bear. When an adult male brown bear kills a cub, it is usually because he is trying to bring the female into oestrus, as she will enter that state within two to four days after the death of her cubs. Cubs flee up a tree, if available, when they see a strange male bear and the mother often successfully defends them, even though the male may be twice as heavy as she, although females have been known to die in these confrontations.


The brown bear has a naturally long life. Wild females have been observed reproducing up to 28 years of age, which is the oldest known age for reproduction of any ursid in the wild. The peak reproductive age for females ranges from four to 20 years old. The lifespan of brown bears of both sexes within minimally hunted populations is estimated at an average of 25 years. The oldest wild brown bear on record was nearly 37 years old. The oldest recorded female in captivity was nearly 40 years old, while males in captivity have been verified to live up to 47 years, with one captive male possibly attaining 50 years of age.
While male bears potentially live longer in captivity, female grizzly bears have a greater annual survival rate than males within wild populations per a study done in the Greater Yellowstone Ecosystem. Annual mortality for bears of any age is estimated at 10% in most protected areas; however, the average annual mortality rate rises to an estimated 38% in hunted populations. Around 13% to 44% of cubs die within their first year even in well-protected areas. Mortality rates of 75–100% among the cubs of any given year are not uncommon. Beyond predation by large predators including wolves, Siberian tigers and other brown bears, starvation and accidents also claim the lives of cubs. Studies have indicated that the most prevalent source of mortality for first-year cubs is malnutrition. By the second and third years of their lives, the annual mortality rate among cubs in the care of their mothers drops to 10-15%.
Even in populations living in protected areas, humans are still the leading cause of mortality for brown bears. The largest amount of legalized brown bear hunting occurs in Canada, Finland, Russia, Slovakia and Alaska. Hunting is unregulated in many areas within the range of the brown bear. Even where hunting is legally permitted, most biologists feel that the numbers hunted are excessive considering the low reproduction rate and sparse distribution of the species. Brown bears are also killed in collisions with automobiles, which is a significant cause of mortality in the United States and Europe.


During the summer, the tricolored bat will roost in tree foliage or buildings, with females alone or in maternity colonies of up to thirty individuals. Trees used for this purpose include oak, maple, the eastern cottonwood, and American tulip tree. Males are solitary and do not form colonies. In Nova Scotia, researchers discovered nearly one hundred roosts of this species, finding that all sampled individuals were roosting not in tree foliage, but rather in a species of beard lichen, Usnea trichodea. This was thought to be the first documentation of a bat using beard lichen as a roosting substrate. It was speculated that the tricolored bat may use the lichen to ward off parasites. Usnic acid, which has anti-insect and anti-bacterial properties, naturally occurs in beard lichens, and no ectoparasites (external parasites) have been documented on the tricolored bat in Nova Scotia.
In the winter, the tricolored bat hibernates in mines, caves, or other human structures. A years-long study of a mine in the US state of Nebraska found that in the summer, the mine was mostly occupied by males. Total number of tricolored bats using the mine at one time ranged from zero to forty-three. Bats were in a state of torpor from November to April. More bats used the mine as a roost in the winter than in the summer. In another abandoned mine in the US state of Indiana, researchers found that the tricolored bat roosts solitarily during hibernation for the majority of the time (96.8% of observations were singletons). During hibernation, males lose an average of 2.65 g (0.093 oz), while females lose an average of 2.5 g (0.088 oz).


The tricolored bat is insectivorous, consuming small prey of 4–10 mm (0.16–0.39 in) in length. Prey taxa include mosquitoes, beetles, ants, moths, and cicadas. It forages with slow, erratic flight in areas near water or forest edges. It is one of the first bat species to begin foraging each night. It navigates and searches for prey via echolocation (sonar). Its echolocation calls are at a high frequency; visual renderings of the calls show a distinctive hook-shaped call profile, with the lowest frequencies (bottom of the hook shape) at 42 kHz.


The tricolored bat's natural predators include the northern leopard frog, birds of prey, raccoons, snakes, skunks, and prairie voles. Feral cats will also catch and kill them as they leave their hibernacula (cave or mine used for hibernation). There are also records of it being attacked by the hoary bat. The tricolored bat is the host to several species of endoparasites (internal parasites) and ectoparasites. Oocysts (spores) of an Eimeria species (Eimeria heidti ) have been recovered from its guano (feces).
The tricolored bat has experienced severe population decline as a result of the fungal disease white-nose syndrome, which arrived in the US in 2006, with losses of 70% and greater detected in multiple US states. The disease kills bats by colonizing their skin during the winter, causing them to arouse from torpor and burn through their limited fat reserves. Though its population experienced dramatic reduction, subsequent studies have found that their numbers may be stabilizing, though hibernacula where many individuals once roosted may only host fewer than five bats, or even one solitarily.


The tricolored bat (Perimyotis subflavus) is a species of microbat native to eastern North America. Formerly known as the eastern pipistrelle, based on the errant belief that it was closely related to European Pipistrellus species, the closest known relative of the tricolored bat is now recognized as the canyon bat. Its common name "tricolored bat" derives from the coloration of the hairs on its back, which have three distinct color bands. It is the smallest bat species in the eastern and midwestern US, with individuals weighing only 4.6–7.9 g (0.16–0.28 oz). This species mates in the fall before hibernation, though due to sperm storage, females do not become pregnant until the spring. Young are born helpless, though rapidly develop, flying and foraging for themselves by four weeks old. It has a relatively long lifespan, and can live nearly fifteen years.
In the summer, females roost in small groups and males roost solitarily in tree foliage or beard lichen. It eats a diverse array of insects, foraging with a slow, erratic flight and navigating via echolocation. Though once considered one of the most common bat species in its range, its populations have declined rapidly since 2006 with the introduction of the fungal disease white-nose syndrome. It was listed as an endangered species in 2012 in Canada, and has been petitioned for inclusion on the US endangered species list. Along with the silver-haired bat, the tricolored bat is one of two bat species whose rabies variants have most frequently been implicated in human rabies deaths in the US, with sixteen deaths from 1958–2000.


The tricolored bat is a seasonal breeder, with copulation (mating) occurring in the fall before hibernation. Ovulation does not occur until the spring, however, and females store the males' sperm in their uteruses through the winter. Gestation (pregnancy) length is about forty-four days, with females giving birth in June or July. The litter size is typically two individuals. As newborns, the combined mass of twin pups can be as great as 58% of the mother's postpartum mass. At birth, the young lack fur and their eyes are closed. The mother leaves the offspring behind at the roost while she forages at night. Offspring develop rapidly, beginning to fly at three weeks old. By four weeks old, they are foraging for themselves. Young do not reach sexual maturity in their first fall; they do not breed until their second fall.
Individuals can live at least 14.8 years in the wild; juveniles have higher mortality rates than adults, and females have higher mortality rates than males.


The northern crested newt, great crested newt or warty newt (Triturus cristatus) is a newt species native to Great Britain, northern and central continental Europe and parts of Western Siberia. It is a large newt, with females growing up to 16 cm (6.3 in) long. Its back and sides are dark brown, while the belly is yellow to orange with dark blotches. Males develop a conspicuous jagged crest on their back and tail during the breeding season.
The northern crested newt spends most of the year on land, mainly in forested areas in lowlands. It moves to aquatic breeding sites, mainly larger fish-free ponds, in spring. Males court females with a ritualised display and deposit a spermatophore on the ground, which the female then picks up with her cloaca. After fertilisation, a female lays around 200 eggs, folding them into water plants. The larvae develop over two to four months before metamorphosing into terrestrial juveniles (efts). Both larvae and land-dwelling newts mainly feed on different invertebrates.
Several of the northern crested newt's former subspecies are now recognised as separate species in the genus Triturus. Its closest relative is the Danube crested newt (T. dobrogicus). It sometimes forms hybrids with some of its relatives, including the marbled newt (T. marmoratus). Although today the most widespread Triturus species, the northern crested newt was probably confined to small refugial areas in the Carpathians during the Last Glacial Maximum.
While the International Union for Conservation of Nature lists it as Least Concern species, populations of the northern crested newt have been declining. The main threat is habitat destruction, for example, through urban sprawl. The species is listed as a European Protected Species.


Outside of the breeding season, northern crested newts are mainly forest-dwellers. They prefer deciduous woodlands or groves, but conifer woods are also accepted, especially in the far northern and southern ranges. In the absence of forests, other cover-rich habitats, as for example hedgerows, scrub, swampy meadows, or quarries, can be inhabited.
Preferred aquatic breeding sites are stagnant, mid- to large-sized, unshaded water bodies with abundant underwater vegetation but without fish (which prey on larvae). Typical examples are larger ponds, which need not be of natural origin; indeed, most ponds inhabited in the United Kingdom are human-made. Examples of other suitable secondary habitats are ditches, channels, gravel pit lakes, or garden ponds. Other newts that can sometimes be found in the same breeding sites are the smooth newt (Lissotriton vulgaris), the palmate newt (L. helveticus), the Carpathian newt (L. montadoni), the alpine newt (Ichthyosaura alpestris) and the marbled newt (Triturus marmoratus).
The northern crested newt is generally a lowland species but has been found up to 1,750 m (5,740 ft) in the Alps.


The northern crested newt is a relatively large newt species. Males usually reach 13.5 cm (5.3 in) total length, while females grow up to 16 cm (6.3 in). Rare individuals of 20 cm (7.9 in) have been recorded. Other crested newt species are more stockily built; only the Danube crested newt (T. dobrogicus) is more slender. Body shape is correlated with skeletal build: The northern crested newt has 15 rib-bearing vertebrae, only the Danube crested newt has more (16–17), while the other, more stocky Triturus species have 14 or less.
The newts have rough skin, and are dark brown on the back and sides, with black spots and heavy white stippling on the flanks. The female has a yellow line running along the lower tail edge. The throat is mixed yellow–black with fine white stippling, the belly yellow to orange with dark, irregular blotches.
During the aquatic breeding season, males develop crest up to 1.5 cm (0.59 in) high, which runs along the back and tail but is interrupted at the tail base. It is heavily indented on the back but smoother on the tail. Also during breeding season, the male's cloaca swells and it has a blue–white flash running along the sides of the tail. Females do not develop a crest.


The northern crested newt was described as Triton cristatus by Josephus Nicolaus Laurenti in 1768. As Linnaeus had already used the name Triton for a genus of sea snails ten years before, Constantine Samuel Rafinesque introduced the new genus name Triturus in 1815, with T. cristatus as type species.
Over 40 scientific names introduced over time are now considered as synonyms, including Lacertus aquatilis, a nomen oblitum published four years before Laurenti's species name. Hybrids resulting from the cross of a crested newt male with a marbled newt (Triturus marmoratus) female were mistakenly described as distinct species Triton blasii, and the reverse hybrids as Triton trouessarti.
T. cristatus was long considered as a single species, the "crested newt", with several subspecies. Substantial genetic differences between these subspecies were, however, noted and eventually led to their recognition as full species, often collectively referred to as "T. cristatus species complex". There are now seven accepted species of crested newts, of which the northern crested newt is the most widespread.


The northern leopard frog (Lithobates pipiens or Rana pipiens) is a species of leopard frog from the true frog family, native to parts of Canada and the United States. It is the state amphibian of Minnesota and Vermont.


Northern leopard frogs have a wide range of habitats. They are found in permanent ponds, swamps, marshes, and slow-moving streams throughout forest, open, and urban areas. They normally inhabit water bodies with abundant aquatic vegetation. In the summer, they often abandon ponds and move to grassy areas and lawns. They are well adapted to cold and can be found above 3,000 m (9,800 ft) above mean sea level. Males make a short, snore-like call from water during spring and summer. The northern leopard frog breeds in the spring (March–June). Up to 6500 eggs are laid in water, and tadpoles complete development within the breeding pond. Tadpoles are light brown with black spots, and development takes 70–110 days, depending on conditions. Metamorph frogs are 2–3 cm (0.79–1.18 in) long and resemble the adult.
This species was once quite common through parts of western Canada and the United States until declines started occurring during the 1970s. Although the definitive cause of this decline is unknown, habitat loss and fragmentation, environmental contaminants, introduced fish, drought, and disease have been proposed as mechanisms of decline and are likely preventing species' recovery in many areas. Many populations of northern leopard frogs have not yet recovered from these declines.
Northern leopard frogs are preyed upon by many different animals, such as snakes, raccoons, other frogs, and even humans. They do not produce distasteful skin secretions and rely on speed to evade predation.
They eat a wide variety of animals, including crickets, flies, worms, and smaller frogs. Using their large mouths, they can even swallow birds and garter snakes. In one case, a bat was recorded as prey of this frog. This species is similar to the pickerel frog (Lithobates palustris) and the southern leopard frog (Lithobates sphenocephalus).


The northern leopard frog is a fairly large species of frog, reaching about 11 cm (4.3 in) in snout-to-vent length. It varies from green to brown in dorsal color, with large, dark, circular spots on its back, sides, and legs. Each spot is normally bordered by a lighter ring. A pair of dorsolateral folds starting from the back of the eye runs parallel to each other down the back. These dorsolateral folds are often lighter or occasionally pinkish in colour. Also, a pale stripe runs from the nostril, under the eye and tympanum, terminating at the shoulder. The ventral surface is white or pale green. The iris is golden and toes are webbed.
Tadpoles are dark brown or grey, with light blotches on the underside. The tail is pale tan.


Snowshoe hares are primarily found in boreal forests and upper montane forests; within these forests, they favor habitats with a dense shrub layer.
In the Pacific Northwest, snowshoe hares occupy diverse habitats, including mature conifers (mostly Douglas-fir [Pseudotsuga menziesii] and variants), immature conifers, alder (Alnus spp.)/salmonberry (Rubus spectabilis), Sitka spruce (Picea sitchensis)/salal (Gaultheria shallon), and cedar (Thuja spp.) swamps. In western Oregon, snowshoe hares were present in brush patches of vine maple (Acer circinatum), willows (Salix spp.), rhododendrons (Rhododendron spp.), and other shrubs.
In Utah, snowshoe hares used Gambel oak (Quercus gambelli) in the northern portion of the Gambel oak range. In the Southwest, the southernmost populations of snowshoe hares occur in
the Sangre de Cristo Mountains, New Mexico, in subalpine scrub: narrow bands of shrubby and prostrate conifers at and just below timberline that are usually composed of Engelmann spruce (Picea engelmannii), bristlecone pine (Pinus aristata), limber pine (P. flexilis), and/or common juniper (Juniperus communis).
In Minnesota, snowshoe hares use jack pine (P. banksiana) uplands, edges, tamarack (Larix laricina) bogs, black spruce (Picea mariana) bogs, and sedge (Carex spp.), alder, and scrub fens. In New England, snowshoe hares favor second-growth aspen (Populus spp.)-birch (Betula spp.) near conifers, but other forest types occupied by snowshoe hares include aspens, paper birch (B. papyrifera), northern hardwoods, red maple (A. rubrum), balsam fir (Abies balsamea), red
spruce (Picea rubens)-balsam fir, eastern hemlock (Tsuga canadensis), northern red oak (Quercus rubra), oak (Quercus spp.)-pine (Pinus spp.), eastern white pine (P. strobus)-northern red oak-red maple, and eastern white pine. Snowshoe hares also use shrub swamps dominated by buttonbush (Cephalanthus occidentalis), alders, and silky dogwood (Cornus ammomum). Further details on plant communities used by snowshoe hares in different regions are in Bittner and Rongstad.


The snowshoe hare (Lepus americanus), also called the varying hare or snowshoe rabbit, is a species of hare found in North America. It has the name "snowshoe" because of the large size of its hind feet. The animal's feet prevent it from sinking into the snow when it hops and walks. Its feet also have fur on the soles to protect it from freezing temperatures.
For camouflage, its fur turns white during the winter and rusty brown during the summer. Its flanks are white year-round. The snowshoe hare is also distinguishable by the black tufts of fur on the edge of its ears. Its ears are shorter than those of most other hares.
In summer, it feeds on plants such as grass, ferns, and leaves; in winter, it eats twigs, the bark from trees, and plants and, similar to the Arctic hare, has been known to occasionally eat dead animals. It can sometimes be seen feeding in small groups. This animal is mainly active at night and does not hibernate. The snowshoe hare may have up to four litters in a year, which average three to eight young. Males compete for females, and females may breed with several males.
A major predator of the snowshoe hare is the Canada lynx. Historical records of animals caught by fur hunters over hundreds of years show the lynx and hare numbers rising and falling in a cycle, which has made the hare known to biology students worldwide as a case study of the relationship between numbers of predators and their prey.


Like all leporids, snowshoe hares are crepuscular and nocturnal. They are shy and secretive and spend most of the day in shallow depressions, called forms, scraped out under clumps of ferns, brush thickets, and downed piles of timber. They occasionally use the large burrows of mountain beavers (Aplodontia rufa) as forms. Diurnal activity level increases during the breeding season. Juveniles are usually more active and less cautious than adults.
Snowshoe hares are active year-round. The breeding season for hares is stimulated by new vegetation and varies with latitude, location, and yearly events (such as weather conditions and phase of snowshoe hare population cycle). Breeding generally begins in late December to January and lasts until July or August . In northwestern Oregon, male peak breeding activity (as determined by testes weight) occurs in May and is at the minimum in November. In Ontario, the peak is in May and in Newfoundland, the peak is in June. Female estrus begins in March in Newfoundland, Alberta, and Maine, and in early April in Michigan and Colorado. First litters of the year are born from mid-April to May.
The gestation period is 35 to 40 days; most studies report 37 days as the average length of gestation. Litters average three to five leverets depending on latitude, elevation, and phase of population cycle, ranging from one to seven. Deep snow-pack increases the amount of upper-branch browse available to snowshoe hares in winter, and therefore has a positive relationship with the nutritional status of breeding adults. Litters are usually smaller
in the southern sections of their range since there is less snow. Newborns are fully furred, open-eyed, and mobile. They leave the natal form within a short time after birth, often within 24 hours. After leaving the birthplace, siblings stay near each other during the day, gathering once each evening to nurse. Weaning occurs at 25 to 28 days except for the last litter of the season, which may nurse for two months or longer.
Female snowshoe hares can become pregnant anytime after the 35th day of gestation. The second litter can therefore be conceived before the first litter is born (snowshoe hares have twin uteri). Pregnancy rates ranged from 78 to 100% for females during the period of first litter production, 82 to 100% for second litters, and for the periods of third and fourth litters pregnancy rates vary with population cycle. In Newfoundland, the average number of litters per female per year ranged from 2.9 to 3.5, and in Alberta the range was from 2.7 to 3.3. The number of litters per year varies with phase of population cycle (see below). In Alberta the average number of litters per year was almost 3 just after a population peak and 4 just after the population low. Females normally first breed as 1-year-olds. Juvenile breeding is rare and has only been observed in females from the first litter of the year and only in years immediately following a low point in the population cycle.
In Yukon, 30-day survival of radio-tagged leverets was 46%, 15%, and 43% for the first, second, and third litters of the year, respectively. There were no differences in mortality in plots with food added. The main proximate cause of mortality was predation by small mammals, including red squirrels (Tamiasciurus hudsonicus) and Arctic ground squirrels (Spermophilus parryii). Littermates tended to live or die together more often than by chance. Individual survival was negatively related to litter size and positively related to body size at birth. Litter size is negatively correlated with body size at birth.


Snowshoe hares require dense, brushy, usually coniferous cover; thermal and escape cover are especially important for young hares. Low brush provides hiding, escape, and thermal cover. Heavy cover 10 feet (3 m) above ground provides protection from avian predators, and heavy cover 3.3 feet (1 m) tall provides cover from terrestrial predators. Overwinter survival increases with increased cover. A wide variety of habitat types are used if cover is available. Base visibility in good snowshoe hare habitat ranges from 2% at 16.5 feet (5 m) distance to 0% at 66 feet (20 m). Travel cover is slightly more open, ranging from 14.7% visibility at 16.5 feet (5 m) to 2.6% at 66 feet (20 m). Areas with horizontal vegetation density of 40 to 100% at 50 feet (15 m) are adequate snowshoe hare habitat in Utah.


Northern populations of snowshoe hares undergo cycles that range from seven to 17 years between population peaks. The average time between peaks is approximately 10 years. The period of abundance usually lasts for two to five years, followed by a population decline to lower numbers or local scarcity. Areas of great abundance tend to be scattered. Populations do not peak simultaneously in all areas, although a great deal of synchronicity occurs in northern latitudes. From 1931 to 1948, the cycle was synchronized within one or two years over most of Canada and Alaska, despite differences in predators and food supplies. In central Alberta, low snowshoe hare density occurred in 1965, with 42 to 74 snowshoe hares per 100 acres (40 ha). The population peak occurred in November 1970 with 2,830 to 5,660 snowshoe hares per 100 acres (40 ha). In the southern parts of its range, snowshoe hare populations do not fluctuate radically.
Exclosure experiments in Alberta indicated browsing by snowshoe hares during population peaks has the greatest impact on palatable species, thus further reducing the amount of available foods. In this study, insufficient nutritious young browse was available to sustain the number of snowshoe hares present in the peak years (1971 and 1972) in winter.
The hare's fluctuating numbers are modelled by the Lotka–Volterra equations.


The plains zebra's range stops short of the Sahara from South Sudan and southern Ethiopia extending south along eastern Africa, as far as Zambia, Mozambique, and Malawi, before spreading into most southern African countries. They may have lived in Algeria in the Neolithic era. Plains zebras generally live in treeless grasslands and savanna woodlands, but can be found in a variety of habitats, both tropical and temperate. However, they are generally absent from deserts, dense rainforests, and permanent wetlands. They generally prefer Acacieae woodlands over Commiphora. They are water-dependent and live in more mesic environments than other African equids. They seldom wander 10–12 km (6.2–7.5 mi) from a water source. Zebras also live in elevations from sea level to 4,300 ft on Mount Kenya.
Depending on the population, zebra herds may be sedentary, being highly dense with small ranges, or migratory, being less populated with separate, extensive dry and wet home ranges. When migrating, zebras appear to rely on some memory of the locations where foraging conditions were best and may predict conditions months before their arrival.


Plains zebras primarily feed on grass; preferred species being Themeda triandra, Cynodon dactylon, Eragrostis superba and Cenchrus ciliaris. Zebra sometimes browse or dig for corms and rhizomes during the dry season. They appear to partial to eating scorched Colophospermum mopane and Pterocarpus rotundifolius, consuming both the leaves and twigs.
Plains zebras are adapted for grazing on both long, tough grass stems and newly emerging short grass. In some areas, it rarely feeds below 100–150 mm (3.9–5.9 in) to ground level. It ranges more widely than many other species, even into woodlands, and it is often the first grazing species to appear in a well-vegetated area. The flexible upper lip allows them to push plant material between the incisors to cut. Zebras have a less efficient digestive system than ruminants but food passage is twice as fast. Thus, zebras are less selective in foraging, but they do spend much time eating. The zebra is a pioneer grazer and prepares the way for more specialised grazers such as blue wildebeests and Thomson's gazelles.
The plains zebra's major predators are lions and spotted hyenas. Lions are most successful when targeting lone individuals, usually an old male while hyenas chase and isolate an individual from the group, usually a female or foal. Nile crocodiles also prey on zebras when they are near water. Less common predators include cheetahs and African wild dogs, which mostly hunt foals. When in the presence of a lion, zebras remain alert and stand in a semi-circle at as much as 100 m (330 ft) and no less than 50 m (160 ft). Stallions sometimes try to drive lions away with bluff charges. By contrast, zebras may approach cheetahs and wild dogs and a single hyena is allowed to come within a few metres. To escape from predators, an adult zebra can run at 60–70 km/h (37–43 mph). When being hunted by hyenas or wild dogs, a zebra harem stays close together and cooperates to protect threatened members, particularly the young. The harem stallion goes on the offensive and attacks the dogs or hyenas.