Northern goshawks are often near the top of the avian food chain in forested biomes but face competition for food resources from various other predators, including both birds and mammals. Comparative dietary studies have shown that mean sizes of prey, both in terms of its size relative to the raptor itself and absolute weight, for goshawks is relatively larger than in most buteonine hawks in North America and Europe. Studies show even buteonine hawks slightly larger than goshawks on average take prey weighing less than 200 g (7.1 oz) whereas average goshawk prey is usually well over such a mass. This is due largely to the much higher importance of microtine rodents to most buteonine hawks, which, despite their occasional abundance, are ignored by goshawks in most regions. Similarly, mean prey mass for sharp-shinned and Cooper's hawks in North America is between about 10 and 30% of their own mass, whereas the mean prey of American goshawks is between about 25 and 50% of their own mass and therefore are the goshawks takes prey that is on average relatively much larger. In many of the ecosystems that they inhabit, northern goshawks compete with resources with other predators, particularly where they take sizeable numbers of lagomorphs. About a dozen mammalian and avian predators in each area all primarily consume European rabbits and snowshoe hares alongside goshawks in the Iberian peninsula and the American boreal forest regions where these became primary staple foods. Like those co-habitant predators, the goshawk suffers declines during the low portion in the lagomorph's breeding cycles, which rise and fall cyclically every 10 to 12 years. However, even where these are primary food sources, the northern goshawk is less specialized than many (even Bubo owls, some of the more generalist avian predators become extremely specialized lagomorph hunters locally, to a greater extent than goshawks) and can alternate their food selection, often taking equal or greater numbers of tree squirrels and woodland birds. Due to this dietary variation, the northern goshawk is less affected than other raptorial birds by prey population cycles and tends to not be depleted by resource competition.
Despite their propensity to pursue relatively large prey and capability to pursue alternate prey, northern goshawks can be locally outcompeted for resources by species that are more adaptable and flexible, especially in terms of habitat and prey. Most northern buteonine hawks largely take small rodents such as voles (which are usually ignored by goshawks) but can adapt to nearly any other type of prey when the staple local rodent prey populations go down. Comparisons with goshawks and red-tailed hawk nesting in abutting areas of Arizona (other large common Buteos like Swainson's hawks (Buteo swainsonii) and ferruginous hawks (Buteo regalis) utilize open habitats and so do not come into conflict with goshawks) shows the red-tailed hawks as being able to take a broader range of prey than goshawks and nest in more varied habitats, the latter species being perhaps the most commonly seen, widespread and adaptable of diurnal American raptors. On occasion, goshawks are robbed of their prey by a diversity of other birds, including harriers, other hawks, eagles, falcons and even gulls.
Northern goshawks from North America are less prone to nesting outside of mature forests and take larger numbers of mammals as opposed to abundant birds than in Europe. This may be in part due to heavier competition from a greater diversity of raptors in North America. In Europe, the goshawk only co-exists with the much smaller sparrowhawk within its own genus, while in North America, it lives with the intermediately-sized Cooper's hawk. The latter species much more readily nests in semi-open and developed areas of North America than goshawks there and hunts a broad assemblage of medium-sized birds, whereas such prey is more readily available to male goshawks from Europe than to goshawks in North America. Although the Cooper's hawk usually avoids and loses individual contests against the larger goshawk, its adaptability has allowed it to become the most widespread and commonly found North American Accipiter. The slightly larger goshawks of Europe have been shown, in some but not all areas, to outcompete and possibly lower productivity of the slightly smaller common buzzard (Buteo buteo) when their ranges overlap. Usually, however, the dietary habits and nesting preferences are sufficiently distinct and thus effect neither buzzard or goshawk populations. Both can mutually be very common even when the other is present. On the other hand, American goshawks are slightly smaller on average than their European counterparts and can be up to 10% smaller in mass than red-tailed hawks. However, studies have indicated that the goshawk has, beyond its superior speed and agility, has stronger feet and a more forceful attack than that of the red-tailed hawk. All in all, individual competitions between red-tailed hawks and goshawks can go either way and neither is strongly likely to deter the other from nesting given their distinct nesting habitats. Other raptors, including most medium to large-sized owls as well as red-tailed hawks and falcons, will use nests built by northern goshawks, even when goshawks are still in the area.
To many other raptorial birds, the northern goshawk is more significant as a predatory threat than as competition. The northern goshawk is one of the most dangerous species to other raptors, especially to those considerably smaller than itself. In many cases, raptors of any age from nestlings to adults are taken around their nests but free-flying raptors too are readily taken or ambushed at a perch. One example is a study from northern England, the common kestrels (Falco tinnunculus), which average about 184 g (6.5 oz), recorded as prey at goshawk nests (mainly in March and April) numbered 139, a larger number than kestrels recorded alive in the spring in the same area. In the Veluwe province of the Netherlands, the percentage of nest of European honey buzzards (Pernis apivorus), weighing on average 760 g (1.68 lb), predated by goshawks increased from a little as 7.7% in 1981–1990 to 33% in 2000–2004. As their habitat preferences may overlap with goshawks, all other Accipiters encountered may be predated in multiple cases, including the 238 g (8.4 oz) Eurasian sparrowhawk, the 188 g (6.6 oz) levant sparrowhawk (Accipiter brevipes), the 136 g (4.8 oz) sharp-shinned hawk, the 122 g (4.3 oz) Japanese sparrowhawk (Accipiter gularis) and the 440 g (0.97 lb) Cooper's hawk.
Other assorted accipitrids of up to their own size to be predated by goshawks include the 747 g (1.647 lb) black kite (Milvus migrans), the 1,080 g (2.38 lb) red kite (Milvus milvus), the 712 g (1.570 lb) western marsh-harrier (Circus aeruginosus), the 316 g (11.1 oz) Montagu's harrier (Circus pygargus), the 390 g (14 oz) pallid harrier (Circus macrourus), the 835 g (1.841 lb) booted eagle (Hieraaetus pennatus) and Buteos of up to adults including the 776 g (1.711 lb) common buzzard, the 424 g (15.0 oz) broad-winged hawk (Buteo platypterus), the 610 g (1.34 lb) red-shouldered hawk (Buteo lineatus) and the 1,065 g (2.348 lb) red-tailed hawk. Even raptors somewhat larger than a northern goshawks have been considered as prey, although it is not clear whether adults are among the victims, including the 1,494 g (3.294 lb) osprey (Pandion haliaetus), 1,147 g (2.529 lb) crested honey-buzzard (Pernis ptilorhynchus) and the 1,370 g (3.02 lb) lesser spotted eagle (Clanga pomarina).
Outside of the accipitrid group, heavy predation on different varieties of raptorial birds by northern goshawks can continue unabated. Many types of owl are taken and in Europe, the northern goshawk is the second most prolific predator of owls behind the Eurasian eagle owl (Bubo bubo). In Bavaria, Germany, the 287 g (10.1 oz) long-eared owl (Asio otus) was the second most common prey species for nesting goshawks. In the Białowieża Forest of Poland, fairly high numbers of the 475 g (1.047 lb) tawny owl (Strix alucco) were taken. In all, some 18 species of owl have been recorded in the diet, ranging in size from the Eurasian (Glaucidium passerinum) and northern pygmy owls (Glaucidium gnoma) at 58.5 g (0.129 lb) and 61.8 g (2.18 oz), respectively, to all the large northern Strix owls including adults and even the 1,400 g (3.1 lb) great horned owl. Whether adults have ever been killed as prey though is unknown but goshawks have been known to kill great horned owls that they've found near their nests. In addition, about eight species of falcon have been identified in the foods of goshawks. Adult falcons of small species such as kestrels and merlins (Falco columbarius) can be overpowered quite easily if they can manage to surprise the prey. Larger falcons have turned up in the diet as well, including the 720 g (1.59 lb) prairie falcon (Falco mexicanus) and the 966 g (2.130 lb) saker falcon (Falco cherrug), although possible only nestlings of these species. Brief aerial skirmishes between goshawks and peregrine falcons (Falco peregrinus) have been described but neither species is known to have killed one another in the wild.  In Schleswig-Holstein, Germany, at least four small passerines species were recorded as nesting close to active goshawk nest, due to the incidental shelter that the fierce goshawks inadvertently provides from smaller raptors which are their main predators. Such raptors, including Eurasian kestrels, Eurasian sparrowhawks and long-eared owls, not only avoid goshawk activity where possible but also were found to have lower nest productivity any time they nested relatively close to goshawks per the study. A similar phenomenon, with goshawks inadvertently providing shelter to small passerines, has been recorded in North America as well.
Competition for northern goshawks can also come from mammalian carnivores. Martens, and to a lesser extent other weasels, are presumably one of their more major competitors as their diet often consists of similar prey primarily during spring and summer, tree squirrels and woodland birds, but little has been studied in terms of how the two types of predator effect each other. Most recorded interactions have been predatory, as the goshawk has been recorded preying on a dozen species, from the 122 g (4.3 oz) least weasel (Mustela nivalis) to the 1,700 g (3.7 lb) stone marten (Martes foina). Northern goshawks have also been recorded as feeding on much bigger predators such as the 5,775 g (12.732 lb) red fox (Vulpes vulpes), the 4,040 g (8.91 lb) raccoon dog (Nyctereutes procyonoides) and the 3,500 g (7.7 lb) striped skunk (Mephitis mephitis), but it is not clear whether these were actual kills, as many may be encountered as already dead carrion. Domestic carnivores are sometimes eaten, including dogs and cats, the latter of which has reportedly been taken alive by goshawks. The red fox is a surprisingly considerable competitor for resources with northern goshawks. It was found in Norway that goshawk numbers were higher when voles were at peak numbers, not due to voles as a food source but because foxes were more likely to eat the rodents and ignore grouse, whereas during low vole numbers the foxes are more likely to compete with goshawks over grouse as prey. A decrease of the fox population of Norway due to sarcoptic mange was found result in an increase of grouse numbers and, in turn, northern goshawks. In some areas, red foxes have been found to steal up to half of the goshawks’ kills.
Unlike the predators at the top of the avian food chain such as eagles and the largest owls, which are rarely endangered by predation as adults, the northern goshawk is itself susceptible to a fairly extensive range of predators. The most deadly are likely to be the Eurasian eagle owl and the great horned owl, which not only predate goshawks of any age and at any season but also opportunistically take over their own prior nests as their own nesting site. Of the two, the American horned owl nesting habits are more similar to goshawks, which most often consists of tree nests whereas the eagle owl usually nests in rock formations. Thus, the northern goshawk is more likely to victimized by the great horned owls, which can stage nightly ambushes and destroy an entire goshawk family as they pick off both adults and nestlings. In radio-tagging studies of adult and immature goshawks in the Great Lakes region and Arizona, up to half of the studied birds were killed by great horned owls at night, while the horned owls accounted for 40% of the nest failures in studies from Arizona and New Mexico. In comparison, in Schleswig-Holstein, 59% of reintroduced eagle owls used nests built by goshawks and no goshawk pairs could successfully nest within 500 m (1,600 ft) of an active eagle-owl nest. 18% of nest failures here positively were attributed to eagle owl predation, with another 8% likely due to eagle-owls. Other larger raptorial birds can threaten them. The golden eagle (Aquila chrysaetos) and the bald eagle (Haliaeetus leucocephalus) in North America, have killed wintering goshawks, but given the discrepancy in their habitat preferences, such cases are presumably rare. Other avian predators known to have successfully preyed on goshawks including adults (usually in singular cases) include white-tailed eagles (Haliaeetus albicilla), Bonelli's eagles (Aquila fasciata), eastern imperial eagles (Aquila heliaca), snowy owls (Bubo scandiacus), Ural owls (Strix uralensis) and red-tailed hawks.
The same mammalian predators that sometimes compete for food with northern goshawks also sometimes kill them, with the nestlings, fledglings and brooding females, all with impaired flight due to their wing feather moults, seemingly the most vulnerable. In one case, the American marten, which at 660 g (1.46 lb) is the smallest marten and is sometimes taken as prey by the goshawks, successfully ambushed and preyed on a brooding female goshawk. In Chequamegon-Nicolet National Forest of Wisconsin, the main source of mortality for northern goshawks are reintroduced fishers (Pekania pennanti), which are capable of killing many chicks, fledglings and brooding females. In contrast, in Europe, the pine marten (Martes martes) has only been known to prey on young goshawks still in the nest and not adults. Other mammals capable of climbing trees have been observed or inferred to predate goshawks, either mostly or entirely young in the nests, including wolverines (Gulo gulo), North American porcupines (Erethizon dorsatum), raccoons (Procyon lotor), bobcats (Lynx rufus) and American black bears (Ursus americanus). Overall, the range of nest predators is more extensive in North America than in Eurasia, in the latter continent most recorded nest depredations are by eagle owls, with martens and corvids usually only preying on goshawk nestlings when low food supplies cause the goshawks to have lower nest attendance (and presumably effect these predators to the extent that they take the risk of coming to the goshawk nest). Fledgling goshawks are also vulnerable to canids such as coyotes (Canis latrans), gray wolves (Canis lupus) and red foxes (Vulpes vulpes) as they may perch lower to the ground and are clumsier, more unsteady and less cautious than older birds. In one case, a goshawk that was ambushed and killed at a kill by a mangy vixen fox was able to lethally slash the windpipe of the fox, which apparently died moments after partially consuming the goshawk.
Apart from aforementioned predation events, northern goshawks have at times been killed by non-predators, including prey that turned the tables on their pursuer, as well as in hunting accidents. In one case, a huge group (or murder) of hooded crows heavily mobbed a goshawk that they caught in a relatively open spot, resulting in a prolonged attack that ended up killing the goshawk. In another instance, a goshawk drowned while attempting to capture a tufted duck (Aythya fuligula). One young goshawk managed to escape a red fox that had caught it with a chewed wing, only to drown in a nearby creek. Another, and rather gruesome, hunting mishap occurred when a goshawk caught a large mountain hare and, while attempting to hold it in place by grasping vegetation with its other foot, was torn in half.


The northern goshawk is one of the most extensively studied raptors in terms of its breeding habits. Adult goshawks return to their breeding grounds usually between March and April, but locally as early as February. If prey levels remain high, adults may remain on their breeding ground all year. Courtship flights, calls and even nest building has been recorded in Finland exceptionally in September and October right after young dispersed, whereas in most of Fennoscandia, breeding does not commence any earlier than March and even then only when it is a warm spring. Most breeding activity occurs between April and July, exceptionally a month earlier or later. Even in most areas of Alaska, most pairs have produced young by May. Courtship flights typical are above the canopy on sunny, relatively windless days in early spring with the goshawks’ long main tail feathers held together and the undertail coverts spread so wide to give them an appearance of having a short, broad-tail with a long dark strip extending from the center. Display flights not infrequently escalate into an undulating flight, similar to a wood pigeon but with sharper turns and descents, and are sometimes embellished with sky-dives that can cover over 200 m (660 ft). One study found undulating display flights more than three times more often done by males than females. After display flights have concluded, the male typically brings a prepared fresh prey item to the female as part of the courtship. In general, these displays are presumably to show (or reinforce) to the potential mate their health and prowess as breeding partner. Copulation is brief and frequent, ranging up to nearly 520 times per clutch (on average about 10 times a day or 100-300 throughout the season), and may be the male's way of ensuring paternity since he is frequently away gathering food by the time of egg-laying, although extra-pair copulation is extremely rare. Female solicits copulations by facing away from male with drooped wings and flared tail-coverts. The male, wings drooped and tail-coverts flared, drops from a branch to gain momentum, then swoops upward and mounts her back. Both birds usually call while mating. Fidelity studies from Europe show that about 80–90% of adult females breed with the same male in consecutive years, whereas up to 96% of males mate with the same female in consecutive years. In California, 72% of males retained relationship with the same mates in consecutive years while 70% of females did the same. Males intruding in Hamburg, Germany territories were in some cases not evicted and ended up mating with the female, with the male of the pair not stopping it. In migratory, northernmost populations, mate retention in consecutive years is low. Males are sometimes killed by females during courtship and encounters can be dangerous especially if he does not bring food to courtship and he often seems nervous withdrawing with a trill at a given chance.


Nesting areas are indefinite, a nest may be used for several years, also a nest built years prior may be used or an entirely new nest may be constructed. When nest constructing, the pair will often roost together. Males construct most new nests but females may assist somewhat if reinforcing old nests. While the male is building, the female perches in the vicinity, occasionally screaming, sometimes flying to inspect the nest. At other times, the female may take a more active role, or even the primary one, in new nest construction and this is subject to considerable individual variation. For the nesting tree, more than 20 species of conifer have been used including spruce, fir, larch, pine and hemlock. Broadleaf trees used including ash, alder, aspen, beech, birch, elm, hickory, hornbeam, lime, maple (including sycamore), oak, poplar, tamarack, wild cherry and willow. In some areas, the nests may be lined with hard pieces of bark and also with green sprigs of conifers. Often the tallest tree in a given stand is selected as the nest tree and this is often the dominant tree species within the given region and forest. Therefore, hardwood trees are usually used as the nesting tree in the eastern United States while conifers are usually used in the western United States. Most nests are constructed under the canopy or near the main fork of a tree and in North America, averaging nest height ranged from 5.8 m (19 ft) (in the Yukon) to 16.9 m (55 ft) (in New Mexico), elsewhere as in Europe average height is between 9 and 25 m (30 and 82 ft). In the dwarf trees of the tundra, nests have been found at only 1 to 2 m (3.3 to 6.6 ft) off the ground, and, in the tundra and elsewhere, very rarely on felled trees, stumps or on the ground. In some studies from North America up to 15% of nests are in dead trees but this is far rarer in Eurasia. More significant than species is the maturity and height of the nesting tree, its structure (which should have ample surface around the main fork) and, perhaps most significantly, little to no understory below it. Multiple studies note the habit of nests being built in forests close to clear-fellings, swamps and heaths, lakes and meadows, roads (especially light-use logging dirt roads), railways and swathes cut along power cables, usually near such openings there'd be prominent boulders, stones or roots of fallen trees or low branches to use as plucking points. Canopy cover averaged between 60 and 96% in Europe. As is typical in widely distributed raptors from temperate-zones, those from cold regions faced south, 65% in Alaska, 54% in Norway and also in high latitudes such as sky-forests of the Arizona Rockies, otherwise usually nests face north and east.
Nests, especially after initial construction, may average between 80 and 120 cm (31 and 47 in) in length and 50 to 70 cm (20 to 28 in) in width, and are around 20 to 25 cm (7.9 to 9.8 in) deep. After many uses, a nest can range up to 160 cm (63 in) across and 120 cm (47 in) in depth and can weigh up to a ton when wet. Northern goshawks may adopt nests of other species, common buzzards contributed 5% of nests used in Schleswig-Holstein, including unusually exposed ones on edges of woods and another 2% were built by common ravens or carrion crows, but 93% were built by the goshawks themselves. While colonizing peri-urban areas in Europe, they may displace Eurasian sparrowhawks not only from their territories but may actually try to use overly small sparrowhawk nests, usually resulting in nest collapse. One nest was used continuously by different pairs for a period of 17 years. A single pair may maintain up to several nests, usually up to two will occur in an area of no more than a few hundred meters. One nest may be used in sequential years, but often an alternate is selected. During an 18-year-study from Germany, many alternate nests were used, 27 pairs had two, 10 had 3, 5 had 4, one had five and one pair had as many as 11. Other regions where pairs had on average two nests were Poland, California and Arizona’s Kaibab Plateau. The extent of use of alternate nests is unknown as well as their benefit, but they may reduce significant levels of parasites and diseases within the nest. In central Europe, the goshawk's nest area can be as small 1 to 2 ha (2.5 to 4.9 acres) of woods and less than 10 hectares are commonplace. Usually only one active nest occurs per 100 ha (250 acres), are they avoid edges as nest sites and occupied nests are seldom less than 600 m (2,000 ft) apart.  The most closely spaced active nests by a separate pair on record was 400 m (1,300 ft) in central Europe, another case of two active nests 200 m (660 ft) apart in Germany was a possible case of polygamy.


The eggs are laid at 2- to 3-day intervals on average between April and June (usually May), taking up to 9 days for a clutch of 3–4 and 11 days for a clutch of 5. The eggs are rough, unmarked pale bluish or dirty white. In A. g, atricapillus, the average dimensions of the eggs are reported at 57.76 to 59.2 mm (2.274 to 2.331 in) in height by 44.7 to 45.1 mm (1.76 to 1.78 in) in width, with ranges of  52–66 mm (2.0–2.6 in) x 42–48 mm (1.7–1.9 in). In Spanish eggs, the average dimensions were 56.3 mm × 43 mm (2.22 in × 1.69 in) compared to  German ones, which averaged 57.3 mm × 44 mm (2.26 in × 1.73 in). Goshawks from Lapland, Finland lay the  largest known eggs at 62–65 mm (2.4–2.6 in) x 47–49.5 mm (1.85–1.95 in), while other Finnish goshawk eggs ranged from 59–64 mm (2.3–2.5 in) x 45–48 mm (1.8–1.9 in). Weight of the eggs average 59 g (2.1 oz) in America, 63 g (2.2 oz) in Great Britain and 50 to 60 g (1.8 to 2.1 oz) in Poland and Germany, with extreme weights from the latter nations of 35 to 75 g (1.2 to 2.6 oz). Clutch size almost always averages between 2 and 4 eggs, with a median around 3, rarely as few as 1 or as many 5–6 will be laid. In combination spring weather and prey population levels seem to drive both egg laying dates and clutch size. If an entire clutch is lost, a replacement can be laid within 15 to 30 days.


During incubation, females tend to become quieter and more inconspicuous. The mother can develop a brooding patch of up to 15 by 5 cm (5.9 by 2.0 in) on her underside. She may turn the eggs as frequently as every 30 to 60 minutes. Males may incubate as many as 1 to 3 hours, but usually less than an hour, early in incubation but rarely do so later on. During daylight females can do as much as 96% of the observed incubation. The incubation stage last for any time between 28 and 37 days (rarely up to 41 days in exceptionally big clutches), varying in different parts of the range. After hatching occurs, the male does not come directly to the nest but instead just delivers food (usually already plucked, beheaded or otherwise dismembered) to a branch near the nest which the female tears apart and shares between herself and the nestlings. Food deliveries by the male can be daily or as infrequent as every 3 to 5 days. In turn, the female must feed the young about twice a day in order for the chicks to avoid starvation. Caching of food has been recorded near the nest, but only before the young start feeding themselves. Food deliveries must average about 250 to 320 g (8.8 to 11.3 oz) per young goshawk per day for them to successfully fledge, or 700 to 950 g (1.54 to 2.09 lb) total daily and 60 to 100 kg (130 to 220 lb) throughout the season for an average sized clutch of around three. Females will also start capturing prey later on, but usually only after the young have already fledged. In Europe, female goshawks may press down on their nest if a human approaches, others may unobtrusively leave the nest, although are more reluctant to leave the nest late in incubation. In North America, the behavior of parent goshawks differs, as they often vigorously defend their territories fiercely from all intruders, including passing humans. The northern goshawk has a reputation as the most aggressive American raptor when the vicinity of their nest is approached. Here, when the nest is approached (especially soon after hatching) the goshawk will engage in their defensive kakking vocal display accompanied by exaggerated swooping in flight which quickly phases into a violent attack, potentially causing painful (but usually minor) injuries and blood loss. Research has indicated that attacks on humans are mostly done by adult females (more than 80% of the time) and are rarely pressed unless a person is by themselves. However, large groups and loud noise can appear to irritate the female and may cause her to attack the next lone person who comes near the nest. The higher aggression towards humans in North America than in Europe has been linked to both a more extensive range of potential nest predators for American goshawks causing them to develop a more aggressive display or the lower rates of persecution in America than in Europe, which may account for the relative shyness in the latter continent. Occasionally, both males and females have been recorded abandoning the nest and their mates. There are a few rare cases where males successfully reared up to 4 young after the female abandoned the nest or was killed between the 2 and 3rd week. Otherwise male will continue delivering prey but without the female all the nestlings will starve to death and the food simply rots. In cases where the male abandons the female and the brood, she may be able to successfully brood but usually only one nestling is likely to survive to fledge without the male's contribution of prey. At other times the mother may be replaced, sometimes forcefully, by another female, usually an older mature one. Exceptional cases of polygamy, with a male mating with two females, have been reported in Germany and The Netherlands and typically these breeding attempts fail.


Hatching is asynchronous but not completely, usually an average sized clutch takes only 2 to 3 days to hatch, although it may take up to 6 days to hatch a clutch of more than 4 eggs. Hatchlings start calling from within the shell as much as 38 hours before hatching, as a faint chep, chep, chack, peep, peep, peep may be heard. The young are covered with down and altricial (as are all raptors) at first but develop rapidly. Hatchlings measure about 13 cm (5.1 in) long at first and grow about 5 to 9 cm (2.0 to 3.5 in) in length each week until they fledge. The mothers typically brood the nestlings intensively for about two weeks, around the time grayer feathers start to develop through the nestlings’ down. The most key time for development may be at three weeks when the nestlings can stand a bit and start to develop their flight feathers. Also at the three-week stage, they can reach about half the adults’ weight and females start to noticeably outgrow the males. However, this growth requires increased food delivery so frequently results in lower nest attendance and, in turn, higher predation rates. Also rates of starvation at this stage can exceed 50% especially in the youngest of large clutches of 4 to 5. Nestlings at 4 weeks are starting to develop strong flight feathers, which they frequently flap; also they can start to pull on food but are still mainly fed by female and begin to make a whistling scream when she goes to fetch food from the male. More active feeding behavior by nestlings may increase their aggression towards each other. By the 5th week, they've developed many typical goshawk behaviors, sometimes mantling over food, testing balance by extending one leg and one wing at edge of nest (called "warbling" by falconers) and can wag their tails vigorously. Starvation risk also increases at this point due to their growing demands and, due to their incessant begging calls, vocal activity may court predators. In 6th week, they become "branchers", although still spend much of the time by the nest, especially by the edge. The young goshawks "play" by seizing and striking violent at a perch or by yanking off leaves and tossing them over their back. Wing feathers do not develop highly dimorphically, but male branchers are better developed than females who have more growing to do and can leave the nest up to 1–3 days sooner. The young rarely return to the nest after being 35 to 46 days of age and start their first flight another 10 days later, thus becoming full fledglings. Goshawk nestlings frequently engage in “runting”, wherein the older siblings push aside and call more loudly and are thus are feed more often at food deliveries, until the younger siblings may either starve to death, be trampled or killed by their siblings (referred to as siblicide or “cainism”). There is some evidence that mother goshawks may lessen the effects of runting by delaying incubation until their last eggs are laid. Food supply may be linked to higher rates of siblicides and, in many locations with consistent prey levels, runting and siblicide can occur somewhat seldom (meaning the northern goshawk is a “facultative” rather than “obligate cainist”). Nonetheless, either by predation, starvation or siblicide, few nests produce more than 2 to 3 fledglings. One pair in North America was able to successfully fledge all four of its young. Somewhat larger numbers of female fledglings are produced in Europe with their larger size, but the opposite is true in North America where sexual dimorphism is less pronounced. When food supplies are very high, though, European goshawks actually can produce somewhat more males than females.
At about 50 days old, the young goshawks may start hunting on their own but more often eat carrion either provided by parents or biologists. Most fledglings stay within 300 m (980 ft) of the nest at 65 days of age but can wander up to 1,000 km (620 mi) before dispersal at between 65 and 80 days old in sync with the full development of their flight feathers. Between 65 and 90 days after hatching, more or less all young goshawks become independent. There is no evidence that parents aggressively displace the young in the fall (as other raptorial birds have sometimes been reported to do), therefore the young birds seek independence on their own. Goshawk siblings are not cohesive together past 65 days, except for some lingering young females, whereas common buzzard broods are not recorded at their nests after 65 days but remain strongly cohesive with each other. 5% of radio-tagged young in Gotland, Sweden (entirely males) were found to disperse to another breeding area and join a different brood as soon as their flight feathers were developed enough. These seem to be cases of moving to a better food area. Parents and adoptive young seem to tolerate this, although parents do not seem to be able to tell the difference between their own and other young. It is only after dispersal that goshawks typically start to hunt and seem to drink more often than older birds, sometimes spend up to an hour bathing.


Nest success averages between 80 and 95% in terms of the number of nests that produce fledglings, with an average number of 2 to 3 fledglings per nest. About equal numbers of eggs and nestlings may be lost (6% lost in each the incubation and brooding periods per a study from Arizona) but according to a study from Spain large clutches of 4 to 5 had higher losses overall than medium-sized clutches of 2 to nearly 4. Total losses averaged 36% in Spain across clutches of 2–5. Similar results were found in Germany, with similar numbers of fledglings produced in very large clutches (more than 4) as in medium-sized ones (2–4). A grading of success from a study in Sweden found categories of competent and less competent pairs, with losses averaging 7% and 17% in these two groups, respectively. Studies from Finland and the Yukon Territory found that average number of fledglings varied dramatically based on food supply based on the cyclical nature of most prey in these northern areas, varying from average success rates of 0 to 3.9 fledglings in the latter region. Similar wide variations in breeding success in correlation to prey levels were noted at other areas, including Nevada (where the number of fledglings could be up to seven times higher when lagomorphs were at their population peaks) and Wisconsin.


Poor weather, which consists of cold springs that bear late cold spells, snow, and freezing rain, causes many nests to fail, and may also hamper courtship and lower brood size and overall breeding attempts. However, the most important cause of nest failure was found to be nest destruction by humans and other predations, starvation, then bad weather and collapse of nests in declining order. On average, humans are responsible based on known studies for about 17% of nest failures in Europe. 32% of 97 nestlings in Bavaria, Germany died because of human activities, while 59% of 111 broods in England failed due to this factor. Low food supplies are linked to predation, as it seems to cause greater risk of predation due to the lower nest attendance. Lower densities of pairs may actually increase nesting success, as per studies from Finland where the highest median clutch size, at 3.8, was in the area with the lowest densities. Similarly, in Schleswig-Holstein, nest failure was 14% higher where active nests were closer than 2 km (1.2 mi) apart compared to nests farther than this. Age may also play a factor in nest success, pairings where one mate is not fully mature (usually the female, as males rarely breed before attaining adult plumage) is less than half as successful as ones where both were mature, based on studies from Arizona. Overall, males do not normally breed at any younger than 3 years of age (although they are in adult plumage by two years) and females can breed at as young as 1 to 2 years old, but rarely produce successful, viable clutches. The age at sexual maturity is the same as other northern Accipiters as well as most buteonine hawks (eagles, on the other hand, can take twice as long to attain full sexual maturity). 6–9 years of age seem to be the overall peak reproductive years for most northern goshawks. However, some females can reproduce at as old as 17 years old and senescence is ambiguous in both sexes (possibly not occurring in males). Median values of brood success was found to be 77% in Europe and 82% in North America overall. Conversely, the median brood size is about half a chick smaller in North America than in Europe. In Europe, clutch size overall averages 3.3, the number of nestlings averages 2.5 and fledglings averages 1.9.


The lifespan in the wild is variable. It is known that in captivity, northern goshawks may live up to 27 years of age. Wild birds that survive their first two years can expect a lifespan of up to 11 years. There is one record (apparently sourced to the AOU) of a 16-year, 4-month-old goshawk. In Fennoscandia, starvation was found to account for 3-6% of reported deaths. In Norway, 9% of deaths were from starvation, but the percentage of demises from this increased to the north and affected juveniles more so than adults. In Gotland, Sweden, 28% of mortality was from starvation and disease. Both bacterial and viral diseases have been known to cause mortality in wild northern goshawks. Variable numbers of goshawks are killed by flying into man-made objects such as power lines and buildings and by automobiles, although lesser numbers are affected by powerline collisions than larger types of raptor.


The breeding range of the northern goshawk extends over one-third of North America and Asia each and perhaps five-sixths of Europe, a total area of over 30,000,000 km² (12,000,000 sq mi). Densities in western and central Europe were recorded at 3–5 pairs per 100 km² (39 sq mi). In boreal Sweden, numbers vary from 1 to 4.5 pairs per 100 km² (39 sq mi), while in similar habitat in Alaska there were 0.3 to 2.7/100 km² (39 sq mi). An average of only 1 pair per 100 km² (39 sq mi) would give world population of 600,000 breeding birds, likely at least half as many immature and other non-breeders. Recent study found 145,000–160,000 in Europe or 1 pair/60 km² (23 sq mi) to 1 pair/54 km² (21 sq mi). The total population of northern goshawks in the world probably ranges well over a million. The total European populations, estimated at as many as 160,000 pairs, makes it the fourth most numerous raptor in the continent, after the common buzzards (>700,000 pairs), Eurasian sparrowhawk (>340,000 pairs) and common kestrel (>330,000 pairs). The most populated countries by goshawks in Europe were Sweden (an estimated 10,000 pairs), Germany (8,500 pairs), Finland (6,000 pairs) and France (5,600 pairs). The highest densities of breeding pairs per 100 km² (39 sq mi) of land were in The Netherlands, Latvia and Switzerland, although this is biased due to the small land area of these countries. Russia has a roughly estimated 85,000 pairs of northern goshawk. In North America, there are a broadly estimated 150,000–300,000 individuals. In North America, most western populations at mid-latitudes have approximately 3.6–10.7 pairs100 km² (39 sq mi). A total of 107 nesting territories (1991–1996) were located on a 1,754 km² (677 sq mi) study area on the Kaibab Plateau, AZ, resulting in a density of 8.4 pairs/100 km² (39 sq mi). The estimated density in Pennsylvania (1.17 pairs/100 km² (39 sq mi)) suggests that eastern populations may occur at lower densities than western populations, but densities of eastern populations may increase as these populations recover. Typically, populations at far northern latitudes may occur at lower densities than those of southwestern and western populations in North America. Although median densities was similar, populations are overall much denser in Europe than in North America. The hotspots of density for goshawks in Europe lie in east-central Europe (around Poland) and in west-central area (the Netherlands/West Germany). Per the IUCN, the global population is estimated to consist of 1 million to nearly 2.5 million birds, making this one of the most numerous species in its diverse family (the red-tailed hawk and black kite both may have a similar global population size, whereas the Eurasian sparrowhawk and common buzzard are possibly slightly more numerous than goshawks despite their smaller ranges).
Mortality rates for first-year goshawks is often considerably higher than older birds. In studies from Gotland, Sweden, Schleswig-Holstein, Germany and the Netherlands, 40–42% of first-years died. By the second year, mortality rates drop to 31–35%, based on ring studies from the Netherlands and Finland. Based on studies from Gotland, Finland and the southwestern United States, annual mortality for adults is 15–21%, however, feather results indicate that annual mortality for adult goshawks is up to 7% higher in Europe than in North America. In many parts of the range, especially Europe, historic populations decreased regionally due to human persecution (especially shooting), disturbance and epidemic loss of habitat, especially during the 19th century and early 20th. Some states, like Pennsylvania, paid $5 bounties on Goshawks in the 1930s. From 1880 to 1930, an estimated 3,000–5,500 goshawk were being killed annually in Norway when bounties were offered. Shooting rate lowered later, causing the average number of goshawks shot to drop to 654 to for the period 1965–1970. Northern goshawks continue to be persecuted in Norway, shown by the high turnover rate of breeding females in Telemark County, revealed by DNA analysis of moulted feathers.   In Finland, where the species was not legally protected, 4,000–8,000 goshawks were being killed annually from 1964 to 1975. Most goshawks shot are incautious juveniles, with 58% of juvenile mortality in Germany and 59% from the Netherlands being killings by humans. Increase of pheasant releases in Vendsyssel, Denmark from 6,000 to 35,000 since 1994 has resulted in fewer goshawks as they often hunt the pheasants in winter and are shot, legally, by the region's gamekeepers. As recently as about 5 years before that, intentional killing by humans continued as the main cause of mortality for goshawks on Gotland, Sweden, causing 36% of deaths. In the United Kingdom and Ireland, the northern goshawk was extirpated in the 19th century because of specimen collectors and persecution by gamekeepers, but in recent years it has come back by immigration from Europe, escaped falconry birds, and deliberate releases. The goshawk is now found in considerable numbers in Kielder Forest, Northumberland, which is the largest forest in Britain. Overall there are some 620 pairs in Britain.
In the 1950s–1960s declines were increasingly linked with pesticide pollution. However, in early 1970s pesticide levels in the United States for goshawks were low. Eggshell thinning has not been a problem for most populations, although California eggshells (weight and thickness index) pre-1947 (pre-DDT) to 1947—1964 (DDT in use) declined some 8-12%. In Illinois, migratory goshawks during the winter of 1972-1973 invasion year contained less organochlorine and PCB residues than did other raptors, however, these birds were probably from nonagricultural, northern forests. Higher DDT levels seemed to have persisted quite recently in Europe. This was the case in Germany, especially in former East Germany where DDT was widely available until 1988, having been largely discontinued elsewhere after the 1970s. Goshawks, which had increased in The Netherlands after World War II due to less persecution, new woodlands and increased pigeon numbers, were found to have suddenly crashed from the late 1950s on. It was later revealed that this was due to DDT, the number of breeding pairs decreasing 84% from 1958 to 1963. As opposed to DDT, the main contaminant found to have reduced goshawks in Scandinavia during the 20th century were methyl mercury seed dressings used to reduce fungal attack in livestock.
Seemingly the remaining persistent conservation threat to goshawks, given their seeming overall resilience (at the species level) to both persecution and pesticides, is deforestation. Timber harvests are known to destroy many nests and adversely regional populations. Harvest methods that create extensive areas of reduced forest canopy cover, dropping to cover less than 35-40%, may be especially detrimental as cases of this usually cause all goshawks to disappear from the area. However, the mortality rates due to foresting practices are unknown and it is possible that some mature goshawks may simply be able to shift to other regions when a habitat becomes unsuitable but this is presumably unsustainable in the long-term. In harvest forests of California, where overstory trees are frequently removed, goshawks have been found to successfully remain as breeding species as long as some mature stands are left intact. Despite the decline of habitat quality and the frequent disturbances, this region's goshawks breeding success rates somewhat improbably did not reduce. Similarly, a study from Italy and France shows that goshawks only left woodlots when the canopy was reduced by more than 30%, although the European goshawk populations have long been known to be adaptable to some degree of habitat fragmentation.  Based on habitat usage studied in New Jersey and New York, this adaptability is not seen everywhere, as here nests were further from human habitation than expected on the basis of available habitat, an observation suggesting that disturbance regionally can reduce habitat quality. Similarly, studies from the American southwest and Canada have indicated that heavily logged areas caused strong long-term regional declines for goshawks. In Arizona, it was found that even when the nests were left intact, the noisy timber harvest work often caused failure of nesting during the incubation stage, and all nesting attempts that were occurring within 50 to 100 m (160 to 330 ft) of active logging failed, frequently after parents abandoned the nest. Other noisy activity, such as camping, have also caused nests to failure. Wildlife researchers and biologists do not seem to negatively affect goshawk nests, as they aware to keep forays to the nest brief and capture of adult goshawks for radio-tagging was found to not harm their success at raising broods.
In North America, several non-governmental conservation organizations petitioned the Department of Interior, United States Fish & Wildlife Service (1991 & 1997) to list the goshawk as "threatened" or "endangered" under the authority of the Endangered Species Act. Both petitions argued for listing primarily on the basis of historic and ongoing nesting habitat loss, specifically the loss of old-growth and mature forest stands throughout the goshawk's known range. In both instances, the U.S. Fish & Wildlife Service concluded that listing was not warranted, but state and federal natural resource agencies responded during the petition process with standardized and long-term goshawk inventory and monitoring efforts, especially throughout U.S. Forest Service lands in the Western U.S. The United States Forest Service (US Dept of Agriculture) has listed the goshawk as a "sensitive species", while it also benefits from various protection at the state level. In North America, the goshawk is federally protected under the Migratory Bird Treaty Act of 1918 by an amendment incorporating native birds of prey into the Act in 1972. The northern goshawk is also listed in Appendix II of the Convention on International Trade in Endangered Species (CITES).


The northern goshawk appears on the flag and coat of arms of the Azores. The archipelago of the Azores, Portugal, takes its name from the Portuguese language word for goshawk, (açor), because the explorers who discovered the archipelago thought the birds of prey they saw there were goshawks; later it was found that these birds were kites or common buzzards (Buteo buteo rothschildi). The goshawk features in Stirling Council's coat of arms via the crest of the Drummond Clan.
Hawks are highly associated with Guru Gobind Singh in the Sikh community. According to ornithologists, he is believed to have kept a white Northern Goshawk. This is reflected in that the Northern Goshawk was made the official state bird of Punjab, India.


The name "goshawk" is a traditional name from Anglo-Saxon gōshafoc, literally "goose hawk". The name implies prowess against larger quarry such as wild geese, but were also flown against crane species and other large waterbirds. The name "goose hawk" is somewhat of a misnomer, however, as the traditional quarry for goshawks in ancient and contemporary falconry has been rabbits, pheasants, partridge, and medium-sized waterfowl, which are similar to much of the prey the species hunts in the wild. A notable exception is in records of traditional Japanese falconry, where goshawks were used more regularly on goose and crane species. In ancient European falconry literature, goshawks were often referred to as a yeoman's bird or the "cook's bird" because of their utility as a hunting partner catching edible prey, as opposed to the peregrine falcon, also a prized falconry bird, but more associated with noblemen and less adapted to a variety of hunting techniques and prey types found in wooded areas. The northern goshawk has remained equal to the peregrine falcon in its stature and popularity in modern falconry.
Goshawk hunting flights in falconry typically begin from the falconer's gloved hand, where the fleeing bird or rabbit is pursued in a horizontal chase. The goshawk's flight in pursuit of prey is characterized by an intense burst of speed often followed by a binding maneuver, where the goshawk, if the prey is a bird, inverts and seizes the prey from below. The goshawk, like other accipiters, shows a marked willingness to follow prey into thick vegetation, even pursuing prey on foot through brush. Goshawks trained for falconry not infrequently escape their handlers and, extrapolated from the present day British population which is composed mostly of escaped birds as such, have reasonably high survival rates, although many do die shortly after escape and many do not successfully breed. The effect of modern-day collection of northern goshawks for falconry purposes is unclear, unlike some falcon species which can show regional declines due to heavy falconry collections but can increase in other areas due to established escapees from falconers.


The sharp-shinned hawk (Accipiter striatus) is a small hawk, with males being the smallest hawks in the United States and Canada, but with the species averaging larger than some Neotropical species, such as the tiny hawk. The taxonomy is far from resolved, with some authorities considering the southern taxa to represent three separate species: white-breasted hawk (A. chionogaster), plain-breasted hawk (A. ventralis), and rufous-thighed hawk (A. erythronemius). The American Ornithological Society keeps all four variations conspecific.


The sharp-shinned hawk is sometimes separated into four species, with the northern group (see distribution) retaining both the scientific name and the common name: sharp-shinned hawk (A. striatus). In addition to the nominate taxon (A. s. striatus), it includes subspecies perobscurus, velox, suttoni, madrensis, fringilloides, and venator. The three remaining taxa, each considered a monotypic species if split, are the white-breasted hawk (A. chionogaster; Kaup, 1852), plain-breasted hawk (A. ventralis; Sclater, 1866) and rufous-thighed hawk (A. erythronemius; Kaup, 1850). The breeding ranges of the groups are entirely allopatric, although the wintering range of the nominate group partially overlaps with the range of chionogaster (as is also the case with certain taxa within the nominate group). This allopatry combined with differences in plumage (see appearance) and, apparently, certain measurements, has been the background for the split, but hard scientific data are presently lacking (AOU). Disregarding field guides, most material published in recent years (e.g. AOU, Ferguson-Lees et al. p. 586, and Dickinson et al.) has therefore considered all to be members of a single widespread species – but not without equivocation: Ferguson-Lees et al. say that if they were to make a world list, they would include the three taxa as separate species (p. 75), and the AOU's comment includes the note "split almost certainly good".
Storer (1952) suggested that the southernmost populations within the nominate group were paler below, thus approaching chionogaster. This has also been reflected in recent guides, where A. s. madrensis of southern Mexico is described as being relatively pale below (compared to more northern subspecies), but if this is a sign of intergradation with chionogaster or a north-south cline which includes both the members of the nominate group and chionogaster remains unclear. In Bolivia, ventralis and  erythronemius approach each other, but no evidence of intergradation is known – something that, without actual specimens, also would be hard to prove due to the variability in the plumage of ventralis.


This species is widespread in North America, Central America, South America and the Greater Antilles. Below, the distributions of the four groups (see taxonomy) are described as they occur roughly from north to south:
The nominate (A. s. striatus) group is widespread in North America, occurring in all of the forested part of USA and Canada, breeding in most of it. Populations in the northern part of the range migrate south and spend the non-breeding season (winter) in the southern USA, Mexico and Central America as far south as Panama, with a smaller number spending the winter in the Greater Antilles. Resident populations exist in temperate parts of the US, Canada (in a few coastal regions), Mexico (highlands from Sonora to Oaxaca), Cuba, Hispaniola and Puerto Rico.
A. (s.) chionogaster (white-breasted hawk) occurs in highlands from far southern Mexico (Chiapas and Oaxaca), through Honduras, Guatemala and El Salvador, to Nicaragua. It is, as far as known, resident, but some local movements may occur.
A. (s.) ventralis (plain-breasted hawk) occurs in the coastal mountains of northern Venezuela and Colombia, south through the Andes from western Venezuela, through Colombia, Ecuador and Peru, to central Bolivia. A disjunct population occurs in the Tepuis of southern Venezuela (likely to extend into adjacent parts of Roraima in far northern Brazil, but this remains unconfirmed). It is, as far as known, resident, but some local movements may occur.
A. (s.) erythronemius (rufous-thighed hawk) is widespread in eastern South America in eastern and southern Brazil, Uruguay, Paraguay, north-eastern Argentina and south-eastern Bolivia. It is, as far as known, resident in some regions and migratory in others. The movements are generally poorly understood, but it only occurs seasonally at some localities in Argentina.


These birds surprise and capture most of their prey from cover or while flying quickly through dense vegetation. They are adept at navigating dense thickets, although this hunting method is often hazardous to the hawk. The great majority of this hawk's prey are small birds, especially various songbirds such as sparrows, wood-warblers, finches, wrens, nuthatches, tits, icterids and thrushes. Birds caught range in size from a 4.4 g (0.16 oz) Anna's hummingbird to a 577 g (1.272 lb) ruffed grouse and virtually any bird within this size range is potential prey. Typically, males will target smaller birds, such as sparrows and wood-warblers, and females will pursue larger prey, such as American robins and flickers, leading to a lack of conflict between the sexes for prey. These hawks often exploit backyard bird feeders in order to target congregations of ideal prey. They often pluck the feathers off their prey on a post or other perch. Rarely, sharp-shinned hawks will also eat rodents, lizards, frogs, snakes, and large insects, the latter typically being dragonflies captured on the wing during the hawk's migration. Bats have occasionally been recorded as a prey of this hawk.


Sharp-shinned hawks construct a stick nest in a large conifer or dense group of deciduous trees. Clutches of 3 to 8 eggs have been recorded, but 4 to 5 eggs is the typical clutch size. The eggs measure 37.6 mm × 30 mm (1.48 in × 1.18 in) and weigh about 19 g (0.67 oz). The eggs are prized by egg-collectors, because they are heavily marked with surprisingly colorful and varied markings. The incubation period is thought to average at about 30 days. After hatching, the young are brooded for 16 to 23 days by the female, while the male defends the territory and catches prey. The young fledge at the age of about a month and rely on their parents for feeding and protection another four weeks. The nesting sites and breeding behavior of sharp-shinned hawks are generally secretive, in order to avoid the predation of larger raptors, such as the northern goshawk and the Cooper's hawk. While in migration, adults are sometimes preyed on by most of the bird-hunting, larger raptors, especially the peregrine falcon. The breeding behavior of the taxa chionogaster (white-breasted hawk), ventralis (plain-breasted hawk) and erythronemius (rufous-thighed hawk) are comparably poorly known, but based on the available knowledge they appear to differ little from that of the nominate group


In North America this species declined in numbers in the 1960s and 1970s, probably as a result of the use of DDT and other pesticides. The population of USA and Canada has rebounded since and might even exceed historical numbers today, probably due to the combination of the ban on DDT and the proliferation of backyard bird feeders in North America which create unnaturally reliable and easy prey sources. Migratory sharp-shinned hawks are one of the most numerous raptors recorded at "hawk watches" across the country. An exception is the subspecies from Puerto Rico, Accipiter striatus venator, which is rare and listed as endangered by the U.S. Fish & Wildlife Service. The remaining resident subspecies from the Greater Antilles, fringilliodes from Cuba and nominate (A. s. striatus) from Hispaniola, are uncommon, local, and, at least in the case of the latter, decreasing. Both ventralis (plain-breasted hawk) and erythronemius (rufous-thighed hawk) are fairly common (but easily overlooked due to their secretive behavior) and presently considered safe. The situation for chionogaster (white-breasted hawk) is potentially more problematic due to its limited range, although it, at least locally, remains fairly common.


Acer campestre, known as the field maple, is a flowering plant species in the family Sapindaceae. It is native to much of continental Europe, Britain, southwest Asia from Turkey to the Caucasus, and north Africa in the Atlas Mountains. It has been widely planted, and is introduced outside its native range in Europe and areas of USA and Western Australia with suitable climate.


It is a deciduous tree reaching 15–25 m (49–82 ft) tall, with a trunk up to 1 m (3 ft 3 in) in diameter, with finely fissured, often somewhat corky bark. The shoots are brown, with dark brown winter buds. The leaves are in opposite pairs, 5–16 cm (2.0–6.3 in) long (including the 3–9 cm (1.2–3.5 in) petiole) and 5–10 cm (2.0–3.9 in) broad, with five blunt, rounded lobes with a smooth margin. Usually monoecious, the flowers are produced in spring at the same time as the leaves open, yellow-green, in erect clusters 4–6 cm (1.6–2.4 in) across, and are insect-pollinated. The fruit is a samara with two winged achenes aligned at 180°, each achene is 8–10 mm (0.31–0.39 in) wide, flat, with a 2 cm (0.79 in) wing.
The two varieties, not accepted as distinct by all authorities, are:
Acer campestre var. campestre - downy fruit
Acer campestre var. leiocarpum (Opiz) Wallr. (syn. A. campestre subsp. leiocarpum) - hairless fruit
The closely related Acer miyabei replaces it in eastern Asia.


The native range of field maple includes much of Europe, including Denmark, Poland and Belarus, England north to southern Scotland (where it is the only native maple), southwest Asia from Turkey to the Caucasus, and north Africa in the Atlas Mountains. In many areas, the original native range is obscured by widespread planting and introductions. In North America it is known as hedge maple and in Australia, it is sometimes called common maple. In Nottinghamshire, England it was known locally as dog oak.


Field maple is an intermediate species in the ecological succession of disturbed areas; it typically is not among the first trees to colonise a freshly disturbed area, but instead seeds in under the existing vegetation. It is very shade-tolerant during the initial stages of its life, but it has higher light requirements during its seed-bearing years. It exhibits rapid growth initially, but is eventually overtaken and replaced by other trees as the forest matures. It is most commonly found on neutral to alkaline soils, but more rarely on acidic soil.
Diseases include a leaf spot fungus Didymosporina aceris, a mildew Uncinula bicornis, a canker Nectria galligena, and verticillium wilt Verticillium alboatrum. The leaves are also sometimes damaged by gall mites in the genus Aceria, and the aphid Periphyllus villosus.


The field maple is widely grown as an ornamental tree in parks and large gardens. The wood is white, hard and strong, and used for furniture, flooring, wood turning and musical instruments, though the small size of the tree and its relatively slow growth make it an unimportant wood. It has an OPALS rating of 7.
It is locally naturalised in parts of the United States and more rarely in New Zealand.
The hybrid maple Acer × zoeschense has A. campestre as one of its parents.
The tree has gained the Royal Horticultural Society's Award of Garden Merit.


Over 30 cultivars of Acer campestre are known, selected for their foliage or habit, or occasionally both; several have been lost to cultivation.
'Carnival'
'Commodore'
'Compactum'
'Eastleigh Weeping'
'Elegant'
'Elsrijk'
'Evenly Red'
'Fastigiatum'
'Green Weeping'
'Leprechaun'
'Lienco'
'Marjolein'
'Nanum'
'Pendulum'
'Postelense'
'Pulverulentum'
'Punctatissimum'
'Puncticulatum'
'Queen Elisabeth'
'Red Shine'
'Royal Ruby'
'Ruby Glow'
'Schwerinii'
'Senator'
'Silver Celebration'
'Silver Dawn'
'Streetwise'
'Tauricum'
'Tomentosum'
'William Caldwell'
'Zorgvlied'


Acer campestre (and the similar A. monspessulanum) are popular among bonsai enthusiasts. The dwarf cultivar 'Microphyllum' is especially useful in this regard. A. campestre bonsai have an appearance distinct from those selected from some other maples such as A. palmatum with more frilly, translucent, leaves. The shrubby habit and smallish leaves of A. campestre respond well to techniques encouraging ramification and leaf reduction.


Acer circinatum, the vine maple, is a species of maple native to western North America.


It most commonly grows as a large shrub growing to around 5 to 8 metres (16 to 26 feet) tall, but it will occasionally form a small to medium-sized tree, exceptionally to 18 m (59 ft) tall. The shoots are slender and hairless. The trunk rarely grows more than 25 centimetres (10 inches) thick.
The leaves are 3 to 14 cm (1+1⁄4 to 5+1⁄2 in) long and broad, opposite, palmately lobed with 7 to 11 lobes, almost circular in outline, and thinly hairy on the underside; the lobes are pointed and with coarsely toothed margins. The leaves turn bright yellow to orange-red in autumn. The flowers are small, 6 to 9 millimetres (1⁄4 to 3⁄8 in) in diameter, with a dark red calyx and five short greenish-yellow petals; they are produced in open corymbs of 4 to 20 together in spring. The fruit is a two-seeded samara, each seed 8 to 10 mm (5⁄16 to 3⁄8 in) in diameter, with a lateral wing 2 to 4 cm (3⁄4 to 1+5⁄8 in) long.
Vine maple trees can bend over easily. Sometimes, this can cause the top of the tree to grow into the ground and send out a new root system, creating a natural arch. This characteristic makes it the only maple capable of layering.


It belongs to the Palmatum group of maple trees native to East Asia with its closest relatives being the Acer japonicum (fullmoon maple) and Acer pseudosieboldianum (Korean maple). It can be difficult to distinguish from these species in cultivation. It is the only member of the Palmatum group that resides outside of Asia.


It can be found from southwest British Columbia to northern California, usually within 300 kilometres (190 miles) of the Pacific Ocean coast, found along the Columbia Gorge and Coastal Forest. It can found no further inland than the east side of the Cascade Range. It typically grows in the understory below much taller forest trees, but can sometimes be found in open ground, and occurs at altitudes from sea level up to 1,500 m (4,900 ft).


It is occasionally cultivated outside its native range as an ornamental tree, from Juneau, Alaska, and Ottawa, Ontario, to Huntsville, Alabama, and also in northwestern Europe.


The Quinault people used the shoots to weave baskets.


It is a medium-sized to large deciduous tree, growing to 15–25 m tall—exceptionally to 38 m—with an elliptical crown of moderate density with a smooth or rounded outline. The bark is a light gray with thick irregular curling ridges; as the tree matures, the bark tends to become plated. The twigs are slender, somewhat shiny, reddish brown. The terminal buds are sharply pointed, brown and pubescent. The leaves are opposite, simple, palmately lobed and veined, 3–9.5 cm long and 3.5–11 cm broad, with an entire margin and three or five somewhat rounded lobes, and a 2–8 cm long petiole. They are green above and paler and pubescent below. In fall they turn orange and yellow. The flowers are regular, pentamerous, and appear on yellow-green corymbs and are quite small. They hang from puberulent pedicels 2.4–5 cm long in clusters of a few flowers, appearing before or with the leaves in early spring. This is about two weeks prior to the maturation of the flowers of Acer saccharum. The tree is generally diecious, though they are often also polygamous, that is having bisexual and unisexual flowers on the same individual. The fruit is a paired samara 1.5–3 cm long.
Acer floridanum can easily be confused in the field with the closely related Acer leucoderme and Acer saccharum. It can be best distinguished from A. saccharum by noting the smaller leaves with short and acute lobes, the smaller samaras, and the more whitish bark. Several overlaps in genetics between these two species have been found in east Texas and in the zone from Maryland south to northern Florida, despite the fact that Maryland is listed as beyond the natural range of the tree. In light of this information, it can be assumed that the two hybridize. From A. leucoderme, it is best told by the white hairs on the undersides of the leaves, yellow-haired in A. leucoderme.


Debate still exists about its taxonomic status, which has been controversial for at least 100 years.
The Florida Maple was first recognised as distinct in 1860 by Alvan Wentworth Chapman, who treated it as a variety of A. saccharum. In 1886 Ferdinand Albin Pax decided it was distinct enough to be treated as a separate species, making the new combination A. floridanum (Chapm.) Pax. In 1952, Yves Desmarais took an intermediate option, treating it as a subspecies Acer saccharum subsp. floridanum (Chapm.) Desmarais, a treatment which has fairly wide recent recognition.
A further problem exists with the specific name Acer barbatum, given to a maple by André Michaux in 1803 from samples collected in the Carolinas during his decade in North America from 1785 to 1796. For a long time it was unclear if the plant he collected was Acer saccharum (Sugar Maple) or A. floridanum, as his samples were badly damaged on his return to Paris. M. L. Fernald reexamined the species in the mid-1940s for the 8th edition of Gray's Manual, published in 1950; on reviewing Michaux's notes on A. barbatum, he decided to apply this name to the Florida Maple in 1945, based on his interpretation that Michaux's samples, which he only knew through notes (Michaux's collections were in Paris, inaccessible as World War II had not yet ended), corresponded more closely to Florida Maple than to Sugar Maple. Since the oldest given name takes precedence, he used the name A. barbatum for the Florida Maple. Many subsequent authors accepted this judgement, such as the United States Forest Service, and Wilbur H. Duncan and Marion Duncan's Trees of the Southeastern United States, published in 1988. However, recent examination by D. B. Ward has shown that they are typical Acer saccharum after all, and not A. floridanum as Fernald had thought without examination, and thus Michaux's name is correctly a synonym of A. saccharum.


The distribution is discontinuous in the Piedmont and Atlantic Coastal Plain from southeastern Virginia southwest across North Carolina, South Carolina and Georgia, as well as into the Florida Panhandle. The range goes farther west across Alabama, Mississippi, Louisiana, into eastern Texas, and north through Arkansas and into eastern Oklahoma. The species also occurs in several isolated locations roughly halfway down the Gulf Coast of the Florida peninsula, and also in at least one location in central Oklahoma. The species is also found in isolated locations of Illinois, Missouri, Tennessee and Kentucky.
The average annual rainfall within the native area ranges from 112 to 163 cm (44 to 64 in). The driest months average no less than 50 mm (2.0 in). The normal temperatures in January within the range vary from 11 to 18 °C (52 to 64 °F) maximum, and from −2 to 7 °C (28 to 45 °F) minimum, whereas in July normal maxima are 29 to 33 °C (84 to 91 °F), and minima are 21 to 24 °C (70 to 75 °F). The tree favours moist, but well-drained fertile soils, especially on stream terrace, in coves, and on adjacent bluffs and ridgetops. It grows best on soils containing calcareous material such as limestone or marl. It also grows well on the densely forested hammocks of Florida, hence its alternative common name hammock maple. It is most often confined to the understory.


While not an overwhelmingly popular tree in cultivation, it is sometimes employed in the Southern United States as a shade tree due to its round crown and its greater resistance to heat than that of its more showy relative the sugar maple. Several species of birds and especially squirrels make use of the tree as a nesting site and also consume its seeds as a food source.
Despite the fact that of itself Florida Maple is not employed as a commercial timber species, it is used with associated commercial species when the products are pulpwood, sawtimber, or wood veneer stock. It is considered a hard maple and as high quality individuals are suitable for producing furniture, flooring, paneling, and shoe lasts. However, its relative scarcity, small size, and fairly poor shape generally confine its use to only factory and box lumber, and even this is only an occasional occurrence. It has, however, been experiencing growing popularity as an ornamental or shade tree, especially in the southern United States due to its high heat resistance. It is also a source of maple syrup, though again its size and rarity limit its use in this regard, especially in light of the Sugar Maple's established popularity within the business.


Acer ginnala, the Amur maple, is a  plant species with woody stems native to northeastern Asia from easternmost Mongolia east to Korea and Japan, and north to the Russian Far East in the Amur River valley. It is a small maple with deciduous leaves that is sometimes grown as a garden subject or boulevard tree.


Acer ginnala is a deciduous spreading shrub or small tree growing to 3–10 m (9.8–32.8 ft) tall, with a short trunk up to 20–40 cm (8–16 in) diameter and slender branches. The bark is thin, dull gray-brown, and smooth at first but becoming shallowly fissured on old plants. The leaves are opposite and simple, 4–10 cm (1+1⁄2–4 in) long and 3–6 cm (1+1⁄4–2+1⁄4 in) wide, deeply palmately lobed with three or five lobes, of which two small basal lobes (sometimes absent) and three larger apical lobes; the lobes are coarsely and irregularly toothed, and the upper leaf surface glossy. The leaves turn brilliant orange to red in autumn, and are on slender, often pink-tinged, petioles 3–5 cm (1+1⁄4–2 in) long. The flowers are yellow-green, 5–8 mm (0.20–0.31 in) diameter, produced in spreading panicles in spring as the leaves open. The fruit is a paired reddish samara, 8–10 mm (0.31–0.39 in) long with a 1.5–2 cm (5⁄8–3⁄4 in) wing, maturing in late summer to early autumn.


Amur maple is closely related to Acer tataricum (Tatar maple), and some botanists treat it as a subspecies  A. tataricum subsp. ginnala (Maxim.) Wesm. The glossy, deeply lobed leaves of A. ginnala distinguish it from A. tataricum, which has matte, unlobed or only shallowly lobed leaves.


Acer ginnala is grown as an ornamental plant in northern regions of Europe and North America. It is the most cold-tolerant maple, hardy to zone 2. It is naturalised in parts of North America. Planted on exceptional sites facing south west with consistent moisture and light loamy soils, this tree can grow 3 to 4 feet per year making it a fast grower.  It is often planted as a shrub along borders.
In the UK it has gained the Royal Horticultural Society's Award of Garden Merit.
It is also valued in Japan and elsewhere as a species suitable for bonsai.
It is a nonnative invasive species in parts of northern America.


Due to its vigor and fall colors of yellows and bright reds, the size being a small tree of 6 metres (20 feet) wide by 6 m tall on average, it suits many for smaller landscapes and for planting under power lines.  Cultivars have emerged for those wanting these attributes.
Flame (Fiery red autumn foliage, very strong vigor)


Acer glabrum is a small tree growing to 6–9 metres (20–30 feet) tall, exceptionally 12 m (39 ft), with a trunk around 13 centimetres (5 inches) in diameter, exceptionally around 25 cm (10 in). The leaves are 2–13 cm (3⁄4–5 in) broad, three-lobed (rarely five-lobed), variable in the depth of lobing, occasionally so deeply lobed as to be divided into three leaflets; the lobes have an acute apex and a coarsely serrated margin. The flowers are produced in corymbs of five to ten, yellowish-green, at the same time as the new leaves in spring. The fruit is a samara or winged seed, which develops in fused pairs at an angle of less than 45° when mature, though some varieties spread out to 90°.


There are four to six varieties, some of them treated by some authors at the higher rank of subspecies:
Acer glabrum var. glabrum (syn. subsp. glabrum; Rocky Mountain maple)– Rocky Mountains, Montana to New Mexico
Acer glabrum var. diffusum (Greene) Smiley (syn. subsp. diffusum (Greene) A.E.Murray; Rocky Mountain maple) – eastern California, Nevada, Utah
Acer glabrum var. douglasii (Hook.) Dippel (syn. subsp. douglasii (Hook.) Wesm.; Douglas maple) – Alaska south to Washington and Idaho
Acer glabrum var. greenei Keller (Greene's maple) – endemic-central California
Acer glabrum var. neomexicanum (Greene) Kearney & Peebles (syn. subsp. neomexicanum (Greene) A.E.Murray; New Mexico maple) – New Mexico
Acer glabrum var. torreyi (Greene) Smiley (syn. subsp. torreyi (Greene) A.E.Murray; Torrey maple) – endemic-Northern California


Acer glabrum is plentiful in many parts of the Rocky Mountains, often growing with ponderosa pine, Douglas-fir, and quaking aspen. It can be found in dry rocky areas.


It tends to be found in brush fields arising from fire-disturbed sites. Conifers tend to replace it in well-forested areas.  The foliage is browsed by game animals (especially deer and elk in winter), cattle, and sheep.


Native Americans utilized the strong stems for snowshoe frames, bows, and other applications. Some Plateau Indian tribes drink an infusion of Douglas maple as a treatment for diarrhea. Ramah Navajo use an infusion of the glabrum variety for swellings, and also as a "life medicine", or panacea.


Acer grandidentatum, commonly called bigtooth maple, is a species of maple native to interior western North America. It occurs in scattered populations from western Montana to central Texas in the United States and south to Coahuila in northern Mexico.


It is a small to medium-sized deciduous tree growing to 10–15 metres (33–49 feet) tall and a trunk of 20–35 centimetres (8–14 inches) diameter. The bark is dark brown to gray, with narrow fissures and flat ridges creating plate-like scales; it is thin and easily damaged. The leaves are opposite, simple, 6–12 cm (2+1⁄4–4+3⁄4 in) long and broad, with three to five deep, bluntly-pointed lobes, three of the lobes large and two small ones (not always present) at the leaf base; the three major lobes each have 3–5 small subsidiary lobules. The leaves turn golden yellow to red in autumn (less reliably in warmer areas).
The flowers appear with the leaves in mid spring; they are produced in corymbs of 5–15 together, each flower yellow-green, about 4–5 millimetres (3⁄16–3⁄16 in) diameter, with no petals. The fruit is a paired samara (two winged seeds joined at the base), green to reddish-pink in color, maturing brown in early fall; each seed is globose, 7–10 mm (1⁄4–3⁄8 in) diameter, with a single wing 2–3 cm (3⁄4–1+1⁄4 in) long.


It is closely related to Acer saccharum (sugar maple), and is treated as a subspecies of it by some botanists, as Acer saccharum subsp. grandidentatum (Nutt.) Desmarais.


It grows from the Rocky Mountains in southeast Idaho, through Utah and further south.
It commonly grows in limestone soils but can adapt to a wide range of well-drained soils, from sand to clays to even white limestone areas. It prefers sheltered canyons, valleys, and the banks of mountain streams, primarily at higher elevations but occasionally at lower elevations in disjunct locales such as the southern edge of the Edwards Plateau in Texas and in the Wichita Mountains of southwestern Oklahoma.


Although it is found in continental climate over all of its natural range, planted specimens grow well in the maritime climate of Vancouver. It is slow growing when young, and does not have many pests.
It is occasionally planted as an ornamental tree, valued for its drought tolerance and ability to grow in rocky landscapes.


The sweetish sap is used in western North America to make maple sugar.


Acer nigrum, the black maple, is a species of maple closely related to A. saccharum (sugar maple), and treated by some authors as a subspecies of it, as Acer saccharum subsp. nigrum.
Identification can be confusing due to the tendency of the two species to form hybrids. The simplest and most accurate method for distinguishing between the two trees is the generally three-lobed leaves of the black maple versus the generally five-lobed leaves of the sugar maple. The leaves of the black maple also tend to have a drooping appearance. Other differences that are not as pronounced include darker, more deeply grooved bark, slightly smaller seeds, a downy underside, and thicker petioles.  Hybrids are intermediate in their characteristics.


The geographic range of A. nigrum is slightly more limited than the sugar maple, encompassing much of the Midwestern United States, portions of the Eastern United States, and the  southeast of Canada in southern Ontario.


The black maple's mature height ranges from 21 to 34 meters (70 to 110 feet).


This species is used similarly to the A. saccharum, for timber as hard maple, for landscaping, and for maple syrup production.


Acer pseudoplatanus, known as the sycamore in the British Isles and as the sycamore maple in the United States,  is a species of flowering plant in the soapberry and lychee family Sapindaceae. It is a large deciduous, broad-leaved tree, tolerant of wind and coastal exposure. It is native to Central Europe and Western Asia, from France eastward to Ukraine, northern Turkey and the Caucasus and southward in the mountains of Italy and northern Iberia.
The sycamore establishes itself easily from seed and was introduced to the British Isles by 1500. It is now naturalised there and in other parts of Europe, North America, Australia and New Zealand, where it may become an invasive species.
The sycamore can grow to a height of about 35 m (115 ft) and the branches form a broad, rounded crown. The bark is grey, smooth when young and later flaking in irregular patches. The leaves grow on long leafstalks and are large and palmate, with five large radiating lobes. The flowers are greenish-yellow and hang in dangling flowerheads called panicles. They produce copious amounts of pollen and nectar that are attractive to insects. The winged seeds or samaras are borne in pairs and twirl to the ground when ripe. They germinate freely in the following spring.
In its native range, the sycamore is associated with a biodiverse range of invertebrates and fungi, but these are not always present in areas to which it has been introduced. It is sometimes planted in urban areas for its value as an amenity tree. It produces a hard-wearing, creamy-white close-grained timber that is used for making musical instruments, furniture, joinery, wood flooring and kitchen utensils. It also makes good firewood. The rising sap in spring has been used to extract sugar and make alcoholic and non-alcoholic drinks. Bees collecting the nectar make honey.


Acer pseudoplatanus was first described by the Swedish naturalist Carl Linnaeus in his Species Plantarum in 1753. It is the type species in the maple genus Acer. Many forms and varieties have been proposed, including natural varieties such as var. macrocarpum Spach, var. microcarpum Spach, and var. tomentosum Tausch, and forms such as f. erythrocarpum (Carrière) Pax, f. purpureum (Loudon) Rehder, and f. variegatum (Weston) Rehder. These are all now considered to be synonyms of Acer pseudoplatanus L.
The specific name pseudoplatanus refers to the superficial similarity of the leaves and bark of the sycamore to those of plane trees in the genus Platanus, the prefix pseudo- (from Ancient Greek) meaning "false". However, the two genera are in different families that are only distantly related. Acer and Platanus differ in the position in which leaves are attached to the stem (alternate in Platanus, paired or opposite in Acer) and in their fruit, which are spherical clusters in Platanus and paired samaras (winged fruit) in Acer.
The common name "sycamore" was originally applied to the fig species Ficus sycomorus, the sycamore or sycomore referred to in the Bible, that is native to southwest Asia. Other common names for the tree include false plane-tree, great maple, Scottish maple, mount maple, mock-plane, or Celtic maple.


Sycamore trees produce their flowers in hanging branched clusters known as panicles that contain a variety of different flower types. Most are morphologically bisexual, with both male and female organs, but function as if they were unisexual. Some are both morphologically and functionally male, others morphologically bisexual but function as males, and still others are morphologically bisexual but function as females. All of the flower types can produce pollen, but the pollen from functionally female flowers does not germinate. All flowers produce nectar, the functionally female flowers producing it in greater volume and with a higher sugar content.
Sycamore trees are very variable across their wide range and have strategies to prevent self-pollination, which is undesirable because it limits the genetic variation of the progeny and may depress their vigour. Most inflorescences are formed of a mixture of functionally male and functionally female flowers. On any one tree, one or other of these flower types opens first and the other type opens later. Some trees may be male-starters in one year and female-starters in another. The change from one sex to the other may take place on different dates in different parts of the crown, and different trees in any one population may come into bloom over the course of several weeks, so that cross-pollination is encouraged, although self-pollination may not be completely prevented.
The sycamore may hybridise with other species in Acer section Acer, including with A. heldreichii where their natural ranges overlap and with A.velutinum. Intersectional hybrids with A. griseum (Acer section Trifoliata) are also known, in which the basal lobes of the leaf are reduced in size, making the leaves appear almost three-lobed (trifoliate).


In its native range, the sycamore is a natural component of birch (Betula sp.), beech (Fagus sp.) and fir (Abies sp.) forests. It readily invades disturbed habitats such as forest plantations, abandoned farmland and brownfield land, railway lines and roadsides verges, hedgerows, native and semi-natural woodland. In New Zealand, it invades the high country tussock grassland.  As an introduced, invasive species, it may degrade the laurel forest in Madeira and Portugal and is a potential threat to the rare endemic Madeiran orchid, Dactylorhiza foliosa.
It is tolerant of a wide range of soil types and pH, except heavy clay, and is at its best on nutrient-rich, slightly calcareous soils. The roots of the sycamore form highly specific beneficial mycorrhizal associations with the fungus Glomus hoi, which promotes phosphorus uptake from the soil. Sycamore mycorrhizas are of the internal arbuscular mycorrhizal type, in which the fungus grows within the tissues of the root and forms branched, tree-like structures within the cells of the root cortex.
The larvae of a number of species of moth use the leaves as a food source. These include the sycamore moth (Acronicta aceris), the maple prominent (Ptilodon cucullina) and the plumed prominent (Ptilophora plumigera). The horse-chestnut leaf miner (Cameraria ohridella) occasionally lays its eggs on the sycamore, although 70% of the larvae do not survive beyond the second instar. The leaves attract aphids, and also the ladybirds and hoverflies that feed on them. The flowers produce copious amounts of nectar and pollen and are attractive to bees and other insects, and the seeds are eaten by small mammals such as voles and birds. As an introduced plant, in Britain the sycamore has a relatively small associated insect fauna of about 15 species, but it does have a larger range of leafhoppers than does the native field maple.
The tree may also be attacked by the horse chestnut scale insect (Pulvinaria regalis), which sucks sap from the trunk and branches, but does not cause serious damage to the tree. Sometimes squirrels will strip the bark off branches, girdling the stem; as a result whole branches may die, leaving brown, wilted leaves.
The sycamore gall mite Eriophyes macrorhynchus produces small red galls, similar to those of the nail gall mite Eriophyes tiliae, on leaves of sycamore and field maple, Acer campestris from April onwards. Another mite, Aceria pseudoplatani causes a 'sycamore felt gall' on the underside of leaves of both sycamore and Norway maple (Acer platanoides). The sycamore aphid Drepanosiphum platanoidis sucks sap from buds and foliage, producing large quantities of sticky honeydew that contaminate foliage, cars and garden furniture beneath.
The sycamore is susceptible to sooty bark disease, caused by the fungus Cryptostroma corticale. This causes wilting of the crown and the death of branches. Rectangular patches of bark become detached exposing thick layers of black fungal spores. The fungus may be present in the heartwood without symptoms for many years, working its way towards the bark following long, hot summers. The spores are hyper-allergenic and cause a condition called maple bark stripper’s disease, a hypersensitivity pneumonitis. Less serious is the fungus Rhytisma acerinum which often forms the disease known as tar spot, in which black spots with yellow margins form on the foliage. The leaves may fall prematurely but the vigour of the tree is little affected. Sycamore leaf spot, caused by the fungus Cristulariella depraedans, results in pale blotches on leaves which later dry up and fall. This disease can cause moderate leaf loss but trees are little affected in the long run.


Horses eating seeds or emergent seedlings of A. pseudoplatanus can suffer from an often fatal condition of atypical myopathy.


Sycamore is planted in parks for ornamental purposes, and sometimes as a street tree, for its tolerance of air pollution makes it suitable for use in urban plantings. Owing to its tolerance to wind, it has often been planted in coastal and exposed areas as a windbreak.
It produces a hard-wearing, white or cream close-grained timber that turns golden with age. The wood can be worked and sawn in any direction and is used for making musical instruments, furniture, joinery, wood flooring and parquetry. Because it is non-staining, is used for kitchen utensils, wooden spoons, bowls, rolling pins and chopping boards. In Scotland it has traditionally been used for making fine boxes, sometimes in association with contrasting, dark-coloured laburnum wood.
Occasionally, trees produce wood with a wavy grain, greatly increasing the value for decorative veneers. The wood is a medium weight for a hardwood, weighing 630 kg per cubic metre. It is a traditional wood for use in making the backs, necks and scrolls of violins. The wood is often marketed as rippled sycamore. Whistles can be made from straight twigs when the rising sap allows the bark to be separated, and these, and sycamore branches, are used in customs associated with early May in Cornwall. The wood is used for fuel, being easy to saw and to split with an axe, producing a hot flame and good embers when burnt.
In Scotland, sycamores were once a favoured tree for hangings, because their lower branches rarely broke under the strain. Both male and female flowers produce abundant nectar, which makes a fragrant, delicately flavoured and pale-coloured honey. The nectar and copious dull yellow ochre pollen are collected by honeybees as food sources. The sap rises vigorously in the spring and like that of sugar maple can be tapped to provide a refreshing drink, as a source of sugar and to make syrup or beer.


Under this sycamore tree at Tolpuddle in Dorset, England, six agricultural labourers, known as the Tolpuddle Martyrs, formed an early trades union in 1834. They were found to have breached the Unlawful Oaths Act 1797 and were transported to Australia. The subsequent public outcry led to their release and return. The tree now has a girth of 5.9 metres (19 feet, 4 inches) and a 2005 study dated the tree to 1680. The tree is cared for by the National Trust, which has pollarded the tree in 2002 and 2014.


Acer rubrum, the red maple, also known as swamp maple, water maple or soft maple, is one of the most common and widespread deciduous trees of eastern and central North America. The U.S. Forest service recognizes it as the most abundant native tree in eastern North America. The red maple ranges from southeastern Manitoba around the Lake of the Woods on the border with Ontario and Minnesota, east to Newfoundland, south to Florida, and southwest to East Texas. Many of its features, especially its leaves, are quite variable in form. At maturity, it often attains a height of around 30 m (100 ft). Its flowers, petioles, twigs and seeds are all red to varying degrees. Among these features, however, it is best known for its brilliant deep scarlet foliage in autumn.
Over most of its range, red maple is adaptable to a very wide range of site conditions, perhaps more so than any other tree in eastern North America. It can be found growing in swamps, on poor dry soils, and almost anywhere in between. It grows well from sea level to about 900 m (3,000 ft). Due to its attractive fall foliage and pleasing form, it is often used as a shade tree for landscapes. It is used commercially on a small scale for maple syrup production as well as for its medium to high quality lumber. It is also the state tree of Rhode Island. The red maple can be considered weedy or even invasive in young, highly disturbed forests, especially frequently logged forests. In a mature or old growth northern hardwood forest, red maple only has a sparse presence, while shade-tolerant trees such as sugar maples, beeches, and hemlocks thrive. By removing red maple from a young forest recovering from disturbance, the natural cycle of forest regeneration is altered, changing the diversity of the forest for centuries to come.


Though A. rubrum is sometimes easy to identify, it is highly changeable in morphological characteristics. It is a medium to large sized tree, reaching heights of 27 to 38 metres (90 to 120 ft) and exceptionally over 41 metres (135 feet) in the southern Appalachians where conditions favor its growth. The leaves are usually 9 to 11 centimetres (3+1⁄2 to 4+1⁄4 in) long on a full-grown tree. The trunk diameter often ranges from 46 to 88 cm (18 to 35 in); depending on the growing conditions, however, open grown trees can attain diameters of up to 153 centimetres (60 in). The trunk will remain free of branches until some distance up the tree on forest grown trees, while individuals grown in the open are shorter and thicker with a more rounded crown. Trees on poorer sites often become malformed and scraggly. Generally the crown is irregularly ovoid with ascending whip-like curved shoots. The bark is a pale grey and smooth when the individual is young. As the tree grows the bark becomes darker and cracks into slightly raised long plates. The largest known living red maple is located near Armada, Michigan, at a height of 38.1 m (125 ft) and a bole circumference, at breast height, of 4.95 m (16 ft 3 in).
The leaves of the red maple offer the easiest way to distinguish it from its relatives. As with all North American maple trees, they are deciduous and arranged oppositely on the twig. They are typically 5–10 cm (2–4 in) long and wide with 3-5 palmate lobes with a serrated margin. The sinuses are typically narrow, but the leaves can exhibit considerable variation. When five lobes are present, the three at the terminal end are larger than the other two near the base. In contrast, the leaves of the related silver maple, A. saccharinum, are much more deeply lobed, more sharply toothed and characteristically have 5 lobes. The upper side of A. rubrum's leaf is light green and the underside is whitish and can be either glaucous or hairy. The leaf stalks are usually red and are up to 10 cm (4 in) long. The leaves can turn a characteristic brilliant red in autumn, but can also become yellow or orange on some individuals. Soil acidity can influence the color of the foliage and trees with female flowers are more likely to produce orange coloration while male trees produce red. The fall colors of red maple are most spectacular in the northern part of its range where climates are cooler.
The twigs of the red maple are reddish in color and somewhat shiny with small lenticels. Dwarf shoots are present on many branches. The buds are usually blunt and greenish to reddish in color, generally with several loose scales. The lateral buds are slightly stalked, and in addition there may be collateral buds present as well. The buds form in fall and winter and are often visible from a distance due to their large size and reddish tint. The leaf scars on the twig are V-shaped and contain 3 bundle scars.
The flowers are generally unisexual, with male and female flowers appearing in separate sessile clusters, though they are sometimes also bisexual. They appear in late winter to early spring, from December to May depending on elevation and latitude, usually before the leaves. The tree itself is considered polygamodioecious, meaning some individuals are male, some female, and some monoecious. Under the proper conditions, the tree can sometimes switch from male to female, male to hermaphroditic, and hermaphroditic to female. The red maple will begin blooming when it is about 8 years old, but it significantly varies between tree to tree: some trees may begin flowering when they are 4 years old. The flowers are red with 5 small petals and a 5-lobed calyx, usually at the twig tips. The staminate flowers are sessile. The pistillate flowers are borne on pedicels that grow out while the flowers are blooming, so that eventually the flowers are in a hanging cluster with stems 1 to 5 cm (1⁄2 to 2 in) long. The petals are lineal to oblong in shape and are pubescent. The pistillate flowers have one pistil formed from two fused carpels with a glabrous superior ovary and two long styles that protrude beyond the perianth. The staminate flowers contain between 4 and 12 stamens, often with 8.
The fruit is a samara 15 to 25 millimeters (5⁄8 to 1 in) long that grows in pairs with somewhat divergent wings at an angle of 50 to 60 degrees. They are borne on long slender stems and are variable in color from light brown to reddish. They ripen from April through early June, before even the leaf development is altogether complete. After they reach maturity, the seeds are dispersed for a 1 to 2 week period from April through July.