The broad-winged hawk (Buteo platypterus) is a small to medium-sized raptor belonging to the Buteo genus. It is the smallest Buteo in the Midwest. They are carnivores and their diet depends on the time of year and consists of whichever insects, amphibians, reptiles, mammals, and birds are available. These hawks are native to the Nearctic and Neotropical regions, with some subspecies distributed over eastern North America during the summer, as far west as British Columbia and Texas. They migrate south to winter in the Neotropics, from Mexico south to southern Brazil. Other subspecies are all-year residents on Caribbean islands.
Physical Characteristics
The broad-winged hawk is a relatively small Buteo, with a body size from 32 to 44 cm (13 to 17 in) in length and weighing 265 to 560 g (9.3 to 19.8 oz). Females are slightly larger than males. The wingspan ranges from 81 to 100 cm. Broad-winged hawks' wings are relatively short and broad with pointed wing tips, which have a tapered appearance unique to the species. The tail is relatively short, measuring 14.5-19.0 cm (5.7-7.5 in) in length. The tarsus measures from 5.6 to 6.6 cm (2.2 to 2.6 in).
Adult broad-winged hawks have a dark brown back and a light breast and belly. The adult has reddish horizontal barring underneath, while the immature bird's barring runs vertically and is browner. The tail of the adult is brown to gray with broad white stripes, and the immature bird's tail is brown with a light-black terminal band. Adults have a black border to the trailing edge of the wings, but juveniles lack the dark trailing edge. Juvenile broad-winged hawks look similar to adults but are lighter underneath with brown streaking and have narrower bands on the tail.
There are two types of coloration: a dark morph with fewer white areas and a light morph that is more pale overall. The light morph of this bird is most likely to be confused with the red-shouldered hawk, which has a longer, more heavily barred tail and wings with a solid rufous color in the adult, which are usually distinctive. Rare dark morphs are a darker brown on both upperparts and underparts.
Distribution and Habitat
The broad-winged hawk is a hawk of eastern deciduous woodlands and is not found west of the Rocky Mountains. Its range extends in the north from Alberta east to Nova Scotia, south through North Dakota, Minnesota, and Iowa to eastern Texas, through the Gulf coast to northern Florida. They breed in large deciduous or mixed forests throughout the eastern United States and southern Canada.
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Found in dense, unbroken deciduous or mixed deciduous/coniferous woodlands, the broad-winged hawk utilizes parts of woodlands for nesting that the red-tailed hawk and red-shouldered hawk do not, sometimes in residential backyards. They usually nest near forest openings and bodies of water, and far from areas of human disturbance. Broad-winged Hawks stay in areas up to an elevation around 2,000 m (6,600 ft).
They are classified as complete migrants flying south to winter in Central and South America. Migrants roost on edges of tropical forests, cloud forests, and in arid tropical scrub. Some immature birds winter in south Florida and the Florida Keys, using mango and avocado groves, as well as undisturbed West Indian hardwood stands on the larger keys. Most Broad-winged Hawks, however, winter in forests and along forest edges from southern Mexico to Brazil and Bolivia, usually preferring upland sites. Five subspecies are endemic to the Caribbean and do not migrate. Those subspecies that do migrate fly in flocks of more than 40 up to several thousand at heights from 550 to 1,300 m (1,800 to 4,270 ft).
Breeding and Nesting Habits
Broad-winged hawks are monogamous. They return to their breeding grounds in the spring, around mid- to late-April. Broad-winged hawks breed between April and August, raising one brood per summer. Nest building typically begins in late April through mid-May. Both the male and female build the nest, a process that takes 2 to 4 weeks. They often add a ring of sticks on top of an old squirrel nest in the crotch of a deciduous, or on occasion, a coniferous tree. Nests are rarely used for two consecutive years.
The nest site is usually in the lower part of a large tree (either deciduous or coniferous), typically 25-40' above ground. The nest (built by both sexes) is a rather small platform of sticks, lined with softer materials such as bark and moss. Leafy green twigs are often added during the nesting cycle. Often uses pre-existing nest of hawk, crow, or squirrel, adding material to it. The nest is in the lower third of the canopy, usually in the first main crotch of a deciduous tree or on a platform of horizontal branches against the trunk of a conifer. Pairs sometimes reuse their nests from previous years or renovate old nests of other species.
The female does most of the nest construction, assisted by the male. They collect dead sticks from the ground and carry them in their talons into the nest tree to build the main structure of the nest. The female brings bark chips and fresh plant sprigs in her beak to build the nest cup. They spend 2-4 weeks building the nest, which occasionally contains materials such as corn husks, moss, grapevine, lichen, feathers, and pine needles. The nest measures 12-21 inches across and 5-12 inches high on the outside, with an inner cup 6-7 inches across and 1-3 inches deep.
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The female lays 1 to 4 (usually 2 to 3) eggs at 1 to 2 day intervals. The eggs are typically 49 mm × 39 mm (1.9 in × 1.5 in) and weigh about 42 g (1.5 oz). The eggs can be white, pale cream, or a little bluish, with a granulated surface; either unmarked or with variable brown markings. Incubation is almost entirely by female, 28-31 days. Male brings food to female during incubation, then he may sit on eggs while she eats. The hatchlings will appear semialtricial, incapable of any complex coordination, but have open eyes and are covered in down feathers. Female remains with young almost constantly for first 1-2 weeks after they hatch; male brings food, and female feeds it to nestlings.
Chicks have rapid body growth until they are almost at adult body size, when they are capable of walking, flying, and eating without parental help. After hatching, the female stays in the nest and the female tears the food into pieces and feeds it to the chicks. After 2 weeks, the female begins leaving the nest to hunt. Young may climb out of nest onto nearby branches at about 4-5 weeks; can fly at about 5-6 weeks, and soon start learning to hunt. The hatchlings need 5-6 weeks before they are able to leave the nest. Brood reduction (siblicide among nestlings) does occur in broad-winged hawks, but it appears to be uncommon.
Hunting and Feeding Ecology
Broad-winged hawks are carnivores. The types of food they eat depends on the time of year and consists of whichever insects, amphibians, reptiles, mammals (ranging from mice to small rabbits), and birds (up to the size of grouse and New World quails) are available at any given time. During the summer or nesting season the parents and ultimately their chicks eat small animals such as chipmunks, shrews, and voles, frogs, lizards, and sometimes even other nesting birds like cardinals, as well as sick or injured birds. In the winter, they have been observed feeding on insects (such as grasshoppers, dragonflies, and saturniid moth caterpillars), frogs, lizards, snakes, crabs, earthworms, and small mammals.
During the nesting season, mammals-primarily chipmunks, shrews, and voles-are common in their diets, along with frogs, lizards, and nestling birds. On the wintering grounds of South America, insects, lizards, and frogs seem to make up the majority of their diet.
Broad-winged hawks hunt from a perch, usually located along edge of woods or near water. They watch for food from perches on tree limbs (often below the canopy and in the forest interior) as well as places such as utility poles near forest edges. When prey is spotted, the hawk swoops down rapidly to capture the creature in its talons. They only occasionally hunt on the wing. From their roost they do a short, fast glide to capture the prey.
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Their most frequent prey items are frogs, toads, and small rodents, but they have a broad diet that includes invertebrates, amphibians, reptiles, mammals, and birds (mostly nestlings and juveniles). Their invertebrate prey includes mantises, crickets, grasshoppers, caterpillars, ants, junebugs, click beetles, ground beetles, flies, spiders, earthworms, and crabs. They give special attention to preparing their food for consumption, skinning frogs and snakes and plucking prey birds' feathers. Most small mammals are eaten whole.
Behavior and Communication
Broad-winged hawks are solitary and territorial, except during migration. They are one of the few raptor species in North America that migrates in flocks. These flocks can also contain other raptors. Broad-winged hawks are excellent at soaring. They also use vocalizations and physical displays to communicate. There are four recognized calls that are used by broad-winged hawks. They whistle to advertise occupancy of a territory.
To attract and court females, the males perform a courtship display flight including cartwheels, dives, and other aerial acrobatics. Early in breeding season, pairs circle high in the air, calling. In display, one bird may fly high, then dive steeply toward the ground. Birds meet in the air, hook their feet together and spiral down together. They also compete and fight with other males for the chance to mate with a female.
Broad-winged hawks protect their nests in a show of aggression (i.e. diving and chasing) towards any suspected threat, but they generally do not make physical contact. Predators of eggs and nestlings include raccoons, crows, porcupines, and American black bears. Adults have been known to fall to red-tailed hawks, great horned owls, bald eagles, and golden eagles.
Conservation Status
Considered to be one of the most common hawks in North America with approximately one million birds making up the North American population. They are very common in the Midwest. Broad-winged hawks affect the local populations of the animals they eat. They are classified as a species of least concern by the IUCN.
Broad-winged Hawks are numerous, and their populations slightly increased (particularly in Canada) between 1966 and 2019, according to the North American Breeding Bird Survey. Partners in Flight estimates the global breeding population at 1.9 million and rates them 9 out of 20 on the Continental Concern Score, indicating a species of low conservation concern. However, the Puerto Rican subspecies of Broad-winged Hawk is on the Watch List and is listed as Endangered under the Endangered Species Act.
The broad-winged hawk gained suitable breeding habitat as it became reforested in the past century, but this benefit could be offset by increasing human development, since Broad-winged Hawks usually nest in large forests away from human activity. Migration numbers dropped in the east in the 1990s, possibly due to population decline or perhaps simply because of a change in migration patterns. The largest threat to this species is habitat destruction, particularly within its wintering range. Hunting was a common practice in the early twentieth century during breeding and migration, and it continues today on the wintering grounds.