Recent phylogenies of the buteos based on mitochondrial DNA sequences place Buteo brachyurus in a clade with Buteo swainsoni, Buteo galapagoensis, Buteo solitarius, and Buteo albigula. All of these species are primarily Neotropical species, with only short-tailed hawks and B. swainsoni having significant presences in North America. It is hypothesized that these hawks had a common ancestor similar to B. swainsoni that was a long-distance migrant capable of colonizing distant oceanic islands.
The voice of Buteo brachyurus is described as a high-pitched, prolonged “keeeea” and it is often given when humans approach the nest. They also give a "keeee" call at the nest site, especially when males return to incubating females. A "squeee" call is also given before or after copulation and sometimes by a female when she is receiving food from a male. During the non-breeding period, these birds are usually silent. Newly hatched chicks give chip calls singly or in series of 2 to 4. After about four days they will call for food with soft squeals.
Communication Channels: visual ; acoustic
Perception Channels: visual ; tactile ; acoustic ; chemical
Buteo brachyurus is listed as Least Concern on the IUCN Red List. Short-tailed hawks are protected under the US Migratory Bird Act. They are not given any special status on the US Federal Endangered Species list nor are they listed under CITES Appendix II. Though uncommon to rare throughout most of their range, short-tailed hawks are not currently threatened. The Florida population, however, is at risk due to its small size (estimated at 500 individuals), geographic isolation, poor breeding success, and continuing loss of prairie, swamp forest, and mangroves.
US Migratory Bird Act: protected
US Federal List: no special status
CITES: no special status
State of Michigan List: no special status
IUCN Red List of Threatened Species: least concern
There are no known negative effects of short-tailed hawks on humans.
Short-tailed hawks may aid farmers by occasionally preying on rodents that feed on their crops.
Positive Impacts: controls pest population
Short-tailed hawks are important predators, especially of birds, in the ecosystems they inhabit.
Short-tailed hawks feed mostly on smaller birds. In Florida, over half their bird diet is made up of eastern meadowlarks (Sturnella magna) and red-winged blackbirds (Agelaius phoeniceus), likely due to the conspicuousness of these species. They prey on adults of these species and have not been observed feeding on nestlings. When hunting, they hover or soar 50 to 300 meters high, with outstretched wings and head held down. From this position, they can dive on birds below. They also prey on lizards, snakes, rodents, and occasional insects (wasps and grasshoppers). They can catch prey on the wing, as well as when the prey is on a conspicuous perch. Ogden et al. (1974) report hunting success to be relatively low (~11%) with only 12 of 107 attempts being successful over the course of 30 hours of observation. Nestlings produce pellets of indigestible material about 30x12 mm in size.
Animal Foods: birds; mammals; reptiles; insects
Primary Diet: carnivore (Eats terrestrial vertebrates)
Short-tailed hawks occur in the Nearctic and Neotropical regions. In the United States, short-tailed hawks reside mainly in southern Florida. In recent years they have been expanding their range northward to southern Texas, Arizona, and New Mexico, although no breeding has yet been reported in these states. Their range extends from the northern areas of Mexico to as far south as northern Argentina. A related taxon, Buteo albigula, which occurs in the temperate zone of the Andes and parts of Chile, was formerly considered a subspecies of short-tailed hawks but it is now generally given full species status.
Many populations appear to be migratory. Populations in Mexico may migrate as far south as Costa Rica. The population in Florida is disjunct by about 800 km from other populations and is partially migratory. In that population, individuals breed throughout most of the peninsula north to north-central Florida, but migrate during the winter to the southern tip of the peninsula and some of the Florida Keys. Populations from Panama and throughout South America are not known to migrate.
Biogeographic Regions: nearctic (Native ); neotropical (Native )
Short-tailed hawks breed mainly in tall, dense, wet forest patches near water, such as mangrove and cypress swamps. When not breeding, individuals can be found near coastal areas, forests, forested edges, pine savannas, pastures, suburban areas, and open country. They are not usually found in dense, closed forest. While they often roost and nest in larger trees, they hunt primarily in open country and on forest edges, where wind conditions are best for their unique style of hunting. Buteo brachyurus occurs primarily in lowland and foothill habitats, typically up to 2000 m elevation and occasionally to 3000 m. Robinson et al. (1994) reports short-tailed hawks inhabiting a wide range of habitats in Amazonian Peru, including lake, rivers, pantanal (seasonally flooded wetlands mainly in southern Brazil), transitional forests, and upland forests, though they were considered rare in all of these except pantanal, where they were considered uncommon.
Range elevation: 3000 (high) m.
Habitat Regions: temperate ; tropical ; terrestrial
Terrestrial Biomes: savanna or grassland ; forest ; rainforest ; scrub forest
Aquatic Biomes: coastal
Wetlands: swamp
Other Habitat Features: suburban ; riparian ; estuarine
There is no information on lifespan or survivorship in short-tailed hawks. Recorded causes of death include being shot, as well as being hit by cars. Habitat destruction, especially of winter breeding grounds in Florida, may also contribute to death in short-tailed hawks. Ironically, short-tailed hawks have increased in density in some areas due to logging that has opened up more of the forest edge habitats that it prefers (Thiollay 1999).
Short-tailed hawks, one of the smaller species of Buteo, are crow-sized birds. They are 39 to 44 cm in length with a wingspan of 83 to 103 cm. The tail grows to 132 to 340 mm. Average mass is 441 grams. Females are larger than males, weighing on average 515 grams, while males weigh 392 grams on average. Though females are larger than males, the sexes are similar in the field. They have relatively long wings for their size; when perched, the wings reach the tail tip, giving these hawks their name due to the appearance of having an unusually short tail. In reality tail length is typical of the genus. The bill is black with a bluish-black base and a cere that varies from yellow to greenish-yellow. The legs and feet are light yellow to lemon yellow while the talons are black. The iris of Florida birds are dark brown in adults and lighter brown in juveniles. Museum specimens from tropical areas have irises ranging from yellow to yellowish-brown to brownish-yellow.
Short-tailed hawks occur in distinct light and dark color morphs with no intermediates. The light morph has white, unmarked underparts and underwing coverts while the head is a very dark blackish brown except for the anterior portions of the malar region, lores, chin, and throat, creating the effect of a dark hood. The upper parts and upper wing coverts are a uniform blackish brown with small patches of rufous brown on the sides of the upper breast, sides of the rump, and the scapulars. The tibial and crural feathers are pale buff. The under surface of the flight feathers is pale grayish with many narrow brownish bars and one wide dark terminal band along the trailing edge of the wing. The primaries are palest at the base of the outer first through fifth primaries, creating a diagnostic white oval. The rectrices appear grayish-brown above and grayish-white below with 4 to 5 narrow, incomplete brown bands and a dark terminal band. The tip of the tail feathers are pale gray. Sexes are alike.
The dark morph is almost entirely blackish brown. It lacks the rufous brown on the rump and scapulars and there is a small white patch where the lore and forehead meet. The underwing coverts are dark blackish brown except for the greater secondary and primary underwing coverts, which are mottled with white. The rest of the underwing appears the same as the light morph. Sexes are alike. In Florida, the dark morph is more numerous than the white. In other parts of the species’ range, the dark morph is uncommon or nonexistent.
Immature light morph short-tailed hawks have pale buff or orange-buff on the breast, belly, crural feathers, axillaries, and underwing coverts. The dark bands on the tail are heavier and more numerous than those on the adult, they are all roughly the same width. There are dark-brown streaks on the side of the breast and the edge of the feathers of the nape, scapulars, back, rump, and wing coverts have pale-brown or pale-buffy coloration. Instead of the hood of the adult, light-morph juveniles have ear coverts finely streaked with buff or pale ocher. Dark morph immature hawks have white spots and streaks on their chin, throat, belly, breast, axillaries, and under wing coverts.
There are two recognized subspecies of Buteo brachyurus: B. b. brachyurus and B. b. fuliginosus. Buteo brachyurus brachyurus is found in in South America. It can be distinguished from Buteo brachyurus fuliginosus by having less barring on the tail and no rufous on the side of the neck. Buteo brachyurus fuliginosus is found in Panama and the rest of the North American range. Though they are considered part of the same subspecies, the population of hawks in Florida appears to be larger-bodied than those living in Central and South America. They also have more rufous on their hind neck.
Range mass: 392 to 515 g.
Average mass: 441 g.
Range length: 39 to 44 cm.
Range wingspan: 83 to 103 cm.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry ; polymorphic
Sexual Dimorphism: sexes alike; female larger
There are no known predators of adult short-tailed hawks. Crows have been known to rob the nest of eggs.
Known Predators:
The breeding season of short-tailed hawks is from late January to July. These birds are presumed to be monogamous. Courtship consists of the male circling and undulating above the female who is perched at the nest site. The male then presents prey or nest material to the female. They have also been observed to grasp each others’ talons in the air and tumble earthward. Copulation begins with the male descending and landing near or on the female. He proceeds to give a two-note squeal before mounting for 5 to 7 seconds. Though one male was observed to have had 2 mates over three years, there is little information on the duration of pair bonds. There is no assortative mating between the two color morphs. During the breeding season short-tailed hawks becomes quite secretive and can then be difficult to locate.
Mating System: monogamous
Females create a platform nest made of sticks, lining the interior with finer twigs and soft material such as Spanish moss during incubation and hatching. Males gather nest materials. Nests are around 0.6 to 0.9 meters wide and 0.3 meters deep. Normally, they are located towards the top of taller trees, 9 to 29 meters up, in cypress swamps or mangroves. Less often, nest sites are found in the interior of both closed and open woods and the edges of hammocks. One to three preliminary nests may be constructed before a final nest is chosen. Nests may be reused year after year, and new nests are always located around the same area as previous ones. Only one brood is raised per season.
Buteo brachyurus normally lays two eggs, although clutch size varies from one to three eggs. Typically they are an unspotted bluish-white, although some have reddish brown speckling around the larger end. The eggs are short elliptical or nearly oval shape. The length of time between eggs in a clutch is unknown. Incubation lasts between 34 and 39 days. Females incubate eggs while males provisio females with food.
At hatching, young are covered in white natal down and weigh from 35 to 55 grams. About 2.5 to 3 weeks after hatching, a second layer of gray down is grown. Nestlings are brooded almost continuously as females are absent from the nest less than 10% of the time. Chicks are fed 2 to 3 times a day by both parents. Siblicide has not been well-documented in the species, although observations in captivity suggest that it is a possibility. Length of time to fledging is unknown. One specimen had a mass of 415 grams at fledging. In an estimated 45% of nests, at least one young is successfully raised. The age at sexual maturity is unknown; however first-year birds have not been observed breeding. The timing of molts in this species is also unknown.
Breeding interval: Short-tailed hawks breed once every year.
Breeding season: Short-tailed hawks breed from January to July.
Range eggs per season: 1 to 3.
Range time to hatching: 34 to 39 days.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization ; oviparous
Short-tailed hawk males and females both care for their young until they are fledged and independent.
Parental Investment: altricial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Male, Female); pre-weaning/fledging (Provisioning: Male, Female, Protecting: Male, Female); pre-independence (Provisioning: Male, Female, Protecting: Male, Female)
The short-tailed hawk (Buteo brachyurus) is an American bird of prey in the family Accipitridae, which also includes the eagles and Old World vultures. As a member of the genus Buteo, it is not a true hawk and thus also referred to as a "buteo" or (outside North America) "buzzard". The white-throated hawk (B. albigula) is a close relative and was formerly included in the species B. brachyurus.
Short-tailed hawks breed in the tropical and subtropical Americas from southeastern Brazil and northern Argentina north through Central America to the mountains of the Mexico-Arizona border area, as well as in southern Florida, United States; it is also found on the Caribbean island of Trinidad. This species is generally found below 4,500 ft (1,400 m) ASL and most common below 2,500 ft (760 m). It is replaced by the white-throated hawk (B. albigula) in the Andes of southern Colombia and south to central Argentina and Chile; the short-tailed hawk is found in the Cordillera Central and Cordillera Occidental of Colombia, while B. albigula occurs south of these locales.[3] As far as is known, B. brachyurus is a year-round resident except that most of the Florida population migrates in winter to the southern tip of the state, including the Keys. It is somewhat habitat adaptable but only passes areas with dense human populations when foraging. The species may be found in wooded savannah, patchy woodlands near water, cypress swamps, mangrove swamps or high pine-oak woodlands. In the tropics, it is most common in lowland foothills.[4]
Most of what is known about its natural history has been studied in the Floridian population, and might not apply to birds at the south of the species' range. In general, this species is associated with woodland, often near water.
In Florida, it eats mainly smaller birds (such as ground doves).[5] The short-tailed hawk hunts from a soaring flight, often at the borders between wooded and open areas. A frequent maneuver is "kiting" – coming to a stop, the bird heads into the wind, with its wings held stationary. It typically attacks prey with a nearly vertical swoop, sometimes pausing and then continuing downward in a "stair-step" manner. Typical prey ranges from a New World warbler (Parulidae) to a bobwhite (Colinus sp.) in size. In Florida, icterids—namely the red-winged blackbird (Agelaius phoeniceus), the common grackle (Quiscalus quiscula), the boat-tailed grackle (Quiscalus major) and the eastern meadowlark (Sturnella magna)—make up the bulk of the prey. In one case, 95% of a single hawk's prey selection was found to consist of red-winged blackbirds.[6] Hunting success is apparently relatively low. In one study, 30 hours of observation showed that only 12 of 107 hunting attempts (or around 11%) were successful.[7] There are isolated records of short-tails preying on sharp-shinned hawks (Accipiter striatus) and American kestrels (Falco sparverius). Among tropical populations, they are several records of this species regularly taking frogs (especially tree frogs), lizards, snakes, large insects such as wasps and locusts.[8] Such prey, which serves merely as alternate foods for Florida populations, apparently provides a much larger proportion of the diet in tropical populations. In all parts of the range, they occasionally supplement their diet with smallish mammals, principally small rodents such as mice, rats, and bats.[9] Among the heaviest prey recorded are young common marmosets (Callithrix jacchus) and similar small monkeys; these do not seem to form an important prey item, however, and are only snatched when the opportunity presents itself.[10] They are primarily an aerial predator, taking most prey by swooping down to trees or the ground. Rarely, they have been recorded still hunting from a perch.[4]
The large stick nest is built in a tree, at a height ranging from 2.5 to 30 m (8.2 to 98.4 ft). In Florida, the bald cypress (Taxodium distichum) is a popular nesting tree of the short-tailed hawk. The nest is bulky, measuring 60–70 cm (24–28 in) wide and 30 cm (12 in) deep. Its 1–3 eggs per clutch are white, usually with dark spots and blotches. The nesting season is January through June in Florida and is possibly similar in the tropics. Incubation occurs over 34 days with no known details of their fledgling period.[4] In Florida, American crows have been known to consume eggs of this species.[11]
The short-tailed hawk is uncommon and local in most of its range. It is quite difficult to detect unless in flight, since it is often concealed while perched by dense canopy or with only the head showing (unlike most Buteo hawks which generally prefer prominent perches). Due to the fact that it is believed to be regularly overlooked in the field, no comprehensive population surveys have occurred for the species.[4] However, due to its wide extent of occurrence, it is not considered threatened by the IUCN.[1] Sightings of soaring short-tailed hawks are fairly frequent within their range. The Florida population is considered Critically Imperiled, and the Arizona population considered Imperiled by NatureServe.[12]
The short-tailed hawk (Buteo brachyurus) is an American bird of prey in the family Accipitridae, which also includes the eagles and Old World vultures. As a member of the genus Buteo, it is not a true hawk and thus also referred to as a "buteo" or (outside North America) "buzzard". The white-throated hawk (B. albigula) is a close relative and was formerly included in the species B. brachyurus.
