Red-tailed Hawk (Buteo jamaicensis)

Red-tailed Hawk

Description

The red-tailed hawk (Buteo jamaicensis) is a bird of prey that breeds throughout most of North America, from the interior of Alaska and northern Canada to as far south as Panama and the West Indies. It is one of the most common members within the genus of Buteo in North America or worldwide. The red-tailed hawk is one of three species colloquially known in the United States as the "chickenhawk", though it rarely preys on standard-sized chickens. The bird is sometimes also referred to as the red-tail for short, when the meaning is clear in context. Red-tailed hawks can acclimate to all the biomes within their range, occurring on the edges of non-ideal habitats such as dense forests and sandy deserts. The red-tailed hawk occupies a wide range of habitats and altitudes, including deserts, grasslands, coniferous and deciduous forests, agricultural fields, and urban areas. Its latitudinal limits fall around the tree line in the Arctic and the species is absent from the high Arctic. It is legally protected in Canada, Mexico, and the United States by the Migratory Bird Treaty Act. Red-tailed hawk plumage can be variable, depending on the subspecies and the region. These color variations are morphs, and are not related to molting. The western North American population, B. j. calurus, is the most variable subspecies and has three main color morphs: light, dark, and intermediate or rufous. The dark and intermediate morphs constitute 10–20_ of the population in the Western United States, but seem to constitute only 1–2_ of B. j. calurus in western Canada.[28][29] A whitish underbelly with a dark brown band across the belly, formed by horizontal streaks in feather patterning, is present in most color variations. This feature is variable in eastern hawks and generally absent in some light subspecies (i.e. B. j. fuertesi). Most adult red-tails have a dark-brown nape and upper head, which gives them a somewhat hooded appearance, while the throat can variably present a lighter brown "necklace". Especially in younger birds, the underside may be otherwise covered with dark-brown spotting, and some adults may too manifest this stippling. The back is usually a slightly darker brown than elsewhere with paler scapular feathers, ranging from tawny to white, forming a variable imperfect "V" on the back. The tail of most adults, which gives this species its name, is rufous brick-red above with a variably sized, black subterminal band and generally appears light buff-orange from below. In comparison, the typical pale immatures (i.e. less than two years old) typically have a mildly paler headed and tend to show a darker back than adults with more apparent pale wing-feather edges above (for descriptions of dark morph juveniles from B. j. calurus, which is also generally apt for description of rare dark morphs of other races, see under that subspecies description). In immature red-tailed hawks of all morphs, the tail is a light brown above with numerous small dark brown bars of roughly equal width, but these tend to be much broader on dark morph birds. Even in young red-tails, the tail may be a somewhat rufous tinge of brown.[30] The bill is relatively short and dark, in the hooked shape characteristic of raptors, and the head can sometimes appear small in size against the thick body frame. The cere, the legs, and the feet of the red-tailed hawk are all yellow, as is the color of bare parts in many accipitrids of different lineages.[31] Immature birds can be readily identified at close range by their yellowish irises. As the bird attains full maturity over the course of 3–4 years, the iris slowly darkens into a reddish-brown, which is the adult eye-color in all races.[30] Seen in flight, adults usually have dark brown along the lower edge of the wings, against a mostly pale wing, which bares light brownish barring. Individually, the underwing coverts can range from all dark to off-whitish (most often more heavily streaked with brown) which contrasts with a distinctive black patagium marking. The wing coloring of adults and immatures is similar but for typical pale morph immatures having somewhat heavier brownish markings.[27]

Distribution And Habitat

The Red-tailed Hawk occurs from North America through Central America including the Caribbean (Raffaele and others 1998, Root 1988). It is widespread and fairly abundant throughout Puerto Ricos mainland, but it is most numerous in the mountains (Biaggi 1997, Bond 1961, Rivera- Milán 1995b, Santana and Temple 1988). It is also known to inhabit satellite islands such as Desecheo (Meier and others 1989), Culebra (Wetmore 1917), and Vieques (Sorrié 1975, Wetmore 1916), in the latter being a fairly common resident (Gemmill 2015). This species generally occurs on all habitats at all elevations including towns and urban areas (Oberle 2018, Raffaele and others 1998, Rivera-Milán 1995b, Santana and Temple 1988). The atlas fieldwork yielded a total of 646 records within 355 hexagons or 74 percent of the 479 total hexagons (see map). Of the 355 hexagons where this species was found, breeding met the atlas definition of confirmed in 29 percent (102) of the hexagons, probable in 23 percent (83), and possible in 48 percent (169), while it was observed in an additional hexagon (<1 percent) but without evidence of breeding (see map). Red-tailed Hawk distribution. The map shows the highest breeding code by hexagon and overlaying the ecological life zones in Puerto Rico. Note: percentages may not total 100 due to rounding. 173Red-tailed Hawk/Guaraguao Colirrojo

Breeding Habits

The Red-tailed Hawk builds a large and bulky nest made of sticks, which is usually placed high in a tree or on the side of a cliff (Santana and Temple 1988, Santana and others 1986). Previously published reports indicate that it breeds from January to July (Raffaele and others 1998), but Santana and Temple (1988) describe a November-to-August breeding period. Overall, the breeding activity peaks in June, and it mostly takes place in the subtropical moist forest life zone, which is consistent with survey results of Rivera-Milán (1995b). Atlas results show that this species breeding season extends throughout the year with the most breeding activity from March to June (see chart). Results show that this species breeds throughout the island but mostly within the subtropical moist forest life zone (58 percent of the hexagons) (see table and map). It also breeds in the subtropical wet and lower montane wet forest life zones, and subtropical rain forest life zones at higher elevations (23 percent and 1 percent of the hexagons, respectively), and in the subtropical dry forest life zone as well (18 percent of the hexagons) (see table and map).

Conservation

The current population trend of the Red-tailed Hawk is described as increasing (Butcher and Niven 2007). This species is currently listed as a species of least concern by the IUCN (BirdLife International 2016). Locally, this species is not listed in any of the threatened categories of PRDNER and USFWS. In Puerto Rico, the Red-tailed Hawk has a protected habitat in land of 12 percent or 992 km2 of the total area covered by the hexagons where evidence of breeding was found for this species (8466 km2).