Chilean Hawk (Accipiter chilensis)

Chilean Hawk

[order] ACCIPITRIFORMES | [family] Accipitridae | [latin] Accipiter chilensis | [authority] Philippi and Landbeck, 1864 | [UK] Chilean Hawk | [FR] Epervier du Chili | [DE] Chile-Sperber | [ES] Gavilan Chileno | [NL] Chileense Sperwer

Subspecies

Genus Species subspecies Region Range
Accipiter chilensis SA sw

Genus

Members of the genus Accipiter are small and medium-sized hawks, often called Sparrow-hawks or Goshawks. The females are almost invariably much larger than the males – in some cases weighing twice as much – a level of size dimorphism only exceptionally reached in any other genus Falconiformes. Their wings are short and rounded; the tail usually quite long. They are well adapted for flying through dense bush. Bird-catching Sparrow-hawks generally have long and slender legs, with slender digits, the middle one being especially long. Goshawks are usually larger, with shorter, thicker tarsi and digits and a shorter middle digit. Some smaller species have goshawk-like feet and vice versa, making it difficult on a world-wide basis to subdivide the genus on this or any other broad basis. Although many accipiters feed upon birds moreso than do other hawks, some species take many mammals, especially squirrels; others take lizards, frogs, snakes, insects, even snails. In these species the legs and digits are sometimes slender, but short. Accipiters are rarely crested, but some have very attractive colour patterns. Black phases are present, especially in the tropical species. One in Australia has the only pure white phase. Accipiter is the largest genus in the family, having about fifty species. It is present worldwide, but is especially rich in Papua-New Guinea, where a small island like New Britain may have three to five endemic species or distinct sub-species.

Physical charateristics

The male is 37 to 38 cm long, while the larger female measures 41 to 42 cm. The adults have black upperparts, and an ash-grey chest and abdomen with dark barring. The throat has longitudinal dark stripes and the undertail is white. The uppertail is brown with 5 or 6 dark bands. The legs are greenish yellow, and the eyes are yellow. The sexes have similar plumage. Young birds have browner upperparts with cream fringes to the feathers. The paler chest and abdomen have longitudinal stripes. The paler uppertail makes the banding more obvious.


wingspan min.: 0 cm wingspan max.: 0 cm
size min.: 35 cm size max.: 42 cm
incubation min.: 19 days incubation max.: 23 days
fledging min.: 0 days fledging max.: 0 days
broods: 1   eggs min.: 1  
      eggs max.: 4  

Range

South America : Southwest

Habitat

The Chilean Hawk is specifically found in temperate forest. Far more rarely, it is also found in sclerophyllous forest, parkland and mixed forest and open habitat. Top hunt, it also visits open areas like shrubland, grassland or agricultural land to hunt. It is rarely if ever seen in heavily human-modified habitat however, and the few individuals that have been encountered in city parks and gardens are probably not resident birds. As it seems, it requires not much less than 200 hectares of native forest to breed

Reproduction

The oval platform nest measures about 50-80 by 50-60 cm and is some 25 cm high when freshly built. Some nests are more than twice as high; these might have been used in several years. It is built from strongly intertwined dry twigs and sticks. It is placed on forked branches in the upper part of a tree, close to the main trunk or a main vertical branch, some 16-20 m above ground. At least locally, full-grown coihue trees (Nothofagus dombeyi) seem to be much preferred for nesting. Nests are sometimes reused in successive seasons, but more often a new nest is constructed in a different tree every season. The clutch is probably two, sometimes three and rarely one, as usual for Accipitridae. The eggs are dull light bluish to off-white all over and are shaped like a chicken’s egg. The eggshell’s inside has a slightly more pronounced bluish tinge. Incubation lasts probably about 3 weeks. The parents defend their nesting grounds against other birds of prey, such as the Red-backed Hawk (Buteo polyosoma); during approaches by such potentially dangerous species, the nestlings will tuck away their heads. It seems that 2 or 3 young are raised on a regular basis, unlike in many other Accipitridae where only the strongest nestling survives

Feeding habits

It is not well-known how this carnivore catches its prey, but as it seems it is optimized for pursuit of small and maneuvrable birds throughout all levels of the forest. It is also able to seize large insects in mid-air. Both active searching for prey and sitting in ambush to wait what might come along has been observed. Buring the breeding season, pairs may cooperate in hunting; their different sizes ensures that they do not compete for prey much. The Chilean Hawk’s food is almost exclusively birds (97.8% of all prey remains in one study),[2] in particular a diverse selection of forest passerines. More than 30 bird species are documented to be eaten by this hawk at least occasionally. Rodents of at least 4 species and every now and then an occasional insect or squamate round off its diet.
The Chilean Hawk hunts forest passerines quite indiscriminately of species, habitat or habits provided they have the right size, though it has a preference for species that live closer to the forest floor. Depending on availability, favorite prey species include Thorn-tailed Rayadito (Aphrastura spinicauda) Black-chinned Siskin (Carduelis barbata), White-crested Elaenia (Elaenia albiceps), Austral Thrush (Turdus falcklandii) and Fire-eyed Diucon (Xolmis pyrope). It has been claimed that the Chilean Pigeon (Columba araucana) constitutes important prey, but this seems only to be correct at certain times or places, if at all.

Conservation

BirdLife International considers Accipiter chilensis to be a subspecies of A. bicolor, so is not categorized separately as a species
It is listed as a rare or insufficiently known species in Chile and legally protected under the Hunting Law. In Argentina it is not listed as threatened. On a global scale, it is a rare bird, though not under immediate threat. Populations may decline due to increasing habitat loss from extensive fires, logging pressures, and hunting. It is not evaluated by the IUCN, as they do not consider it specifically distinct, but is included on the CITES Appendix II as part of the blanket listing of Falconiformes.

Migration

Part of population migrates to Northwest Argentina, perhaps following northbound migratory passerines. Limits of transition between migratory and resident populations not known.

Distribution map

Chilean Hawk distribution range map

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