From Opus

This article has been marked for merging It has been discussed that this article be merged with Sharp-shinned Hawk.

Accipiter striatus chionogaster

Photo by Tom Jenner

[edit] Identification

Between 26-37 cm in length (based on the measurements of 26 specimens in the collection of the British Museum at Tring), with females significantly larger than males.

Adult: Iris orange to red, with older birds probably having the redder eye colour. Cere and legs yellow. Entire upperparts brown to slate grey. Males tend to have greyer plumage, which can appear almost blue-grey in certain light. Some females (possibly the older ones) have greyer plumage. Throat, breast, belly and under tail coverts white to pale cream. Thighs creamier to pale beige, but this feature rarely visible in the field. Underwing coverts white. Underside of flight feathers white with broad dark bands.

Immature: birds have browner flight feathers which contrast with the upperparts.

Juvenile: Similar to adult, but with yellow eye, browner upperparts. Tend to show a faint white supercilium. Orangy brown marks on the underparts vary from faint streaks to thicker arrow-head shapes and from being limited to just the breast to being on much of the underparts.

[edit] Similar species

In size, shape, behaviour and call, this species is very similar to the closely related Sharp-shinned Hawk Accipiter striatus, which is sympatric during the northern winter. Best identified by underpart colouration: adult Sharp-shinned Hawk has rufous barring on the underparts, while the juvenile has thick brown streaks, that are not likely to be confused with the much fainter streaks on a juvenile White-breasted Hawk.
Bicolored Hawk A. bicolor, which is unlikely to be found in the same habitat, is significantly bigger. The adult has grey underparts and the juvenile has more buffy underparts than is found on White-breasted Hawks. Collared Forest-Falcon Micrastur semitorquatus can be found in the same habitat. It is considerable larger and in all plumages shows a paler collar that extends around the nape.

[edit] Distribution

The species has a very limited world distribution, limited to the highlands of south eastern Mexico (Chiapas and the eastern tip of Oaxaca), southern Guatemala, northern El Salvador, Honduras, and western Nicaragua. The species is probably sedentary, though there are unconfirmed extralimital records in published lists from Tikal in northern Guatemala (Beavers 1992) and Monteverde in Costa Rica (Fogden 1993).

[edit] Taxonomy

This monotypic species is often considered a race of Sharp-shinned Hawk A. striatus (eg by the AOU), along with the two South American species Plain-breasted Hawk A. ventralis and Rufous-thighed Hawk A. erythronemius. All four forms are clearly closely related, though there has been little attempt to make a comparative study or DNA analysis. The main comparison was by Storer (1952), who described a cline in the patterning of resident Sharp-shinned Hawks in Mexico, with them getting paler to the south towards the range of White-breasted Hawk. However, the photos of specimens in his paper did not seem to show such a marked effect.

[edit] Habitat

The main habitat for this species is pine and pine oak forest, with all known nest sites being within this habitat. However, the species regularly ranges into neighbouring cloud forest, tropical dry forest and farmland to hunt for food.

[edit] Behaviour

Much of the behaviour of this species is similar to other Accipiters such as Sharp-shinned Hawk A. striatus and Eurasian Sparrowhawk A. nisus.

Nesting All known nests have been in Pinus oocarpa. Nest building is done by both adults, though most is done by the male. It begins as early as November and is complete by about mid April with 2 or 3 pale blue eggs with brown blotches being laid. Eggs in nest from about late March to mid May. Chicks fledge late May to July. All incubation is by the female.

Feeding Mainly feed on birds ranging in size from Black-throated Green Warbler Dendroica virens to Band-tailed Pigeon Patagioenas fasciata, though lizards and a bat have also been recorded. Hunting is mainly by surprise and done by a sudden dive or acceleration from a perch. Female is fed by the male from the later stages of nest building, through incubation, until the chicks are a couple of weeks old. Older chicks are brought food by both parents.

Calls The two main adult calls, heard mainly near the nest, are a long high pitched eeeeeee eeeeeee, which is often given by the female after receiving food or by juveniles begging for food, or a much faster series of notes ee ee ee ee ee that tend to be given when food is brought in or during times of alarm. Chicks in the nest sometimes give high pitched, whispered whistles swee swee swee when handled.

[edit] References

1. Beavers, R. A. (1992) The Birds of Tikal: An annotated checklist for Tikal National Park and Peten Guatemala. Texas A and M University Press.
2. Fogden, M. (1993) An Annotated Checklist of the Birds of Monteverde and Peñas Blancas. Private publication.
3. Storer, R. W. (1952) Variation in the resident Sharp-shinned Hawks of Mexico. Condor, 54, 283-9.

[edit] External Links

A page on this species with many photographs is found in the bird database of Mayanbirding [1]