Aphelocoma
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Aphelocoma californica |
The passerine birds of the genus Aphelocoma[1] include the three scrub jays and two other jays. They are New World jays found in Mexico, western Central America and the western United States, with an outlying population in Florida. This genus belongs to the group of New World (or "blue") jays - possibly a distinct subfamily - which are not closely related to other jays, magpies or treepies (Ericson et al, 2005).
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[edit] Species
Five species of Aphelocoma are now recognized, since two taxa formerly treated as races of A. coerulescens were recently split off as separate species (A. californica and A. insularis); the 3 now separate species differ in color and bill size. They are believed to have evolved in the Pleistocene, and the Floridan species is known to have been recognizably distinct and present in its current range for at least 2 million years (Emslie, 1996).
- Western Scrub Jay A. californica – western United States from Washington to west Texas and south to Baja California and central Mexico
- Florida Scrub Jay A. coerulescens – Florida
- Island Scrub Jay A. insularis – Santa Cruz Island off southern California
- Mexican Jay or Gray-breasted Jay Aphelocoma ultramarina – Sierra Madre Oriental and Sierra Madre Occidental mountains of Mexico, north to southeast Arizona, southwest New Mexico and westernmost Texas, US.
- Unicolored Jay Aphelocoma unicolor – southern Mexico east to Honduras
They live in open pine-oak forests and chaparral scrub habitats.
[edit] Appearance
Aphelocoma jays are slightly larger than the Blue Jay and differ in having a longer tail, slightly shorter, more rounded wings, and no crest on the head. The top of the head, nape, and sides of the head are a rich deep blue. In some species have a white stripe above the eye and dark ear coverts. The breast is also white or grey-white and the back is a grey-brown contrasting with the bright blue tail and wings in most species. One species, Unicolored Jay, is blue all over, superficially similar to the Pinyon Jay from much further north. The bill, legs, and feet are black.
[edit] Behavior
Food is taken both on the ground and in trees. Acorns and pine nuts are the most important foods, making up the great bulk of the diet, with grain, berries and other fruits making up the rest of the vegetable diet. Many insects and other invertebrates are also taken, and eggs and nestlings, small frogs, mice and reptiles.
Wild Aphelocoma jays are frequent visitors at campsites and picnics and have frequently learned to eat from the hands of people where they have become accustomed to being fed.
The nest is in a tree or a bush, sometimes quite low down. The nests are compact and lined with hair and fine roots with an outer diameter of about 30cm to 60cm. Usually 2 to 4 eggs are laid and incubated over 14 to 16 days. There are two main variations of egg shell color: green with olive markings or a paler background of grayish-white to green with red-brown markings. The Florida Scrub Jay and the Mexican Jay both have cooperative breeding systems involving several 'helpers' at each nest, usually siblings of the main pair.
Aphelocoma jays are quite vocal and have a huge range of sounds and calls; common calls include a cheek, cheek, cheek and a guttural churring krr'r'r'r'r. Aphelocoma jays are also, like all other jays, oftentimes quite aggressive at feeding areas, and sometimes regarded as a nuisance.
[edit] References
- Emslie, Steven D. (1996): A fossil Scrub-Jay supports a recent systematic decision. Condor 98(4): 675-680. PDF fulltext
- Ericson, Per G. P.; Jansén, Anna-Lee; Johansson, Ulf S. & Ekman, Jan (2005): Inter-generic relationships of the crows, jays, magpies and allied groups (Aves: Corvidae) based on nucleotide sequence data. Journal of Avian Biology 36: 222-234. PDF fulltext
[edit] Footnotes
- ^ Aphelocoma, from Ancient Greek aphelo-, "smooth" and Latin coma "hair", in reference to the smooth plumage of birds of this genus compared to other corvids.
