Aphelocoma - Behavior

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 30 cm to 60 cm. 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 relatives of the breeding pair.

Increased prolactin in the breeding pair leads to the expression of parental behavior and physiology (Brown and Vleck,1998 ). The source of the alloparental behavior found in helper birds has been the focus of many studies. Recently, a positive correlation between increased prolactin levels during the breeding period and helping behavior in non-breeding Aphelocoma jays was found (Brown and Vleck, 1998 ). This suggests that helper birds do not simply respond to the calls of the young, but begin to shown parental behavior even before the chicks hatch. These data suggest that natural selection may be acting on in Aphelocoma jays and New World jays in general because the birds are reacting to more than just an environmental stimulus. Studies have also been done on Florida Scrub Jays (Aphelocoma coerulescens) and results have confirmed the hypothesis that increased prolactin levels are correlated with an increase in parental behavior in helper birds (Schoech, 1998 ).

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, often quite aggressive, and antagonistic at feeding areas, and sometimes regarded as a nuisance.