Both Black and Turkey Vultures are migratory throughout most of their range. They are primarily scavengers, although they can (and ocasionally do) capture and kill live prey where the prey species is/are abundant.
I live about 15 or so miles east of the Arizona line, at 4,400 ft elevation in the Animas Valley of southwestern New Mexico. Here, in the overlap of the Chihuahuan and Sonoran deserts, we see lots of Turkey Vultures passing through, both spring and fall. However, both Bald and Golden Eagles winter here, too--and they subsist primarily on road kill and other carrion. They are much more aggressive than the Turkey Vultures which seem to just move on south once the eagles arrive. The Black Vultures are strictly occasional summertime visitors. Additionally, both vultures have circulatory systems that are not especially efficient at regulating body temperatures. They don't do well around here where winter nights are often close to (or below) freezing. It takes them a while to warm up in on sunny mornings after a cold night. Periods of frequent cloud cover during cold days seems to spur them to move on south.
I suspect that you are just not in a major migration corridor, but local availability of prey and carrion probably also play a part.
Last edited by mudhen; 03/11/20.
