Birds in Black: A look at ravens—the world's largest all-black birds.

摘要

I've come to this canyon in the Mojave Desert of California in late spring to get better acquainted with the world's largest songbird. William Boarman, a wildlife biologist with the U.S. Geological Survey, showed me this nest a week earlier. Biologists like Boarman are concerned about the increase in the Mojave Desert's raven population because the birds prey on young desert tortoises, a species the U.S. Fish and Wildlife Service lists as threatened in the Mojave and Colorado Deserts. In other partsof the ravens' range, however, such as in Tennessee and some areas of Europe, the birds have declined so severely they require captive-breeding or translocation programs.