the open desert cannot support a large population of ravevens, and survival can be a constant challengnge. food anand water ae scarce, and finding them is a fufull-time job. b but thankno man, that is changing. man: the raven is a very widespread bird in north america and has always been present in low numbers, even in the deserts. and what's happened lately is thahat human incucurss into t the desert have brought additional food and water. and their densities have increased as a result of those extra resources. [ravens squawking] narrator: whether picking up crumbs at a highway rest stop or dumpster d diving behind a restaurant, ravens have come to associate people with food and water. william boarman: there is somewhere between 2 and 15 times the number of ravens at important resource sites, like landfills, sewage ponds, and towns, compared to the open d desert. narrator: now there are so many more ravens that they have moved aggressively into areas that were mostly off-limits. and there they are disrupting the ecosystem. there are 4 major deserts in north america. in the united states,