Note: Most of these answers pertain to the American Crow, _Corvus brachyrhynchos_. Much of the information here is from my own research on crows in central New York; where I used other sources I have tried to reference the material. —Dr. Kevin J. McGowan, Cornell Lab of Ornithology.

Thousands of crows flock to Portland's park blocks each winter, darkening the sky at dusk and roosting overnight in the city's trees. Much about the crows' habits is unknown.