I remember that my children and I marveled at the massive numbers of crows roosting in tall trees in the Rockville area of Montgomery County, Maryland in the late 1980s and through the 1990s. Then in the 2000s West Nile virus swept through the county and the trees were empty. The experience left us feeling a real sense of loss. Now I live in the Allegheny Highlands in a rural wooded area. There are crow families around, and we do have several dozen turkey vultures who come in to roost in the tall pine trees each winter. But I have yet to spot a crow roost. I'll have to look harder.