American Crow responses to habitat desaturation by West Nile virus

In late Summer 2002, West Nile virus spread to a population of individually-marked, cooperatively-breeding American Crows ( Corvus brachyrhynchos brachyrhynchos ) in Stillwater, OK. Within six weeks, approximately 42% of adults were dead, leaving widows, widowers, and vacant territories. I looked to see if surviving unpaired adult crows left groups to occupy vacant territories, as predicted by theory (Habitat Saturation/Ecological Constraints Hypothesis; Emlen 1982, 1984). Survivors did not behave as predicted, had previous decisions to delay breeding and live in others’ groups been made in response to a saturated habitat. Their aberrant behavior and physical attitudes suggested their losses and grief affected them in ways not included in simplistic models of avian behavior.