At this time of year, an incredible sight to behold around sunset on the Nantucket Conservation Foundation’s South Pastures Property is murder! A murder of American Crows, that is!
Whether you consider yourself a birder or not, most people recognize a crow when they see one. American crows (Corvus brachyrhynchos) are large, shiny black, and quite raucous birds. They can be found throughout much of the United States and Canada except for the desert southwest. Crows are closely related to ravens, jays and magpies. Very unfortunately, they have developed a reputation as being harbingers of evil due to the poetic use of the term “murder” in reference to large flocks of crows, their presence as ill-omens in Chinese, German and Greek proverbs, their propensity for eating carrion, an association with battlefields and cemeteries, and of course, their infamous depiction in Hitchcock’s “The Birds”.
In reality, crows are highly intelligent and exceptionally social creatures. They spend most of their long lives as part of tightly knit family groups. Young birds will remain with their parents for 2-4 years and help to raise young, defend territories and find food. Crows are known to problem solve in groups, and to make and use tools. Despite the frequent assumption that crows are only “death eaters”, carrion actually comprises a small percent of their diet. Crows are actually quite omnivorous, eating everything from fruits and nuts, to worms, insects, fish, snakes, small turtles, and yes, garbage and road kill.
Perhaps because of their social nature, crows are particularly susceptible to West Nile Virus. This virus has a nearly 100% kill rate in crows and they typically die within a week of contraction. While populations have suffered declines due to the virus, it is believed that their numbers are still great enough that worry is not warranted – they are still listed as a species of least concern by the IUCN.
In the winter, American crows sleep in communal roosts that can number in the thousands and even millions! Here on Nantucket, go for a sunset walk along New South Road, west of the Tom Nevers ball fields – you may be lucky enough to witness this amazing spectacle! Hundreds of crows can be seen (and heard!) circling overhead and roosting in the scrub oaks on both sides of the road. Before settling down for the night with the main flock, a few nights ago I watched small group of crows harassing a snowy owl who seemed to be minding his own business. This behavior, referred to as mobbing, is common with crows – they are known to aggressively defend their groups and territories from perceived threats.
Despite superstitions, there is no reason to suspect or fear crows. They are intelligent and inquisitive birds that are fascinating to watch. Happy Birding!