Every evening at dusk, huge numbers of crows begin to swoop and soar as they move south though Bolton Hill airspace. From our porch (perch) on Bolton Street, they appear to be moving south between Eutaw Place and Mason Street, making brief stops on the tall trees and roofs before making their final way to communal roosting spots south of Bolton Hill. At dawn, the crows leave their roosts in mass and return north to feed, waking up sleeping humans with their caws.
American crows are fascinating creatures. Part of the genus Corvus, crows are incredibly smart, with a high brain-to-body size ratio, the highest of any bird (and higher than humans). Crows can create and employ tools to obtain food, have “funerals” for fellow dead crows, can recognize and terrorize people who threaten them, and can cache food and leave identifying marks to locate and retrieve later. They are omnivorous and feed on seeds, trash, and carrion, preferring open areas to forage for food. They even employ sentinel crows on high outposts to warn them of predators when they are on the ground scavenging.
But what is up with crows’ movements before dusk and at dawn?
Crows are communal creatures. From fall through spring, crows who are resident in Baltimore or have migrated south from their nesting areas, gather in small teams at dusk after foraging during the day and before streaming towards their communal roosts for the night. Some crows will travel miles to join the communal roosts. Early on Nov. 2, I observed what I presumed is a communal roost on the building at State Center on Martin Luther King, Jr. and Eutaw Streets.
Crows roost together for several reasons. First, the communal roost provides more eyes and ears to protect them from predators (owls and hawks) who hunt at night. Second, communal roosts provide protection against the cold through the body heat of the flock. Third, communal roosts allow for crows to communicate with each other, presumably to share the location of food supplies and potential predators. Crows are increasingly drawn to urban areas because roosting in areas lit with artificial light provides extra protection from predators, who avoid these areas. By spring, crows move off to other nesting grounds.
Bolton Hill seems to be a flyway, not a roosting spot. However, in October 2022, residents of Mt. Vernon were plagued by a communal roost of crows in the trees surrounding the Washington Monument. The situation was noisy and messy. It was featured on NPR. The recommendation from Science Friday experts was to hire a falconer to discourage the crows from nesting in the area.
But, by March 2023 the president of the Maryland Center of History and Culture, Katie Caljean, reported to WJZ TV news that “Crows don’t like the sound of predators. So, we’re playing owl and hawk sounds to spook them each morning and evening and they haven’t come back!” Bolton Hill may have to consider these measures if the crows roost in our neighborhood. Until then, we can enjoy watching the nightly flights of crows as they move to their roosts and imagine their conversations as they discuss the next day’s prospects.
–Sallye Perrin
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