A Murder of Crows
Have you ever found yourself ducking under a dark blanket of crows at dusk? Or flying in a singular direction towards Still Creek between Gilmore and Willingdon Avenue? If so, you will have experienced a Murder of Crows in constant theatre of movement and raucous sound.
Every afternoon, near dusk, thousands of crows across Vancouver, Burnaby, the North Shore, and beyond, uproot themselves from their daily urban foraging to migrate back to their evening roost along Still Creek. For years crows have been flocking nightly to this location in groups. They are part of a large extended family that gathers to chatter and feud over the best perch, the daily catch, or the latest evolutionary trick.
The Roost
Crows have been gathering in large winter roosts for as long as people have been around to witness them. Research has revealed that large populations of rural crows are migrating to urban areas. Possible reasons may be the urban “heat island” effect (urban areas radiate more heat into the atmosphere than the surrounding countryside); artificial lighting that helps crows watch for preying owls; and the presence of protected stands of trees in urban areas that make ideal crow roosts near food sources.
Although some of us are impressed by the strength of historical instinct, and the visual impact of night flight, others experience the negative impacts of noise and guano on residences and businesses. Some have installed distress call devices to disturb and scatter the crows. During your visit you may hear the false cry of a red-tailed hawk, or you may see a fake owl perched on the edge of a building. These devices and the removal of roost trees can create a change in Roost location, but so far there hasn’t been a dramatic shift from their home Roost here in Burnaby. If the trees are gone, the crafty crows will perch on poles and wires.
Crows
The American and Northwestern crow are part of a large family of birds known as corvids. Although many think of crows as nuisance birds, they are good citizens of their ecosystem. Their habit of eating carrion makes them part of nature’s cleanup crew. Crows are considered to be among the most intelligent and social of all birds. They cooperate to find food, raise young, and defend themselves. They tend to mate for life, and their offspring may spend up to six years helping to care for subsequent nestlings. Scientists have observed them making tools to collect and eat food. Crows also plan ahead, hiding food for later consumption. These clever birds may even work together to mob a threatening predator, or another crow attempting to move in on the group’s territory.
For more information on crows and ravens see:
John M. Marzluff and Tony Angell. 2005. In the Company of Crows and Ravens. Yale University Press.
**Congrats** to geodug and _CB_ for their FTF crafty ways!!!