When you see them gathered by the thousands, blackening treetops for blocks, it is no wonder that crows were given such a ominous group-noun, a murder.
Like a growing proportion of humans, crows thrive in urban environments. A Nature of Things episode offers lots of fascinating insights about the parallel lives that crows and humans lead: Just like people, crows like open spaces with a few trees, they can eat just about anything we do, and they have an impressive capacity for learning and passing knowledge to their peers and their young. This capacity for cultural evolution (passing learned knowledge on from one generation to another) means that they can quickly adapt to the complexities of the city, as was proven when they were shown to navigate traffic signals.
But the documentary gives no inkling of why crows sometimes gather in the thousands or tens of thousands. A Cornell university ornithologist writes that these large gatherings are poorly understood by scientists but may be a defence against predators, an occasion to exchange information, or simply gathering around a known food source. The author also suggests that crows like to roost near artificial light sources as a defence against predators such as owls.
Zoologist-photographer Tristan Brand, who snapped this photo just before Christmas, hypothesized that the crows were fleeing a storm front on the East coast.
One comment
I’ve never seen such a murder in Montreal before. We don’t even seem to get that many crows in the Plateau.
(also the picture has a link in it, but it goes to an error page.)