RAVENous for crow eggs 

Given their similarities, it might surprise folks to see crows occasionally harassing and chasing ravens. After all, birds of a feather right? Not in this case.  Rather than being in cahoots, the relationship between crows and ravens is most often competitive, though it can also be predatory.

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A raven barrel rolls to scold an attacking crow.

Such is the case in a recent video shared with me by a reader, Ty Lieberman.  To the dismay of him and his colleagues, a crow nest they had been observing outside their Los Angeles office window was partially dismantled, and at least one egg taken by what they believed was a pair of crows.   Concerned for the survival of the nest, Ty reached out for my interpretation.  Based on his initial description, I wondered if maybe he had witnessed egg transport, something I knew had been observed in black-billed magpies and pinon jays.1  Previous accounts of these species included descriptions of eggs being taken, and then returned to the nest, as well as eggs being deposited into the nests of neighbors, both of which are utterly fascinating behaviors and probably warrant their own post.

To date, however, there are no accounts of crows engaging in this behavior, though there is one documented observation of a nestling being deposited into a nest from which it did not originate.2  Again, utterly fascinating, but not helpful here.

Later, a more detailed account from Ty made mention of the size of the intruding birds, which quickly led me to the story’s true explanation.  Shortly after my ‘ah ha’ moment, to the dismay of he and his colleagues the nest raiders returned, and this time were caught on video by one of Ty’s colleagues (who you can follow on twitter, @namnam).  Rather than being crows, these literal homewreckers were common ravens.

Instead of being something out of the ordinary, Ty had witnessed a typical breeding season interaction between crows and ravens.  It’s no wonder then, that crows can be so hostilie when ravens enter their territory. 

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Crows (top) mobbing a raven (bottom) in Kent, WA

Eggs of all kinds are one of the most power-packed meals in the animal kingdom, so it’s no surprise ravens would take advantage of crow nests when they find them.  Around this same time back in 2015, a black bear made a similarly memorable meal out of a raven nest, reminding us that for corvids of all kinds, it’s a constant fight between being predator or prey.

Literature cited

  1.  Trost CH and CL Webb. 1986. Egg moving by two species of corvid. Animal Behaviour 34: 294-295.
  2. Schaefer JM and Dinsmore JJ.  1992.  Movement of a nestling between American crow nests.  The Wilson Bulletin 104: 185-187

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Filed under Birding, Breeding, Crow behavior, Raven behavior

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