May – June is the peak fledging period for crows in our area — it will change slightly for different areas. World-wide crow chicks that are a week short of flying are getting too big for their nests and begin to walk – run along the branches from their nest, getting exercise. They are world-wide called branchers. Their flight feathers are not fully grown and they are confined to this branch. More importantly they are also exposed to passing eagles who sense a vulnerable prey. I have many times seen the eagles, sub adults and adults swoop in and try and knock the immature crows from their branch and scoop them up as they flutter off the branch. The eagle-crow conflict that dominates these species interactions for the rest of their lives is here rooted.
If the young crows evade the patrolling eagles for this week they can readily outfly their huge long-winged adversary and enjoy pestering eagles for the rest of their life.
Because we have had an unusual incident of the White Rock eagles bringing in a live crow chick to the nest and it surviving a couple of days this topic got unusual coverage. However, eagle predation on young branching crows is a very common annual event. At least it is here on the northwest coast. The amount of questions I got this year makes me wonder if other areas, particularly where there are CAMs also get to annually witness this same temporary brief predation. I would love to know if other areas get to experience this same week of vulnerability of crows?
What made me respond with the note was one of our regulars suggesting if this ‘unusual’ behavior was a shift to a crow diet due to a lack of fish! Neat idea but – not quite my experience. All my life I have been aware of this vulnerable week in the life of young crows. The last 15 years of live streaming CAMS brought this behavior to an annual visual reality. Most often a little crow, weighing probably less than 100 grams or about 5 to 6 ounces is eaten before the eagle returns to the nest so the frequency of young crows is not as obvious. This I find challenging as crows and ravens are two of my favorite birds — along with eagles, cranes, ducks, geese, hummingbirds etc. etc.