Sunday, May 15, 2011

Crow behaviour

Last year we were menaced by crows.  Or possibly a single crow.  It or they kept pecking at our windows and we were genuinely worried that it would one day burst through.  We dared not speculate what it might do if it gained access.  Identity theft was a given, but whether it would keep us (barely) alive, writhing in pain for all eternity or kill us outright was not known. 

Eventually it gave up, proving that humans are superior to crows, but in the meantime we researched crow behaviour a little.  Some people said that crows peck windows because they are trying to get at the putty for some reason.  Not true in our case since our windows don’t have putty.  Some said they were pecking at their reflections because they figured it was another crow that needed to be taught a lesson.  This seemed slightly more plausible but not very convincing.  Are crows territorial outside breeding season?  I’ve no idea and didn’t find out.  They have good eyesight and excellent reasoning abilities.  Would their nervous systems be so fooled by a shadowy, pale reflection on a window pane in broad daylight that they’d systematically attack it?  Could be, I’ve no idea.

This year we’ve had only a very few window attacks from what I’m sure is just one crow.  I’ve seen it attacking other windows around the neighbourhood.  But more importantly, I’ve heard it.  I’ve also heard a drumming noise with about the same frequency as window pecks.  It’s a noise that sounds for all the world like a crow pecking on something metallic, like an oil drum or a barbecue or something.  I’m reasonably convinced that this is what’s happening since episodes of drumming are always followed by cawing.  Then in a few minutes, I’ll often hear or see the crow banging on someone’s window.  Then cawing again.

My question is this: might crows attack windows because it makes noise?  Is noise part of territory defence and have some crows learned that they can make more noise or more efficiently make noise by pecking stuff?  Has our crow learned that pecking whatever metal object it is is even more effective?

It’s pure speculation on my part, but it would be really cool if it turns out to be true.  A hell of a lot more fun and satisfying an explanation than instinctive reflection-pecking.

Update: one of the things the crow has been pecking on is next door’s greenhouse roof, which is plastic, corrugated and not very reflective. This suggests that the crow isn’t pecking at it’s own reflection in the mistaken belief that it’s a rival crow. It’s looking more and more like it’s just trying to make noise.

1 comment:

  1. Anonymous5:41 am

    We have had the problem of 2 crows pecking the trellis in the garden, there is ia mirrior behind the trellis, we have tried many ways to stop these two visiting the garden to no avail. My plants on the trellis have been damaged to quite a high degree. We do know they are the same pair as one crow has no tail feathers, this particular crow was in the area last year.