Mobbing of owl by a murder of crows

posted in: Interspecific | 1

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Ann Stewart lives in Lacey, WA, USA, near to the Nisqually Wildlife Sanctuary. Recently her residential area was “shaved of its beautiful Doug fir forest, so some animals have moved into the neighborhood. However, owls were here before that, I assume because yards are open ground for spotting mice, cats, etc. (I don’t know that they’ve actually grabbed any cats, though). I don’t know what kind of owls they are.

On 5th June 2007, after reading the post on Mobbing of a Barn Owl, Ann further wrote:

“I didn’t know about mobbing until today.

“Around noon, suddenly out of the southern sky a huge murder of crows (at least 100) came at my house, bent on attacking something in a tall Douglas fir. Although the fir had been stripped of branches lower down, the crown was dense, so I couldn’t see what they were after.

“I’ve heard owls in those trees before, and now that I’ve done some research on the Web, I’m tentatively concluding that this murder was after an owl. We also have hawks, bald eagles, and raccoons. I don’t know whether raccoons can climb that high (I do know that raccoons on the other side of town have taken up killing and eating cats and small dogs, not that that’s relevant to this comment, but maybe all the woodland denizens have gone mad as the builders have rapidly taken away their habitat).

“They circled and attacked one spot in the tree over and over again for about 30 minutes. Then they all flew off (I wasn’t watching – you can’t see the crown of that tree from inside my house and I was afraid to go outside, as were my cats. I heard them fly away (the crows, not my cats). They scared me, and I had assumed that they killed whatever they were after.

“A couple of days ago I found a dead crow at the foot of that tree. Today after all the crows had left, I found another two dead crows. I’m curious whether the murder was trying to kill the owl or tell it to leave their roosting place alone or getting even for the first dead crow. And the two recently departed – could they have been accidentally killed by their manic compadres, or could an owl under attack have managed to kill them? What do you think?”

My answer: “Many songbirds mob owls when they encounter them during the day roosting in a tree. Most of these mobbing birds are no match for the owls, risking their lives doing so. Yet they continue to mob the latter, chasing them away from their roosting sites. Once mobbing starts, other birds usually join in. Most of the time the owls simply leave without putting up a fight. Too many mobbing birds to deal with? Crows, larger and more aggressive than most songbirds, can be a serious challenge to a lone owl, if there are many of them. Their main aim is to chase the owl away.”

On 08 Jun 2007 Ann Stewart replied: “Thanks for answering my questions. I wish I could climb up in that tree to see if there’s an owl nest there & whether the owl left for good or is still there — or would I be courting an eye-gouging? Anyway, the tree is a full grown Doug fir, and the only way I’d be able to get up it is if I had a pair of telephone lineman spikes. I’ve tried to look up in the tree but the branches/needles are too thick up there for me to see anything definitive. If I had the nerve to get up on my house (2-storey), I might be able to see something, but I’m pretty sure that’s suicidal.”

Note: Crows live in a group called a murder. This is a fanciful usage for a group of crows. However, most people, especially ornithologists, may use the more generic term flock or horde.

In the absence of an image of Douglas Fir (Pseudotsega menziesii), I have added one of Nordmann Fir (Abies nordmanniana) just to give an idea of the size.

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One Response

  1. Ron Chesney

    It is quite possible that the crows were ‘at war’ with rivals. At present I am watching crows frenetically chasing others around the skies in what looks like territorial rights. This apparently takes place as Autumn sets in and the weather becomes colder.

    I wonder what is at the top of the tree!

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