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Monday, April 14, 2014

The Sex Life of Crows

By Sharon McInnes

If the title of today’s column made you sit right up and take notice (that was, I admit, my goal), I should warn you that for crows, getting to sex isn’t simple. It involves a lot of planning, preparation, and patience. As Kevin McGowan explained in the webinar “The Secret Life of Crows”, before a crow can land a mate, he has to find a suitable breeding territory. (Scientists call this ‘acquiring breeding status’.) That can be a big job.

American Crow
Photo by Kevin McGowan

Here’s how it works. Let’s say you are, for example, a male crow and you live in the city. Unlike most other species of birds, you could stay home for up to six years, helping to raise your brothers and sisters. Your tasks would include helping with nest-building, feeding, and chasing predators away. (A lot of male crows do this; females tend to leave home much earlier.) Called ‘cooperative breeding’, this strategy is almost as advantageous to your extended family – and to crows in general – as having your own offspring. McGowan says of crows that practice cooperative breeding: “Some of these families are amazing. One marvellously successful crow family lives at St. Catherine’s Church in Ithaca – a breeding pair and up to seven generations of siblings live on or next to the home territory there.

A Family of Crows
Making dinner plans? Discussing a territorial dispute? Gossiping about a neighbour?
Photo by Junior Libby - CC license. 

And there are substantial rewards for staying home to help. One is that you’re more likely to inherit your parents’ territory when they die. In the meantime, they might allow you to use part of their breeding territory to raise your own family. But don’t get excited too quickly. You won’t be getting started in that venture for a while: the average age of initial breeding in McGowan’s study was 4.9 years.

If the ‘one big happy family’ scenario doesn’t turn you on, you have options! One is to find your own territory. Since you live in the city you’ll need about 10 acres. (Country crows tend to have much larger estates.) Of course it needs certain attributes. For one thing, it has to be available. You don’t want to have to battle another crow that’s already set up house there. And it must have plenty of food nearby. (I know – you’re a ‘city crow’ and you’ll eat anything. But your babies need nutritious food – the same kind they’d be getting if you lived in the country.) 

No? Well, if trying to establish your own territory sounds risky, you could join an already established group. This has potential, especially down the road. For example, when the male adult of the mated pair you join dies, you could simply replace him. No need for the widow to go hunting for a new guy when you’re there, ready, willing, and able, right? Or, in another scenario, they might both die, and you could inherit their territory.

Or maybe one of your older siblings has already struck out on his own and would welcome your help?  Or maybe a friendly neighbourhood crow? However be aware that neighbours – especially helpful ones – are known to be philanderers. So if you decide to share the territory of a neighbour, there’s a chance (up to 20 per cent) that at least one of your babies might look more like him than you. Then again, I’d be remiss if I didn’t mention that the same hanky-panky is known to happen between relatives. So you can’t necessarily trust your woman with your brother or cousin or uncle either.  And I hate to even bring this up, but if you and your lady stay together for a few years, and have a few babies, there is a chance that she and one of your sons will get together one night. BUT of all the philandering that goes on amongst crows (scientists refer to this behaviour as ‘extra-pair copulation’) only 3.5 per cent of it is between mother and son. That’s heartening, right?

Still, there’s a good reason for sticking close to home to raise your family: crows that do are more ‘successful breeders’. Compared to robins, for example, which have a 25 per cent nest success rate, the American Crows that McGowan studied had a 60 per cent success rate. Those are pretty good odds, for a bird.

This article was first published in The Flying Shingle ( on April 7 2014

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