Because the beaver isn't just an animal; it's an ecosystem!

The Martinez Beavers

Beaver Druthers

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Recently I received an email from Dr. Duncan Halley. a researcher in Norway who is very interested in beavers. He’s the author of several papers on beaver population settlement.  Duncan was the scientist on the recent beaver fieldtrip in Scotland teaching anglers about how and why to live with beavers. One of the facts he reported was that beavers ‘prefer to be in large bodies of water’ where they don’t need to build dams. I scratched my head at this and asked him to explain his thinking. He wrote back,

Left to themselves beavers prefer to settle where damming isn’t necessary; but of course, especially later in the process of population development, all those places will be taken. It’s a bit like the first farmers in a district using the fertile valleys, and some of their grandchildren opening up the stony hillslopes – not because they prefer them, but because you can make a living there and that’s all that’s left.

Now mind you, he’s talking about Castor Fiber, not Castor Canadensis. But I’m not sure the behavior would be that different because of 2 genes. What makes me curious about this is whether a big body of water like the Carquinez Strait is really a better place to be a beaver than our cozy Alhambra Creek. Did our beavers ‘settle’ for this habitat because there were too many beavers in the big water to make a living? How would something like the strait (which the Benicia Bridge passes over) ever be ‘too full’ of beavers? I suppose the banks could run out of food, but we know our beavers go into the strait every night to feed, so doesn’t that mean there’s more food in the Strait than there is in the creek?

I like Duncan very much and am very interested in his research. But I’m going to have to say I consider this observation ‘suspect’ and not supported by what we’ve seen over the last 6 years. Since the Carquinez Strait is not ‘thick’ with beavers, I have to think that our beavers settled in Alhambra Creek because they wanted to, not because they had too. If anything the behaviors we have seen suggest that beavers prefer small damable creeks where it’s easier to mark their territory and protect a family. They settle for large bodies of water when that’s not possible. I’ve always thought it was kind of like the difference between being adopted by a family or staying in a large orphanage.

I can’t even imagine how we could design a study to figure this out. Can you?

How beavers plug pipes - Cheryl Reynolds
How beavers plug pipes – Cheryl Reynolds