Collateral Gain

It is always fascinating to see that the collateral changes that we get alongside a planned environmental change are invariably unexpected. Ella Davies in the BBC Earth News today reports on the re-introduction of beavers in Poland. Now we have known, from the work of University of Alberta scientists carried out several years ago, that beavers are good for frogs. Beaver ponds are good homes for tadpoles and I’m sure that over a glass of wine in a bar, I would have been rash enough to predict that. But that beavers are good for bats would not have been on my list. I’m sure it was a surprise to the researchers at the University of Gdansk who spotted it.

Of course we have to climb the causal tree to find out why. Water of course is good for insect populations, so that might be it. But, surprise, the bats that hunt over water (such as Daubenton’s bat) aren’t favored. The reason? These bats use the water surface to reflect their hunting sonar to light up insects and the still water of the beaver ponds get a duckweed blanket giving a stealth surface that hides the insects. The favored bats are those that hunt high up among the trees. The thinning of the trees means fewer small branches and twigs making it easier for these species of bat to locate and catch insects.

It is a little over eighteen months since beavers were re-introduced to Knapdale in Scotland, so it is too early to see wildlife synergies, but a fine time to look to see if they develop. The UK’s bat population is in a pretty dire state and an army of beaver conservation volunteers would be a very cheap way to give them a hand up without increasing the tax rate. Also I’m sure that the current citizenship of Inverness wouldn’t do what their 17th century ancestors did – namely to hunt the beavers for their fur and eat their tails as a substitute for fish
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3 Responses so far.

  1. Very interesting! I love Beavers, they are so cute and industrious!

  2. And bats, they're so useful.

  3. jazgal says:

    Just goes to show that you can only begin to imagine how interconnected everything is! Beavers give the nod to bats, but not the ones you'd expect. Everybody has their role, if they get the chance to play it!

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