CACHE-ING IN

Happy boxing day! Supposedly if you’re lucky enough to have servants they get the day off today and you get cold roast beef sandwiches and reheated tea. That sounds like a pretty great tradition to me.

I hope you don’t need the day off because there is work to do and beaver mysteries to ponder. Starting with the mystery of the beaver food cache. Which I realized this week I know less about than I should.

Now this fine illustration by Deborah (the artist who made our bookmarks last year) shows the cache as I i basically imagine it. Leafy branches bedded into the soil, underwater where beavers will have access to it when the water surface freezes. As far as we know our beavers never made a food cache, and had no need to, because Martinez was well out of the freezing zone.

But in following the Port Moody case, where they get a dusting of snow occasionally but the water never freezes, I’ve realized things aren’t entirely clear to me. The city reported that the photo of the beaver in the drain clearly showed it’s “food cache”. But why would a beaver need a food cache where it never freezes? And how would a food cache that’s above the water line be of any use if it did freeze?

Judy says she has watched the beaver sit again next to his pile of sticks and choose which one to eat.  Is this a food cache? Again, why bother if it’s not going to protect the animal from freezing?

There aren’t may photos of food caches online, which I guess means that they are usually underwater or mostly underwater. But I was able to find a few.  I suppose there are beavers in ‘in-between zones’ where it sometimes freezes or has occasionally frozen.

Come to think of it, there’d be zero chance to learn your lesson if you didn’t make a cache when you needed it. Because you’d be dead of starvation and your children would be dead before they could ever learn anything for next year. Maybe since it’s such a high risk situation all beavers keep a food cache?

This is Paul Ramsay’s photo of the beavers at Bamff where it also doesn’t freeze solid. You can clearly see the sticks. Clearly above water. Where it would be absolutely no use to them to have sticks if it did freeze solid. So what’s up with that?

Apparently the cache starts with visible material, then sinks and gets filled in below as the work goes on. In fact it is even suggested that beavers put the good stuff where it won’t freeze,

Well, I can promise there was never a ‘floating raft’ of food anywhere in Martinez. Maybe freezing lightly triggers the behavior? If our beavers had been moved to the sierras would they start caching food?  Research says that when beavers from big rivers are moved to little streams they automatically start building dams, even though they’ve had no practice.

How far from the snowline does a beaver need to be before it doesn’t bother with a food cache? Do beavers  in Jackson make a food cache? In Ione? In Sacramento?

There may be something very specific that triggers caching behavior. It can’t be the presence of ice because by then would be too late in the season to make one. Maybe frost?

I wonder what it is? Think of this as a mystery-in-process, because I don’t have the answers and I very much doubt anybody else does.