If you've been hiking in the Rockies this summer, you've probably noticed something: the evergreens are loaded with cones. The subalpine fir and the Engelmann spruce in the higher parts of Banff and Yoho parks are covered with cones, and in our twenty plus years here, this is only the second time we've seen this.
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| Bumper crop of subalpine fir cones ripening in mid-August |
It's called “masting”, and has been observed in other tree species around the world. Biologists think that when big mast years, like this one, are paired up against years of almost no cone production, then predators of cones – like squirrels – can never reach a consistent population level where they can eat all the seeds in all the cones.
It's the trees' defence system: starve the squirrels one year, and overwhelm them with food the next. It guarantees that some of the seeds in the cones will get to the ground to germinate, which is what the trees want.
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| Fir cones shedding their seeds last week. |
The big question is, “how do the trees do it?” How do they synchronize, between individuals and across species, the big mast years and the years of low cone production? We haven't been able to find the answer, but if anybody out there knows, we'd love to hear about it.
In the meantime, you can enjoy the crop through photography, and you can watch the red squirrels in their collecting frenzy. In the last couple of weeks, we've been beaned in the head by cones that the squirrels are throwing down to the ground to collect for winter.
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| Cones clipped by squirrels for winter storage. |
