EPOW - Ecology Picture of the Week

Under the Snow

Crater Lake, Oregon

Explanation:  This was a particularly spectacular snowfall, here on the high-elevation rim of Crater Lake in southern Oregon.  Snow was flocked to roofs and trees, and to bare branches and dense foliage, and piled high.  

Yet, there is life under the snow.  It is well known that wildlife species such as forest mice, shrews, and voles, and even some spiders, beetles, and other invertebrates, can move and tunnel and forage in the space between snow and ground.

This interface area is called the subnivian space, formed as a pocket of air at ground surface, protected from harsh winds and deeper cold by the layer of protective snow.  

Some predators, including some owls and red foxes, have learned to hunt for subnivian prey by using extraordinary hearing to zero-in on the sounds of small mammals tunneling, chewing, scampering, and digging beneath the snow.  

But the question posed this week is, are there equivalent subnivian spaces on above-ground vertical surfaces ... such as trunks of trees and sides of buildings?  What animals might persist and use such protected subnivian spaces there?   

Snow layers on plant foliage could help insulate growing tips, buds, and twigs from extreme frost damage, yes, but what else is going on under that layer that we cannot see?  Do tree-dwelling mammals use such snow cover to escape predators and keep warmer?  What biological processes persist under the snow -- way above ground level?