Published: September 13, 2019

By Mark Seth Lender

A big pronghorn buck coolly stands his ground. (Photo: Mark Seth Lender)

Living on Earth's Explorer in Residence Mark Seth Lender remarks on the ramifications of relative size when it comes to staying warm in cold climes -- and staying cool in the presence of an intimidating animal.

Head north, the wildlife is bigger. Same species. Different volume. Bulk is a protection against cold and the energy requirements imposed by cold. A simple way to understand this is to consider the inverse. If you live above, say, 400 north latitude or high enough above sea level, then you know about the glaze that forms on the surface of a window pane overnight and melts rapidly at the slight increase in heat that shines from the winter rising sun. While block ice will last all day and then some, even in summer. In the abstract, as surface area increases relative to mass, thermal exchange increases. And vice-versa. To exist in cold climes animals must stay warm. An animal with more heft and thickness and less surface area can better hold heat and thus maintain body temperature at a lower caloric burn. All this I knew. But when you see it, and the impression moves from abstraction to physical fact, it is a different kind of knowing.

And there are other ramifications. Big animals completely understand how big they are. I expected the pronghorn to run. But I was measuring that response against a much lighter-weight version of pronghorn. The resident male probably felt that way about me. That I should run. I just wasn’t smart enough to see it. Not that running would be any good if he decided I was a real and true threat.

Because of his confidence, it was the closest I have ever been to pronghorn antelope.

Listen to Mark Seth Lender read his Pronghorn Antelope essay

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