Why We Have Robins in the Cold

Bill Meredith

"You get old and you realize there are no answers, just stories."
            Garrison Keillor, Pontoon, 2008

Cold weather set in early this winter, as one ought to expect. There were only four days last December when the temperatures reported in the Frederick Post were above average, and as I write this in mid-January, we haven't had a day above average yet this year. The freeze line made headlines when it reached Florida, and it seemed to hang on forever; some of the snow from the December 19 storm is still visible in places where the sun doesn't hit directly. To make it worse, we had prolonged high winds that made it seem even chillier than it really was. I felt like I was on Garrison Keillor's radio show, where for the past 35 years the "News from Lake Wobegon" has started out with lines like "It's been cold here in Minnesota, out on the edge or the prairie… last week there were a couple of days it got almost up to freezing, but...."

The truth is, of course, that it really isn't as cold as it used to be. While our local temperatures were below average for the past six weeks, they weren't extreme; only one day in that time span was below 10o F. A lot of my friends, as well as many in the news media, claim they don't believe in global warming, but at the same time they seemed surprised by the cold snap. Part of it is that most of us aren't as tough as we used to be… as a child, I regularly had to chop the ice from the watering trough and lead the livestock out of the barn to drink before leaving for school… and part of it is simply that a lot of us are older.

I avoided the cold this year by staying indoors and working in my shop. I told my wife I was creating useful objects and works of art (the cordless jump-rope I made for her didn't seem to fit either category), but in fact I was mainly producing wood chips and sawdust. The dustbin eventually filled up, so one day I bundled up and waded through the snow to empty it among last fall's leaves in the compost pile. On the way I was stopped by a familiar chirp; and scanning around, I spotted a robin. It was eating crab-apples in a tree by the compost heap.

There was over a foot of snow on the ground at the time and the temperature was in the lower 20s, but I was not surprised to see it. The folklore that robins go south in winter began with the Pilgrims at Plymouth Rock, where it really did get cold in the early 1600s. Biologists in those days recognized that the robin was a member of the Thrush family, and the Latin word for thrush is "Turdis," so they named it Turdis migratorius… "the thrush that migrates." The conventional wisdom handed down to us is that they all go south in the fall, and in New England that is still true; but around here a few of them can almost always be found unless the weather is unusually cold. This is partly because, from the standpoint of New England, we are "the south," but it is also because winters really are getting warmer. Each year, as shown by records such as the annual Christmas Counts, robins extend their range a bit further north.

As I walked back to the shop with the empty dustbin, my mind wandered back to the time when I first began to understand why animals live where they do. It was in 1955, when I was taking my first seminar course in Ecology. The instructor began the course by having several other professors come in and present different models of ecology. This was intimidating… I had never had a seminar before, and was not used to having more than one professor at a time… and it also was also mystifying, for I didn't know what a model was in that context. I was surprised to learn that the word was used to describe a central unifying idea in science, and I was really stunned to be told that there could be many models to explain one particular thing. It was from that one afternoon that I began to understand how science really works… that it involves groping for explanations rather than memorizing facts.

One of the models presented that day was from a new book, The Distribuution and Abundance of Animals, by two Australian ecologists. Ecology, as even I knew at the time, is the study of interactions between living things and the environment. The model said the environment could be understood best by dividing it into four components which must exist within tolerable limits if an animal is to survive. Those components were weather, food, other organisms, and a place in which to live. The conclusion to be drawn was that if you find a particular animal living somewhere, this means it can tolerate all four of those components of the environment; or, if an animal is absent, it must not be able to tolerate one or more of them. I didn't realize it at the time, but this model was to become the central pillar of my doctoral thesis some six years later.

Back in the shop, I could look out of the window at the snow and the crab-apple tree as I resumed the task of making wood chips. I thought of a line from a book by that champion of story-telling, Garrison Keillor: "You get old and you realize there are no answers, just stories." He was partly right: there I was, an old, retired man in a warm place doing nothing of lasting importance, while the robin was out there in a cold place, at work making a living. Then my memory began playing the story, like an ancient tape recording: there were Drs. Schwartz, Taylor, Core, and Baer presenting their ideas, arguing about which was best, and in the process, explaining to me why, 55 years later, I would understand how a robin could be chirping happily in Emmitsburg when it was January and there was a foot of snow on the ground. So Keillor was partly wrong; there was an answer.

Weather is not the problem; birds produce a lot of metabolic heat, and feathers are one of the world's best natural insulating materials. As long as they are kept dry they will protect a bird from 20o temperatures. Survival for a robin depends more on finding food to maintain that metabolic heat; and the food is supplied by another organism, the crab-apple tree. So where there are trees and shrubs that produce winter fruits and berries, birds like robins can survive… provided, of course, that the temperatures are in the range found in Maryland rather than Massachusetts. It wasn't remarkable; it was according to the rules of nature. And those rules apply to humans too.