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Will "Gimpy" survive?

Bill Meredith

"The first thing in Science is to know one thing from another."
Carolus Linnaeus, ca. 1757

"If you’ve seen one squirrel, you’ve seen ’em all."
Betty Jean Meredith, 1951 et quia semper

(March, 2015) I never had a course in Journalism, but I could not have written monthly articles for the past 17 years without learning a few of the basic rules. The one I am grappling with just now is that short months have early deadlines. February is a short month, and it ends on a weekend this year, so my deadline for writing came earlier than usual. As it happened, it was the 12th of the month when I first sat down at the computer to begin arranging whatever ideas I could conjure up into a first draft of the March article. And for what seemed like several hours, nothing happened. Then I noticed that it was Abraham Lincoln’s birthday; and, as everyone knows, Charles Darwin was born the same day and year. So, I had a topic.

Darwin was not the first person to come up with the idea of evolution; it goes back to Greek thinkers as early as 600 BC, and is found among Chinese writings of similar antiquity. The Greeks believed humans were descended from creatures that lived in the sea, but they thought those creatures were literally half human and half fish; this was consistent with the tales told by sailors, who reported seeing mermaids and sirens, like those who tried to lure Ulysses’ ships onto rocky shoals in The Odyssey.

By the 18th Century, miners and canal-builders began to find more and more strange-looking fossils, but it didn’t occur to most of them that they were related to present-day creatures; even Linnaeus, who classified and gave Latin names to over 6,000 species of animals, did not believe they descended from earlier forms. But a few scientists were beginning to suggest that animals like wooly mammoths found frozen in Siberia could have been the forerunners of elephants, and by 1800 several people were wondering if dinosaurs were forerunners of modern reptiles. So Darwin didn’t "invent" the idea of evolution. What he did was to propose a feasible theory to explain how it worked. The central part of that theory was "Survival of the Fittest."

I saw an example of how survival works last month when a flock of several hundred cowbirds descended on my yard after a snowstorm. For a few days they stayed and ate everything in sight; then they moved on, as their ancestors have done for thousands of years. At first, I could only distinguish the sexes… females and juveniles were uniformly gray all over, but adult males had solid black bodies and brown heads. They were a spectacular sight, and my wife even came to the window and watched them for a few minutes; however, she soon remarked that "If you’ve seen one cowbird, you’ve seem them all," and went on to greater things.

Being less ambitious, I stayed and watched for a long time; and I soon noticed that a number of individuals were not as healthy as the rest of the flock. And surely, if my fading eyesight could pick out the less vigorous individuals, they would stand out to a passing hawk; I’ve read that hawks can see a dime from a distance of 100 yards, and their lives depend on picking out the most vulnerable prey. If a hawk (or any other predator) came along, most of the cowbirds would be strong and alert enough to escape; but the sick, old or injured would be for lunch. Survival of the Fittest was ready to happen right there in my yard.

Survival is an odd thing to think about; how you respond to it depends on the example you’re looking at. Josef Stalin said one death may be a tragedy but a million deaths are a statistic, and that’s how I felt about the cowbirds. There were hundreds of them; if half a dozen die, who will miss them? But if the one that dies is known to you as an individual, you react differently.

On an ordinary day, I see 15 or 20 species of birds at my feeder. In most cases, there are only a few of each kind, and I can’t distinguish one individual from another; but there are exceptions. Several years ago there was a junco that had only one leg; it was healthy and got around very well, except that it had trouble standing up in new, soft snow. The grandchildren were small then, and we called it "Short John Silver;" we could recognize it at a glance, and watched for it every day. It survived the winter and left for the nesting grounds in the North Woods when all the other juncos did. Another year, we had a robin with three white feathers in its tail; it stayed all summer, and raised two broods of chicks. Over the years there have been many cases like these; one individual may be recognized by an injury or a "birthmark," but all the others look alike. Right now there is a male goldfinch that has started to molt early; he has a few yellow feathers on his shoulders, instead of the usual winter’s olive drab. But there’s no use giving him a name; in a few more weeks, all of his band of brothers will look like that.

Two summers ago, a pair of gray squirrels raised a family in the Great Forest behind our house. Both parents carried a mutation in the genes that determine color, and they produced at least four black offspring. The young ones showed up at the bird feeder that fall; two of them are still surviving. They are like identical twins; you can recognize them but you can’t tell them apart. They come nearly every day, along with six or seven of their gray cousins, who all look alike… except "Gimpy."

Gimpy was a normal teenage squirrel when he arrived at the feeder last fall, but in an outburst of testosterone-inspired machismo, he challenged an adult male and was severely mauled. One ear was nearly bitten off; some of the tendons that enabled him to move his tail were severed; his right front foot was probably broken; and a large chunk of skin was torn off his left hind leg. He was lucky that he wasn’t killed; young males sometimes are. Fortunately, the injuries to his legs were on opposite sides of the body; had they both been on the same side, he wouldn’t have been able to climb, and an injured squirrel on the ground is a Dead Man Walking. It was touch and go for a week, but the really cold weather hadn’t arrived yet, and he began to mend. But he was a slow learner; a couple of weeks ago he showed up bleeding from a large gash that exposed muscle and sinew on his back.

Gimpy’s latest injuries have started to heal, but the future doesn’t look bright for him. He hobbles around dragging his tail through puddles where the snow has melted. It’s not just a matter of looks; a squirrel’s tail is more important for survival than one might think. We learned in school that cats and squirrels use their tails for balance when climbing and jumping; but with squirrels, the tail may be even more important as a means of communication. Male squirrels court females by raising their tail and waving the tip of it forward and backward. Whenever two males meet, the tail is used to signal dominance or submission; if the low-ranking male lowers his tail and retreats, a fight is avoided. In Gimpy’s case, since he can’t lift his tail, he is less likely to be attacked… provided that he has learned his lesson and remembers not to advance.

So far, he has; but it remains to be seen what he will do when the days get a bit longer and the females become amorous. Gimpy may not die from his injuries, but the chances that he will mate successfully and produce offspring to carry his genes into the next generation are significantly lower. In a Darwinian sense, he will not be a success.

Read other articles by Bill Meredith