Winter World_ The Ingenuity of Animal Survival - Bernd Heinrich [127]
In early January 1995, I thought I was finally getting close to tracking them to a sleeping place. I had noticed a group of three of them in the spruces near my cabin, and on January 5 I saw them again and followed them for eighty minutes. Finally, as it was getting dark, I heard them make some persistent soft tsees, then many louder ones, and then, at 4:20 P.M., the birds suddenly became quiet and vanished from sight. But it was just getting too dark to see. The next evening I waited near the same area till 4:30 P.M., and saw nothing. A student, Jeremy Cohen, took over near the same site the next three evenings, and he managed to follow a (or the) group of three kinglets on one evening, again until 4:30 P.M. when it was almost dark. None had entered the three local red squirrel nests that I had located near there previously. At dawn the following day, I arrived with Cohen and other trackers at the same site where they had been last seen on the evening before, and we did indeed see three birds just as it was getting light. But it was not near a squirrel nest. I then became ever more doubtful that the kinglets’ key to winter survival in the Maine woods could be traced to squirrel nests.
I also doubted that kinglets would routinely burrow into the snow on the ground and dig tunnels like grouse do. That is because I’ve frequently encountered rainstorms followed by icing that produced thick crust on the snow. Only a large strong bird can escape the icy prison, or last it out till the ice melts. It seemed possible, however, that kinglets could burrow into the undersides of snow cushions on branches, and in that case they could again escape from below, because the ice crust forms only on top.
In the winter of 2000–2001, I and my Winter Ecology students again made it one of our projects to try to pursue kinglets to their sleeping quarters. Again we were unsuccessful in tracing any birds into a squirrel nest. Nevertheless, we probably got closer than ever before to what they actually do. It was by accident.
Two kinglets fluffed out and huddling in a snow cave on a branch.
On December 19, one of the students, Willard Morgan, went out before sunrise to enter a hiding shelter we had built out of brush to watch ravens (where they could not watch him) arriving at a carcass. On his way to that shelter, while walking in the semidarkness, he flushed two kinglets almost off the ground at his feet from under a brush pile he passed. The brush was covered with cushions of freshly fallen snow. The previous night had been windy and blustery, with sleet and snow. Being close to the ground and tucked under the snow cushions in the brush pile, the kinglets would have escaped the weather. Morgan returned to the same site to watch in the next two evenings, but the kinglets did not return. This observation strengthens my suspicion that kinglets, in order to forage to the last minute of the day, are forced to use any of a variety of shelters, not only that in or under a squirrel nest. If so, their behavior places ever more burden on both deep nocturnal torpor and simultaneously the necessity of shivering all the night long.
The cheechako, in Jack London’s story “To Build a Fire,” died in the Alaskan winter not because he made one big mistake. He was just unlucky and also made tiny errors that accumulated and amplified, until they made all the difference. I conclude that the kinglet similarly, but oppositely, has no magic key for survival in the cold winter world of snow and ice. Those that live there are lucky and do every little thing just right. The odds of surviving the winter are slim, but the gamble, as in the breaking of the buds and the winter hive exits of the bees, has risks that must be taken. The unlucky rolls of the dice that result in individual deaths