The worst of winter should be about over, with March just around the corner as I write this week – or so some might think. For many kinds of wildlife and even some people, the worst is yet to come. The most sought-after foods that many wild creatures depend on are about gone. Historically, those foods would have included a variety of nuts like white and bur oak acorns (red oak acorns are too bitter), hickory, hazelnuts, walnuts and chestnuts. Dried berries and fruits of several kinds would also have been eaten. They’d also have consumed grubs and insect larvae dug out of rotten logs or stumps and insects wintering over under loose tree bark. Predators would have depended on prey animals of many kinds, but mice provided a good bit of nutrition for most predators; even larger ones. Good food gets harder and harder to find by late winter. Some wildlife can supplement native foods with waste grain today, but many species can’t eat corn. It will be months before new growth and reproduction can again provide enough food. It was a hard time of the year for Native Americans and our pioneer ancestors, too. Foods stored away in the fall would be running low and might soon be gone. Rations were often pretty thin — trying to stretch what was left until spring. They called this time “the hunger moon.”
We go to the store today and keep eating like we do the rest of the year. Many of our wild neighbors have to resort to other means of surviving the winter. Some hibernate by drastically slowing their metabolic rate and lowering their body temperature to just above freezing in order to live all winter on stored fat. Woodchucks and some ground squirrels are good examples of true hibernators. Early warm spells (before real spring) can break their slumber and lead to starvation. Others estivate by laying low and conserving energy during the worst times, when weather is too harsh to go out to search for more food. Many kinds of winter wildlife use some form of estivation, including coons, skunks and opossums. Some humans seem to do that all winter long! Yet other birds and animals migrate to where they can still find their preferred foods. Some may move only a few hundred miles, but others may fly thousands of miles to the southern hemisphere, only to turn around and do it all over again in the spring. Many of our winter birds go into a kind of mini-hibernation called torpor every night, only to crank their amazing metabolism back up to full speed every morning. Many have to shift their diets to less desirable foods
There are always exceptions. Most robins and bluebirds migrate in order to continue finding their preferred foods. A few tough it out each winter and find ways to survive without migrating. “My bluebirds” appear to be in that group this winter. I have seen them visiting “their house” in my back yard at least once a month, but they probably have to wander quite widely to find enough food. The male and female spent some time in the yard again on Feb. 23. Some of their youngsters from last summer were still with them when they were here around Christmas. The male showed that he was ready to defend his home during his most recent visit by chasing away an English sparrow. His message was clear: “Don’t even think of trying to move into my house!”
Wintering robins and bluebirds have to shift their diet from mostly animal foods (earthworms and insects) to plant-based foods. Dried berries are a staple if they can still be found. Robins will gobble down crab apples, but that’s too big a bite for a bluebird to swallow. They may eat less desirable fruit, like sumac berries that have little nutrition. They may also visit feeders and eat sunflower hearts, suet or peanut butter. A male robin took over the sunflower heart feeder at my folks’ place in Story City for a couple of winters and wouldn’t let other birds feed while he was there. Some folks put out little trays of meal worms to help wintering bluebirds, but other birds find them just as tasty. Chopped-up cooked eggs have been used, too. I put a special suet feeder out by the bluebird box that will be easier for them to land on and feed if they visit again. It’s stocked with two kinds of suet cake. I sure hope it helps them survive the hunger moon to spend another summer bringing joy to our yard.
Steve Lekwa is a former director of Story County Conservation.