The Winter: Winter Birds

Every morning right after my first cup of coffee I go out to fill my front yard bird feeders. I cannot leave full feeders out at night because all of the seed would be consumed by my voracious herd of white-tailed deer. Each morning I put a large scoop of black-oil sunflowers seeds into each of the hopper feeders (just enough for the day’s feeding), fill the hanging, wire peanut basket, and throw a couple of handfuls of peanuts and a couple of ears of dried corn on the ground beneath them. I usually have to fill the heated birdbath, too because the deer have started drinking it dry every night! As I walk back to the house I look up in the branches of the tall, black locust tree behind the house and usually see one or two crows watching for their opening to come down and eat the peanuts. The crows know my schedule and anticipate a hearty breakfast!

By the time I get back inside for my second cup of coffee, the crows are hunched over the ground peanuts and the gray squirrels are gnawing on the ears of corn (or running off with any peanuts that the crows haven’t claimed). The ground is cleared very quickly and then the squirrels turn to the hanging peanut basket and the feeder birds begin to arrive.

I want to have the feeders full first thing in the morning because the birds have had a long, cold night of intense metabolic heat generation and are in desperate need of re-fueling. Different species come into the feeders in distinct groups although their timings of arrival vary from day to day. This morning the cardinals were the first to come in for their breakfast followed by the chickadees and titmice. Blue jays pushed their way into the feeder perches whenever they wanted to and noisily dropped down to the ground to take whatever nuts or corn that had been left behind. Juncos, mourning doves and song sparrows pecked around on the ground at the seed spilled from the hanging feeders, and finally the house finches swarmed in and actively fed at the perches. Then there was a pause and the groups cycled back in all over again.

Occasionally, downy woodpeckers and red-bellied woodpeckers come into the feeders (and to the suet cakes if I remember to put them out). Our two Carolina wrens (who amazingly sing all winter!) also come into the feeders in between the larger, single species groups along with the white-breasted and rose-breasted nuthatches. Every once and awhile some different species, often just a single individual, drops in for a snack, sticks around for a day or two, and then disappears from the yard. Last year a wood thrush stayed several weeks (I described him in my blogs as he learned to use his long, insect probing bill to crack open sunflower seeds!). This year a golden-crowned kinglet showed up for Christmas day (he kept to the surrounding arbor vitae bushes gleaning up and down the branches for insect larvae) and just this morning I saw a robin perched up in the backyard locust tree (he looked quite cold and very confused).

One very interesting behavior that can be observed in the many of the winter birds away from the bounty of the yard feeders is the formation of mixed species flocks. The chickadees, titmice and downy woodpeckers in particular join together into large, complex flocks for the winter. At first glance this flocking behavior would seem to be disadvantageous to all of the species and to all of the individuals concerned. Food is in short supply in the winter, so how could the clustering of many individuals that all eat approximately the same prey items (primarily insect larvae) do anything but decrease the survival of respective species? The answer involves the facilitation of food finding and the reduction in the average individual’s energy devoted to searching for food. In the large mixed flock there is a very high probability that some flock member will find a food source (a cache of larvae under some tree bark for example). Exploitation of food sources by the entire flock with the subsequent high probability that another individual will soon find another food cache “smooths out” the boom and bust food cycle of the winter system, and thus increases the survival of a higher percentage of individuals in the mixed flock. Further, from the perspective of the downy woodpecker, flocking with the very alert and excitable chickadees and titmice also increases their awareness of incoming predators and thus adds to their chances of winter survival.

Another interesting natural behavior that was described by Aldo Leopold (author of the “Sand County Almanac”) is the positive response of chickadees to loud, explosive noises (like shotgun blasts or breaking tree limbs). The chickadees swarm toward the sound very energetically (and in a mixed flock carry along the titmice and downy woodpeckers with them). The breaking of a tree limb or the falling of a tree opens up the woody encasement that may be densely inhabited by ants, ant larvae and or other insect larvae. Drawn to the loud noises, these birds can rapidly exploit a suddenly available food source.There is some evidence that chickadees (and, presumably, their fellow flock species) also utilize carrion in the winter. They have also been observed feeding on the gut piles made by deer hunters. Maybe this feeding behavior has also been facilitated by their positive, trophic responses to gun shots and other loud noises.

The main predator that regularly shows up at our yard feeders is the sharp-shinned hawk. The small male and the larger female sharp-shins swoop across our yard at least once a week. Their success rate at securing their prey is not great, but once a month or so I find a pile of plucked feathers (usually from a dove) under one of their perches along the wooded edges of my field. A week or so ago the female sharp-shin started her mating calls (an event that Deborah recorded two years ago). I haven’t seen any immature sharp-shins around the yard or field, though, so it seems that their winter, mating “dances” have not been productive.

Bird songs are a very beautiful aspect of nature. Theories have been proposed that the first music made by humans was an attempt to recreate and control the haunting beauty of these natural songs. The fields and woods do seem empty in the winter without the whistles and melodies of our songbirds. We do hear the buzzing of the chickadees, and the rapping of the woodpeckers, and the occasional singing of the male Carolina wrens, but the lack of full chorus singing makes the fields and the woodlots around us seem empty and barren.

Why don’t most of the birds sing in the winter? The answer lies in the reason for bird songs in the first place. Although many birds do use song as a mechanism of individual recognition and contact, the primary reason for song is advertisement of themselves! The male bird sings to declare his vigor, his individual territory, and to attract a mate (or as many mates as possible depending on the species!). Mating is not one of the biological functions of the winter season, so most songs are left unsung until spring.