(some of this information was first published in a January 15, 2014 blog)
Every morning right after taking Izzy for her walk and well before 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 sunflower seeds into each of the hopper feeders (usually just enough for a day’s feeding) and throw a couple of handfuls of peanuts and a scoop of shelled corn on the ground beneath them. I usually have to fill the heated birdbath, too (the deer have also taken to drinking out of it at night!). As I walk back into the house I look up in the branches of the tall, black locust tree behind my house and usually see one or two crows watching for their opening to come down and eat the peanuts. They start cawing and bobbing their heads when we make eye contact, and often by the time I get back inside to get the coffee started they are in the front yard, hunched over the peanuts. Soon the gray squirrels arrive to scoop up the corn and do their early morning acrobatics in sunflower seed feeders. Some mornings they even get a few peanuts that the crows have overlooked. The ground is cleared very quickly and then 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. Often the cardinals are the first to come in for their breakfast followed by the chickadees and titmice. Blue jays then push their way into the feeder perches and noisily drop down to the ground to take any nuts or corn that have been left behind. Juncos, mourning doves, white- throated, white capped and song sparrows peck around on the ground at the seed spilled from the hanging feeders, and finally the house finches swarm in and feed. Then there is usually a pause and the groups cycle back in all over again.
Occasionally, downy woodpeckers, red-bellied woodpeckers and northern flickers 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 the 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. A few winters ago a wood thrush stayed around for several weeks. He used his long, insect grabbing bill to crack open sunflower seeds! Last year a golden-crowned kinglet showed up for Christmas (he kept to the surrounding arbor vitae bushes gleaning up and down the branches for insect larvae), and every once and a while a stray robin stops by (usually looking quite cold and 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 shot gun blasts or tree limb breaks). 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 full of ants, ant larvae or other insect larvae. Drawn to the loud noises, these birds can rapidly exploit a suddenly available food source.
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 or a cardinal) under one of their perches along the wooded edges of my field. Soon the female sharp-shin will start her mating calls (an event that Deborah videoed two years ago). I haven’t seen any immature sharp-shins around the yard or field, though, so it seems that their winter, mating “dance” has not been productive.
Bird songs are one of the most beautiful aspects 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, the raspy whistles of the white-throated sparrows, and the occasional, rolling trills of the Carolina wrens, but the lack of full chorus singing makes the yards and the woodlots 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.
I guess that a better question might be, why do some birds sing in the winter anyway? I am going to ponder that one for a while.