Primal urges drive bird behavior

By Bob Duchesne, Special to the BDN
Posted March 09, 2012, at 2:23 p.m.

Sex and food. There. Now you know everything a bird thinks.

The first is easy enough to understand, but the latter is more complicated. At the same time a bird is trying to eat, it is trying to not be eaten. That explains much of the behavior you see at your bird feeder. Just for fun, take note of how birds act at the feeder. Each species has its own survival strategy.

You’ve noticed that chickadees come to the feeder, take a seed and fly off. So do nuthatches. This winter, I’ve had a tufted titmouse coming to my feeder for the first time. I’ve been trying to get a photo to accompany this column, but the little twerp won’t hold still. He’s there for a moment and then, poof, gone. These birds feel uncomfortable out in the open, where they are easy pickings for a marauding hawk. Their strategy is to snatch food and fly to safety. That’s why it is important to hang feeders where there is a little bit of nearby cover. These grab-’n’-go birds also need a close tree branch where they can scan for predators.

Hawks in the Accipiter family (familiarly known as woodland hawks) are opportunistic around a feeder. This group includes sharp-shinned and Cooper’s hawks and northern goshawks. All will stake out a bird feeder and return periodically. Though most head south for the winter, a few sharp-shinned hawks linger here, and Cooper’s hawks are even more likely to hang around in a mild season. Goshawks expand their range southward in winter, but they are generally nonmigrants. Even if these hawks are not consciously haunting a feeder, the activity of multiple birds will attract their attention. The small birds know this, hence their strategy of darting to the feeder from cover.

On the other hand, finches sit on the feeder and gobble down one sunflower seed after another. Goldfinches even call attention to themselves, noisily mobbing a thistle feeder, perching on it for several minutes, seemingly oblivious to the danger. That’s because their strategy is different. For them, there is safety in numbers. With so many eyes in the flock watching out for menace, it’s hard for a hawk to sneak up on lunch. If one bird spots danger, the congregation can scatter in the blink of an eye.

Size matters. Blue jays, northern cardinals and evening grosbeaks are large enough to be a struggle for a sharp-shinned hawk. These birds feel more comfortable taking a sit-down meal. Hairy and downy woodpeckers are both forced to perch on a suet feeder for a few moments while pecking away at lunch, but the smaller downy woodpecker spends more time gazing around and less time stationary.

Birds that rummage on the ground under the feeder have a different challenge. Besides hawks, they are more vulnerable to terrestrial predators like cats. Notice how nervously they forage, looking up and peering around with every step. For them, too, there is safety in numbers. It is commonplace to see small flocks of dark-eyed juncos coming in together. Sparrows often join them. Even the slightest unexpected motion sends them all flying, only to return moments later when the threat is unrealized. They flee first, ask questions later.

Speaking of sparrows, raise your hand if you have American tree sparrows foraging under your feeder. Not sure? This little tyke can be confusing. It breeds widely across the Canadian subarctic, and many filter into Maine in winter. It resembles a chipping sparrow. Both species have a line through the eye, though the line is black on a chipping sparrow and rufous on the tree sparrow — the same color as the cap. The tree sparrow has a plain breast adorned with a dark smudge of a spot in the middle. In this part of the country, it is unlikely a chipping sparrow and a tree sparrow will be present at the same time. Their seasons underneath your feeder seldom overlap. Both will feed on the ground under the feeder like the juncos, and both will pop up onto a platform feeder, but not a perch feeder. They appreciate the cover of nearby bushes, which increases the chances of them appearing under your feeder. But what I like most about tree sparrows is this: they have the sweetest little call note of all the birds I know. Short, delicate and bell-like, it makes me smile every time.

Bob Duchesne serves in the Maine Legislature, is president of the Penobscot Valley Chapter of Maine Audubon, created the Maine Birding Trail and is the author of the trail guidebook of the same name. He can be reached at duchesne@midmaine.com.

http://bangordailynews.com/2012/03/09/outdoors/primal-urges-drive-bird-behavior/ printed on October 23, 2014