Be suspicious of flocking birds this winter

Birds of a feather flock together. Except that most don’t. From now until next spring, if you see a flock of birds, get suspicious. Few species flock, and you can often identify the flockers before seeing any field mark.

The top reason birds flock together is safety. It’s easier for predators to sneak up on one bird than to sneak up on a hundred. There are too many eyes looking for trouble. If a raptor does attack, the odds of survival are high, since the risk is spread out among them. Figure 99 out of 100 birds survive a successful hawk attack.

However, to pull off this flocking strategy, there must be enough food to feed the entire group. Insect-eating birds rarely find a feast big enough to sustain a flock. Hence, warblers, flycatchers, thrushes and woodpeckers rarely travel in large groups.

Swallows do, but only because they are nimble enough to snatch a meal out of the air. They rely on marshes teeming with insects as migration stopover points. Swallows leave early in autumn, before colder weather shrinks the aerial food supply.

Shorebirds in migration form big flocks. Sandpipers and plovers are particularly vulnerable to falcons, and they’ve perfected the flocking defense. When chased, they pack close together in the air, cartwheeling elusively, making it harder for the falcon to cull out a single victim. Most small shorebirds have white stripes in the wings and tail, which flash in mesmerizing fashion, further confusing the pursuer.

Birds that eat seeds are more likely to flock. Sparrows stay near the ground, foraging among grasses and weeds. Expect to see roadside flocks in mid-autumn, as they head south for the winter. Flocks will often contain multiple sparrow species, including dark-eyed juncos.

Finches stay in the treetops, feasting on small cones and catkins. Since their food supply is available all winter, they aren’t compelled to go south. More often, finch flocks simply wander around, looking for the best crops.

Three small finches will gather in flocks over the next several months. American goldfinches are familiar feeder birds. They are bunching up right now.

Pine siskins nest across the northern forest. In fall, they begin to flock up in big numbers. They may head south or west for the winter, or they may stick around here, depending on where the food is best. Either way, bunches of them will start moving around soon.

Common redpolls nest farther north and visit Maine only in winter. They, too, form impressive flocks, roaming nomadically. If the food supply is good in Canada, they may not even make it this far. When they do, 50 or more birds are likely to be in a single flock.

Crossbills are slightly larger than the three small finches. They also roam in flocks, searching for the best cone crops. Both red and white-winged crossbills can dine on the same cones. But in Maine, the red crossbills tend to relish the heavier cones. They dined on pine cones in southern Maine all last winter. Meanwhile, the white-winged crossbills stuck to the northern forest, primarily hitting spruce cones.

The two largest finches likely to flock around your neighborhood are pine and evening grosbeaks. Both dine on seeds and fruit. Pine grosbeaks are fond of crabapples and ornamental berries. Evening grosbeaks show a preference for sumac. Regardless, their ability to eat both seeds and fruit gives them the facility to go just about anywhere they please and find enough food.

Cedar waxwings rely on fruit in winter, chowing down on the same berries sought by the pine grosbeaks. It’s sometimes a race to see who gets there first. So far, the waxwings are winning.

Cedar waxwings, and their Bohemian waxwing cousins, are really in a class by themselves. They’ll get their own dedicated column soon. Stay tuned.

I saw a flock of cedar waxwings alight in a tree near the Bangor Mall last week. I was still some distance away, but I was pretty sure of the identification. I had to be cautious, since European starlings flock around the mall year-round, particularly as the days get shorter. Starlings form big flocks, but they don’t tend to travel far.

Finally, if chickadees and blue jays sense a winter food shortage coming, you may see them flocking south.

To sum up, give flocking birds your attention over the next two months. Sparrows work the roadsides. Finches work the treetops. Waxwings work anytime, anywhere. Some worried birds gather just to flee the Maine winter. Misery loves company.