“Jay, jay, jay!” Every morning last winter I awoke to the loud cries of a flock of 17 blue jays dancing around my feeder. They gorged on sunflower seeds and suet, scaring away smaller birds, then left, only to return in the afternoon. I ended up buying a second feeder for the smaller birds, which was more difficult (though not impossible) for the jays to feed from.
This boisterous group was a foraging flock. Like many species of birds, blue jays change their behavior from summer, when breeding birds live in pairs, to winter, when they often gather in groups. In summer, blue jays feed and raise their young mostly on insects, while in winter, they shift to fruits, nuts, and seeds. As biologist Bernd Heinrich explained in his book Winter World, these food sources are widely dispersed, but occur in large clumps that groups of birds can detect more easily by combining their scouting efforts. Another advantage of winter flocks is that many eyes are better for detecting predators. » Continue Reading.