Late Summer Flocking

As the days continue to shorten and summer begins to lose its intensity, attentive birders notice flocking behavior in many species.  For most birds (goldfinches are an exception), their breeding season has ended and their territorial instincts have faded; migrants gather in flocks to prepare for their southward journey while many permanent residents form flocks to evade predators and to improve the efficiency of their foraging.

Last evening, I encountered a flock of 30+ barn swallows, strafing a nearby lake to fuel up for their journey to South America; then, this morning, I watched as a flock of 18 snowy egrets moved southward above the South Platte Valley.  Among other late summer migrants that travel in sizable flocks are blue-winged teal,  Swainson's and broad-winged hawks, shorebirds, common nighthawks, American white pelicans and Franklin's gulls.  Non-migrant flocks of cedar waxwings, doves, robins, starlings and various blackbirds are also increasingly common as summer winds down.

While the influx of winter songbirds will not begin until mid October, these late summer flocks offer some excitement as birders try to recover from the mid summer doldrums.  Better yet, they are a preview of autumn migration spectacles and hint at the cool, crisp days that lie ahead.