Golden-crowned Kinglet – photo by Jeff Larsen
Winter birding can be slow at times. Then all at once, a cloud of different bird species appears. Noisy social and alarm calls signal their arrival, at times punctuated by the beat of a woodpecker. If you hold still and be quiet, the flock will move right by you. You will become immersed in a mixed flock!
In western Washington, you might first notice the Kinglets. Golden-crowned Kinglets come down to eye-level, so you can see them much more easily and with far less neck strain than when they are high in the canopy of conifer trees. Ruby-crowned Kinglets are the boldest. They perch within a few feet of you, and sometimes raise their ruby crown while chattering away in Morse code phrases. Accompanying the Kinglets are often Black-capped and Chestnut-backed Chickadees, Dark-eyed Juncos, Bushtits, Spotted Towhees, Steller’s Jays, Red-breasted Nuthatches, Yellow-rumped Warblers, the occasional Anna’s Hummingbird, Bewick’s Wren, Brown Creeper and/or Downy Woodpecker. Other species might join in too. It’s an impressive assembly, all in constant motion.
What makes birds known for their territoriality hang out together in mixed flocks? Two main factors seem to be at play. First, mixed flocking behavior occurs primarily in the non-breeding season when they are far less territorial. Second, it occurs when food is scarce (winter). By being in a mixed flock, birds benefit from group feeding opportunities and the built-in alarm system that the other birds provide. Birds in mixed flocks can spend more time feeding and less time watching their back sides. By joining a mixed flock, they will also find more food by noticing where and how other birds forage. As David Sibley said in The Sibley Guide to Bird Life and Behavior: “Flocking is also partially a response to the problem of searching for food, as many eyes can search a large region more effectively than a single pair of eyes.” Finally, mixed flocks may confuse predators when members of the flock disperse in multiple directions.
Be patient and observant in your next walk in a winter woodland or park. Eventually, you will encounter a mixed flock of birds. When you do, it’s quite a spectacle.
Sources: Mixed-Species Flocking article by Paul Ehrlich, David Dobkin and Darryl Wheye, Stanford University; Ornithology by Frank Gill; The Sibley Guide to Bird Life and Behavior by David Sibley; Washington Post: Birds of Different Feathers Flock Together by Patterson Clark – Urban Jungle Feature, Feb. 1, 2011.
