It’s not uncommon for still, silent winter landscapes to be suddenly disrupted by distant birdcalls. Within moments, half a dozen kinds of birds appear, flitting among tree branches, climbing up trunks, hanging upside down from twigs. For just a few minutes, the birds bring life to the area with colors, sounds and movement. Then they all fly away together. These mixed flocks of birds are one of winter’s special features. If you’re aware of the activity, you may be able to observe them practically anywhere in North America, and possibly in your own backyard.
Safety in Numbers
So why do we see these mixed flocks? It’s probably not just because birds enjoy one another’s company. For many, there’s a good reason for flocking: It’s safer than traveling alone. Searching for food out in the wild takes lots of concentration, and it’s hard to look for seeds or berries and watch for danger at the same time. With more birds in the flock, there’s a better chance that a swooping hawk or prowling cat will be spotted while there’s still time to sound the alarm and make a getaway.
Leaders of the Pack
When you see a mixed flock moving through the trees, it may seem as if they’re all acting independently. But there are definite leaders and followers.
In treetop flocks, the leaders are usually chickadees. These busy, acrobatic little birds live in pairs or family groups during the summer, but in winter they gather in groups of a dozen or more. These flocks stick together throughout the cold months. As they make a regular circuit through the woods, other small birds fall in with them, following the lead of the chickadees—nuthatches, brown creepers, titmice, kinglets, downy woodpeckers and yellow-rumped warblers among them. These birds are clued in to the voices of their chickadee leaders, and when they hear an alarm note, they immediately look around for danger.
North America has several species of chickadees in different regions—including black-capped chickadees across the Northern states and Canada, Carolina chickadees in the Southeast, mountain chickadees in the Rockies and chestnut-backed chickadees in the Pacific Northwest—but they all serve as flock leaders in their own areas.
Click link to read more! http://www.birdsandblooms.com/birding/birding-basics/mixed-winter-flocks/