In an analysis of nearly 100 North Florida flocks, Florida Museum of Natural History researchers found similar bird species were significantly more likely to flock together than hunt alone, working as a group to stay safe from predators while cruising the canopy in search of insects. Species kept competition within the flock low, however, by differentiating their foraging technique, their choice of hunting spot or the general distance they kept from a tree trunk.
In other words, think of flock dynamics like a K-pop band, said study lead author Harrison Jones.
"You have to be similar enough to the other members to get along as a group but specialized in some way: There's the leader, the one who raps, the one who plays guitar," said Jones, a doctoral student in the University of Florida's department of biology. "It's the same with birds. They hang out together because they share things in common, but they can't share too much. If you're so similar that you're eating each other's lunch, then you have a serious problem."
North Florida's winter flocking community is "probably the most complex in North America," Jones said, featuring dozens of migratory species and a bevy of foraging opportunities. Still, the researchers were surprised to see how specialized the birds' foraging habits were—a feature more reminiscent of the Amazon than North America.
[...]Species that pick insects off live leaves and nab them in the air—the most common foraging techniques—were relatively abundant in mixed flocks. These included ruby-crowned kinglets, blue-gray gnatcatchers and pine warblers. But birds that hunt exclusively in harder-to-find material tended to be represented by a single member per flock. These specialists called repeatedly, as though to warn others of their kind "Hands off! This is my flock," Jones said.
[...]Mixed-species flocks only occur during winter, birds' non-breeding season. Finding enough food in colder months is vital for birds, which must strike the right balance between putting on sufficient body fat to survive the night while staying lean enough to make a quick escape from a predator, Jones said.
Hunting insects as a group can be a life-saver. Flock members rely on sentinel species, which also direct the flock's movements and pace, to sound the alarm if an owl or hawk swoops in. This allows the majority of birds in the flock to devote more attention to finding food. Traveling in numbers also lessens a bird's chance of being the unlucky victim if a predator attacks.
Some research really is going to the birds.