Flocks of foraging forest birds are typically a mixture of species. Flocks’ fluid structure illustrate how comity works.
In an Amazon forest canopy, 50 avian species might be seen traveling as a unit. The group is cooperative in keeping an eye out for predators, and not especially competitive. While having similar foraging behaviors, different birds have distinctive styles.
Hunting insects as a group can be a lifesaver. Flock members rely on sentinel species, which also direct the flock’s movements and pace, to sound an alarm if an owl or hawk swoops in. This lets the majority of birds in the flock devote more attention to finding food. Traveling in numbers also lessens a bird’s chance of becoming an unlucky lunch if a predator attacks.
Flocking is a lifestyle. “Birds spend 80-90% of their time in these flocks,” marvels American ornithologist Harrison Jones.
Birds that specialize in less abundant substrates – such as tree trunks, epiphytes, and dead leaves – commonly join flocks for a short time as singletons, for the benefit of greater safety.
Mixed-species flocking only occurs during non-breeding seasons. When the mind turns to mating, birds of a feather flock together.
References:
Harrison H. Jones et al, “Do similar foragers flock together? Nonbreeding foraging behavior and its impact on mixed-species flocking associations in a subtropical region,” Auk (12 February 2020).
Mitchell Walters, “Do foragers of a feather flock together?,” American Ornithological Society (12 February 2020).
“How bird flocks with multiple species behave like K-pop groups,” ScienceDaily (12 March 2020).