Mixed-species foraging flock
Instead of competing with one another for limited resources, some bird species who share the same food source can co-exist in mixed-species flocks.
In fact, the more similar body size, taxonomy, and foraging style two bird species are, the more likely they are to be found cooperating in mixed-species flocks.
Studies have shown that birds in mixed-species flocks are more likely to spot potential food sources,[15] avoid already exploited locations,[16] and drive insects out of hiding.
Studies have shown that some bird species will leave their standard optimal feeding area to travel to a worse foraging location in order to follow the path of a mixed-species flock.
[24] Insectivorous feeding flocks reach their fullest development in tropical forests, where they are a typical feature of bird life.
In the Neotropics the leaders or "core" members may be black-throated shrike-tanagers in southern Mexico, or three-striped warblers elsewhere in Central America.
[28] Core species often have striking plumage and calls that attract other birds; they are often also known to be very active sentinels, providing warning of would-be predators.
Namely, these birds are from families such as the cardinals, Parulidae (New World "warblers"), and in particular Passerellidae (American "sparrows") and Thraupidae (tanagers).
Other members of a Neotropic mixed feeding flock may come from most of the local families of smaller diurnal insectivorous birds, and can also include woodpecker, toucans, and trogons.
[5] Gnateaters are notable for their absence from these flocks,[31] while swifts and swallows rarely join them, but will if there is for example an ant or termite swarm.
[30][32][33][32] Cotingidae (cotingas) are mainly opportunistic associates which rarely join flocks for long if they do so at all; the same holds true for most Muscicapoidea (mockingbirds and relatives), though some thrushes may participate on more often.
Such species include the grey-hooded flycatcher, or the plain antvireo and the red-crowned ant tanager which are often recorded in lowland flocks but rarely join them at least in some more montane regions.
[5] A typical Neotropic mixed feeding flock moves through the forest at about 0.3 kilometers per hour (0.19 mph), with different species foraging in their preferred niches (on the ground, on trunks, in high or low foliage, etc.).
For example, as a flock approaches in the Sinharaja Forest Reserve in Sri Lanka, the typical daytime quiet of the jungle is broken by the noisy calls of the orange-billed babbler and greater racket-tailed drongo, joined by species such as the ashy-headed laughingthrush, Kashmir flycatcher, and velvet-fronted nuthatch.
[35] African rainforests also hold mixed-species flocks, the core species including bulbuls and sunbirds, and attendants being as diverse as the red-billed dwarf hornbill and the tit-hylia, the smallest bird of Africa.
