The rainforest offers a rich variety of living things. Part of that richness can be seen in the flocks of birds that cooperate in the canopy, even though the flocks are made up of several species.
The rainforest is actually two forests in one. The canopy that's formed by the tree tops supports an entirely different type of life than the part of the forest growing beneath the canopy. This lower forest is called the "understory." Flocks made up of various species of birds search for food, usually insects, in their respective territories – either in the canopy or in the understory. Each flock has its own sentinel who watches for predators and warns the rest when danger is near.
This arrangement leaves the sentinel with little time to search out its meals. So it resorts to a little trickery to feed itself. It watches the other birds forage, in addition to watching the sky. When it sees the others turn up some good insects, it shrieks the predator alarm. Then, while the other birds are distracted, it chases down the insects before the others can get to them. It appears that the other birds can tell when they are being fooled. When they hear the alarm, they immediately look at the sentinel. If the sentinel is diving for cover, they know the alarm is real. If the sentinel is diving for their meal, it's too late to do anything about it.
In effect, the other birds are trading some of their hunting skills in return for the alarm services of the sentinel. It's the Creator's wise arrangement where everyone uses his gifts for the good of all.