Barn swallows eat an enormous amount of insects and are very important in the control of their populations. Barn swallows are also a useful food source for many predators.

Molothrus occasionally lay their eggs in barn swallow nests. If the barn swallows incubate the eggs and raise the cowbird chick, they are helping the cowbird population.

Barn swallows sometimes live in a symbiotic relationship with Pandion haliaetus. The barn swallows nest inside or below an osprey nest, which is very big. By nesting near ospreys, the barn swallows are protected from predators, which are driven away by the ospreys. The ospreys benefit because the barn swallows give alarm calls when predators are nearby, alerting the ospreys.

Mutualist Species:

• Pandion haliaetus