Flock (birds)

A flock is a gathering of individual birds to forage or travel together. Birds often form flocks, especially when they are migrating to new places. Flocking helps birds find food and stay safe from predators, although it can sometimes have downsides for individual birds.

Flocks are usually made up of birds of the same kind. However, it is also common to see mixed flocks, where two or more bird species travel and feed together. Birds that form mixed flocks are often similar in their family tree and share traits like size and shape. This mixing helps protect birds from predators, especially in places like forests, where warning calls are important for spotting danger early. This leads to the creation of many mixed-species feeding flocks.

Mixed flocks

Mixed flocks happen when birds of different species fly together. In these groups, there are two types of behavior: sallies and gleaners. Sallies fly through the air catching insects, while gleaners look for food in trees and bushes. When there is more food in the air, like during a forest fire when insects fly out, there are more sallies in the flock.

Birds that are less common often join these mixed flocks. Even though they might seem less important, they get more food and are safer from predators because it is harder for predators to catch just one bird in a large group.

Safety from predation

Birds in flocks work together to stay safe from predators. When one bird spots danger, it can warn others by making a special sound. This helps the whole group react quickly. Even though calling out might alert the predator to their location, it still helps because the birds can all act together to defend themselves.

Young birds learn from older ones how to stay safe. For example, thick-knees in Chile stay in groups with both adults and juveniles. Being in a flock means birds spend less time looking for danger and more time doing other things. However, as flocks grow larger, birds might also compete more with each other for space and resources. Overall, flocking helps birds face predators more effectively than if they were alone.

Foraging in flocks

Birds that stay together in flocks can find food better than birds that search alone. When one bird spots food, it can alert the others, so the whole group benefits. However, this can also lead to problems, like stronger birds taking food from weaker ones.

Some birds, like the Harris's hawk, hunt together in special ways. A small group of hawks will work as a team to catch larger animals, such as a rabbit. By working together, they can catch bigger prey and use less energy.

Black sun

Main article: Sort sol

In Denmark, a special event happens twice a year called sort sol ("black sun"). During this time, huge groups of European starlings gather and make beautiful patterns in the sky. These birds are getting ready to travel and find food. Staying together helps keep them safe from hawks.