Animals compete with each other on two levels.

When someone guts a freshly catched fish on the seashore, the person quickly attracts an entourage of seagulls. Each seagull tries to eat as much of the fish remains as possible. When immersed in this activity, the seagulls will from time to time make noises and aggressive movements at each other. The seagulls are competing for food. As all the birds belong to the same species, the scene is an example of intraspecific competition. Larger individuals usually succeed in getting more food than smaller individuals.

Common gulls competing for fish remains.

The noise made by common gulls attracts other birds. After a while, they are paid a visit by a larger European herring gull (pictured below). Herring gulls are stronger than common gulls, and they will quickly drive the other birds away to eat up most of the remaining food.


An European herring gull (center) driving common gulls away from the fish.

Why don't the herring gulls arrive at the scene straight away to eat the fish? Larger species usually dominate smaller species in nature. However, herring gulls are considerably more shy than common gulls. They will stay away for as long as they see a human near the fish remains. However, immediately after the human leaves the scene, the herring gulls race to drive away the common gulls from the food. This situation is an example of interspecific competitions.