Biological instinct is driven by three things, to stay alive, to find food, and to breed, passing on a genetic legacy. But competition for mating rights can be fierce. Animals grow display structures and weapons to help them impress the opposite sex.
All animals, no matter how big or small, face a daily struggle to find food. During harsh winters and devastating droughts, those pressures escalate, and when resources run low, sometimes the only option is to fight.
All animals fit into a food chain, feeding on those below, but there is nearly always another link in the chain, something that wants to eat them. A look at survival in different food chains.
Sometimes just staying alive is a fight, especially in the bleakest polar regions, the driest deserts, the highest mountains, and the sharpest season changes. Animals battle the environment and each other to stay alive.