Eat or Be Eaten

The fox in a forest ecosystem is a predator. A predator is an animal that eats other living animals. The rabbit is the fox's prey. Prey are the animals. the energy flow through the forest ecosystem doesn't stop with the fox.
The fox isn't the top predator in the forest. It, too, is prey at ceratin times. Large predators such as wolves will hunt and eat foxes.
Another important role in an ecosystem is that of a scavenger.
A scavenger is an animal that eats other animals that have died.
Crows are scavengers within a forest ecosystem.