Are Keystone species always predators?

Keystone species questions (general and simple)?

• in preserving ecosystems top level predators are often targeted as keystone species. Why would this be sound from an ecological perspective? what effects does the loss of these trying ...show more

• Answer:

  Unless you live in the Southeast, you might not think of the American alligator as a keystone species. They maintain pools during the dry season to allow the fish and amphibians to survive (and eat their fair share of them). They protect the birds that nest in trees that grow out if those home pools. If some unfledged heron falls out of the nest, the alligator may as well eat it, rather than letting it be attacked by fire ants or some such. Alligators are also about the only predator that can eat gars, helping to keep their numbers in check. Restrictions on alligator hunting were quite effective in restoring the population.