This method of control is principally limited to geographical or ecological islands and perennial crops.

In some parts of the mainland, mammals are being completely eliminated inside fenced areas to create "ecological islands".

Critics respond that the park will still suffer the effects of being isolated from surrounding areas, becoming in effect an ecological island.

And island populations - including those trapped within ecological islands, such as a park surrounded by development - tend to be small.

The Yellowstone bison herd lives on an ecological island with no predators.

It serves as an ecological island giving large animals like white-tailed deer a home base.

Only on small, isolated habitats known as ecological islands can the phenomenon be observed.

Grizzlies from elsewhere do not immigrate to this ecological island.

For half a century the city of West Berlin was something of an ecological island.

The plateau of the tepuis is completely isolated from the ground forest, making them ecological islands.