Marine life same environmental problems and feeding niches have resulted in similar adaptations. Examples include albatross, penguins, gannets, and auks. In general, marine birds live longer, breed later and have fewer young than terrestrial birds do, but they invest a great deal of time in their young. Most species nest in colonies, which can vary in size from a few dozen birds to millions. Many species are famous for undertaking long annual migrations, crossing the equator or circumnavigating the Earth in some cases. They feed both at the ocean's surface and below it, and even feed on each other. Marine birds can
Birds of New Zealand hedgehogs, and Australian possums also put pressure upon native bird species. The flightless birds were especially sensitive. Consequently, many bird species became extinct, and others remain critically endangered. Several species are now confined only to offshore islands, or to fenced "ecological islands" from which predators have been eliminated. New Zealand is today a world leader in the techniques required to bring severely endangered species back from the brink of extinction. Many bird species were introduced during the early years of European settlement to control insects as New Zealand birds species generally preferred a native bush habitat rather than the open