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Birds occupy many levels of trophic webs, from mid-level consumers to top predators. As with other native organisms, birds help maintain sustainable population levels of their prey and predator species and, after death, provide food for scavengers and decomposers.
Many birds are important in plant reproduction through their services as pollinators or seed dispersers. Birds also provide critical resources for their many host-specific parasites, including lice that eat only feathers, flies adapted for living on birds, and mites that hitchhike on birds from plant to plant and even between countries.
Some birds are considered keystone species as their presence in (or disappearance from) an ecosystem affects other species indirectly. For example, woodpeckers create cavities that are then used by many other species. After the extinction of the dodo, it was discovered that a tree whose fruits had been a primary food item of the dodo was unable to reproduce without its seeds passing through the dodos’ digestive tracts, which process scarified the seed coat and enabled germination.
Birds and humans
Birds have been integral to humans since prehistory. To birds’ detriment, they and their eggs have been an important human food source since humans evolved, and we have hunted many species to extinction. Feathers, usually obtained by killing their original owners, have been used as adornment in hats, headdresses, and capes. Birds are popular as “pets” throughout the world, and the pet trade has driven many species to the edge of extinction.
More benignly, birds appear in ancient art and mythology worldwide. Birdsong enriches the outdoors for many people, and birdwatching is one of the fastest-growing recreational activities. Birds also were the primary inspiration for human flight.
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Common crowned pigeon (Goura cristata). © Paddy Ryan
Flamingos feed on brine shrimp. © Pierre Fidenci
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