Endangered Birds

With colonial expansion and the technological advances of the 18th and 19th centuries, humans hunted birds on an unprecedented scale. This time period witnessed the extinction of the great auk, a large flightless seabird of the North Atlantic Ocean that was easily killed by sailors for food and oil. The Carolina parakeet also became extinct in this time period, although the last one of these birds survived in the Cincinnati Zoo until 1918.

In the 20th century, a time of explosive growth in human populations, the major threats to birds have been the destruction and modification of their habitats. The relentless clearing of hardwood forests outweighed even relentless hunting as the cause of the extinction of the famous passenger pigeon, whose eastern North American populations may have once numbered in the billions. The fragmentation of habitats into small parcels is also harmful to birds, because it increases their vulnerability to predators and parasites.

Habitat fragmentation and reduction particularly affects songbirds that breed in North America in the summer and migrate to Mexico, the Caribbean, Central America, and Colombia for the winter. In North America, these birds suffer from forest fragmentation caused by the construction of roads, housing developments, and shopping malls. In the southern part of their range, songbirds are losing traditional nesting sites as tropical forests are destroyed and shade trees are removed from coffee plantations.

Pesticides, pollution, and other poisons also threaten today's birds. These substances may kill birds outright, limit their ability to reproduce, or diminish their food supplies. Oil spills have killed thoUKnds of aquatic birds, because birds with oil-drenched feathers cannot fly, float, or stay warm. Acid rain, caused by chemical reactions between airborne pollutants and water and oxygen present in the atmosphere, has decreased the food supply of many birds that feed on fish or other aquatic life in polluted lakes. Many birds are thought to be harmed by selenium, mercury, and other toxic elements present in agricultural runoff and in drainage from mines and power plants. For example, loons in the state of Maine may be in danger due to mercury that drifts into the state from unregulated coal-fired power plants in the Midwest and other sources. Global warming, an increase in the earth's temperature due to a buildup of greenhouse gases, is another potential threat to birds.

Many laws have been enacted to protect birds. More than 120 countries signed the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), which went into effect in 1975. This treaty regulates or restricts the trade of endangered birds, including many parrots. Treaties between the United States, Canada, and Mexico protect all migratory birds native to North America. In the United States, the Endangered Species Act promotes species and habitat protection.

Other means of protecting birds include the creation of sanctuaries and captive breeding programs. Sanctuaries for birds exist all over the world-two examples are the Bharatpur Bird Sanctuary in India's Keoladeo National Park, which protects painted storks, gray herons, and many other bird species; and the National Wildlife Refuge system of the United States. In North America, some endangered birds are bred in settings such as zoos and specialized animal clinics and later released into the wild. Such breeding programs have added significantly to the numbers of whooping cranes, peregrine falcons, and California condors. Many countries, including Costa Rica, are finding they can reap economic benefits, including the promotion of tourism, by protecting the habitats of birds and other wildlife.
The protection of the earth's birds will require more than a single strategy. Many endangered birds need a combination of legal protections, habitat management, and control of predators and competitors. Ultimately, humans must decide that the bird's world is worth preserving along with our own.