Shore Birds

views updated

Shore Birds

Shore birds, sometimes called waders, include representatives from a number of families in the order Charadriiformes, including plovers (Charadriidae), oystercatchers (Haematopodidae), avocets and stilts (Recurvirostridae), jacanas (Jacanidae), and sandpipers, snipe, phalaropes, and their close relatives (Scolopacidae).

Despite their classification in the same order, shore birds are not closely related to each other. Their affinity is ecological, and involves a tendency to live near water. Collectively, species in the families listed above comprise a highly varied and widespread group of birds that utilize a great range of habitats, even deserts. However, most of these shore birds are commonly found in and around the shores, beaches, and mudflats of marine and fresh waters.

Many species of shore birds are hunted as game birds. In North America, hunted species of shore birds include relatively inland species such as snipes (Capella gallinago ) and woodcocks (Philohela minor ), and species more typical of marine habitats such as black-bellied plovers (Squatarola squatarola ), whimbrels (Numenius americanus ), and willets (Catoptrophorus semipalmatus ). In recent decades, hunting of these species has been relatively limited. However, during the nineteenth century and first decade or so of the twentieth century shore birds (and most other hunted species of wildlife) were relentlessly hunted during their migrations and on their wintering grounds. As a direct result of this overhunting, and to some degree because of losses of natural habitat, the populations of most species of shore birds declined drastically in North America and elsewhere. One initially uncommon species, the Coopers sandpiper (Pisobia cooperi ), became extinct by 1833 because of excessive hunting. A larger species, the eskimo curlew (Numenius borealis ), was reduced to extremely small numbers, and, as the population has not recovered, this shore bird remains on the list of endangered species. Another example is the marbled murrelet (Brachuramphus marmoratus ), a small seabird that lives along the Pacific Northwest from the Bering Sea to central California is also listed as a threatened species under the Endangered Species Act. Potential causes of its decline in population are the loss of suitable nesting habitat, accidental death in gill-nets, oil pollution, increases in predator populations, and declines in food supplies.

Many species of shore birds predictably congregate in large numbers at particular times of year, generally during the spring or autumn migrations, or during winter. For some smaller species, those massed populations can be extraordinarily large. For example, during the fall migration more than one million semipalmated sandpipers (Calidris pusilla ) congregate to feed on invertebrate-rich mudflats in the Bay of Fundy of eastern Canada, appearing in flocks that can exceed hundreds of thousands of individuals. Clearly, these mudflats represent habitat that is critical to the survival of semipalmated sandpipers.

See also Stilts and avocets.