Food overlap among coexisting sandpipers on northern Alaskan tundra

摘要: Most closely related sympatric bird species differ in their food-gathering structures, foraging techniques, and/or food preferences, with the result that they take different kinds of foods (Lack, 1954; Newton, 1967). Specialization diet presumably evolves as a consequence competition for limited resources and is considered essential continued coexistence Mayr, 1963). This type specialization also reflects importance an evolutionary factor natural populations. We have found, however, diets birds breeding on Arctic tundra overlap to strikingly high degree. The circumstances behind this are straightforward: taxonomic diversity sources relatively simple community structure. Neither these appears provide, space or time, range opportunities permitting variety observed at temperate latitudes farther south. questions then arise, how can arctic such near Point Barrow, Alaska, support abundance occurring there, do birds' interact regard supply? These large continuing foci research northern Alaska. Results examination feeding ecology should provide insight into two other problems which concern ecologists; namely, more be allow them live sympatrically, conversely, what consequences, ecologically behaviorally, when similar exploit common source? paper focuses foodexploitation patterns four widely sandpipers genus Calidris breed regularly abundantly red-backed (C. alpina), pectoral melanotos), Baird's bairdii) semipalmated pusillus) sandpipers. In addition, five congeners present occasionally Barrow area there: one almost every year, usually sparsely, but occasional years commonly fuscicollis); only sporadic infrequent breeders, small numbers (canutus, alba, mauri ferruginea). A sixth (ruficollis) occurs sporadically may yet found breed. largest group avian its members not insectivores present. Other shorebirds, ducks, gulls, few passerines there same general Thus, sympatry use source extend beyond here. But comprise substantial part insectivore fauna area. Given variations basic theme structure, physiology behavior (the Calidris) grass-sedge we seek clues from differences between factors coexistence. Our immediate objective describe examine degree overlap.