摘要：
Interspecific segregation of foraging activities of nuthatches and woodpeckers was investigated from June 1964 to June 1966 in a stand of ponderosa pine. The composition and density of populations were assessed throughout the year. Location of foraging activities was quantified by measuring the length of time each species occurred in specified zones of the environment. Interspecific differences of zonation were statistically analyzed for the reproductive and non-reproductive seasons separately. White-breasted and Pigmy Nuthatches and Hairy Woodpeckers nested in the area and were sympatric throughout the year. Red-shafted Flickers and Williamson's Sapsuckers nested in the area but were sympatric with the 2 nuthatches and Hairy Woodpecker only during the reproductive season. Red-breasted Nuthatches nested at higher elevations and were sympatric with the Hairy Woodpecker and other nuthatches only during the non-reproductive season. Pigmy Nuthatches foraged most extensively in the foilage of live pine in both seasons. White-breasted Nuthatches concentrated their foraging activities on the trunks and large branches of pine. Zones used most extensively by all nuthatches were mutually exclusive in both seasons. Zones of Hairy Woodpeckers and Williamson's Sapsuckers overlapped considerably in the reproductive season. Hairy Woodpeckers foraged for arthropods on the surface of trunks and branches of living trees but more extensively for subcortical arthropods of dead trees, stumps and logs. Williamson's Sapsuckers foraged almost exclusively for ants on trunks of living pines. In the non-reproductive season, Hairy Woodpeckers foraged most extensively for seeds of pine cones. Williamson's Sapsuckers foraged almost exclusively on phloem of trunks of living pines. Foraging activities of Red-shafted Flickers were confined to the ground and thus segregated from the major foraging zones of all other birds. Nuthatches and woodpeckers were shown to be segregated by spatial and behavioral differences of foraging activities and by temporal differences of their residential status. It is concluded that climate, available space and competition for food were important in the evolutionary development of these interspecific differences.
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文章 : 英语