Bird use of arctic tundra habitats at Canning River Delta, Alaska

Abstract

Seasonal patterns of abundance of shorebirds and Lapland Longspur were studied at the Canning River delta. Study plots with differing habitat characteristics were examined: upland, mesic, and lowland tundra, and coastal saline flats. Nesting density was greatest in the mesic plot, but the lowland received intense use by late summer transients; use of the saline habitat was consistently high. Cold weather in July, 1980 probably reduced prey availability. Aquatic habitats, especially polygon troughs, produced a high proportion of the adult insect biomass. Comparison of energetic requirements of birds with the energetic value of their prey supply suggests that food could have limited reproductive success. Availability of both aquatic and terrestrial insects may contribute to high breeding bird density in structurally diverse habitats. Heavy use of wet/flooded tundra by late summer migrants probably reflects abundance of midge (Diptera: chironomidae) larvae in pond sediments.