Habitat selection by calving caribou of the Central Arctic Herd, 1980-95

Abstract

Habitat selection by calving caribou (Rangifer tarandus granti) of the Central Arctic Herd, Alaska, was assessed in relation to distance from roads, vegetation type, relative plant biomass (NDVI; Normalized Difference Vegetation Index), accumulation of plant biomass during early lactation (NDVIrate), snow cover, and terrain ruggedness. From 183 calving sites of 96 radio collared- females, 1980-95, calving distribution was estimated in reference (no development) and treatment (oilfields present) zones east and west of the Sagavanirktok River, respectively. In the reference zone, caribou regularly selected wet-graminoid vegetation, above-median NDVIrate, and non-rugged terrain; concentrated calving remained in habitats with zonal average NDVI on 21 June (NDVI621). In the treatment zone, selection patterns were inconsistent; concentrated calving shifted inland to rugged terrainwith low NDVI621 and away from development. Repeated use of lower-quality habitats in the treatment zone could compromise nutrient intake by calving females, thereby depressing reproductive success of the western-segment of the herd.