Summer ecology of the Teshekpuk caribou herd

Abstract

The summer range of the Teshekpuk Caribou (Rangifer tarandus granti) Herd is currently undergoing the initial stages of petroleum exploration and development. Pre-development baseline information is necessary to interpret post-development distribution and habitat selection of caribou and to develop mitigation measures. We estimated bi-weekly distributions, diet and habitat selection by caribou during the summers, 2002-2004, based on aerial relocations of 21-49 radio-collared females. Little or no habitat selection was detected when comparing used locations to habitat available within bi-weekly utilization distributions. Habitat selection was much stronger when comparing bi-weekly utilization distributions to the remaining area of summer use. At the latter scale of analysis, there were dynamic temporal patterns in resource selection by caribou. High air temperature was strongly avoided throughout July. Tussock tundra was avoided early in the summer, but selected during August. Wet sedge was selected in June and from late-August through September. Estimates of dietary nitrogen content indicated that high nitrogen concentrations are available only for a short period in early summer, and declined well before forage biomass. Predicted dietary nitrogen concentration appeared to be much lower for the Teshekpuk Caribou Herd than for the Porcupine Caribou Herd. Successful mitigation measures for petroleum development in NPR-A will need to be spatially and temporally tailored to observed dynamic patterns in caribou resource selection. Future work should estimate the performance of caribou (e.g., survival or weight gain) in relation to habitat quality and use in order to confirm the value of selected habitats and to enhance the robustness of mitigation measures.