Caribou Use of Narrow Land Corridors around Teshekpuk Lake, Alaska

We used 17 years of satellite- and GPS-collar location data to investigate how 2 narrow land areas constricted movement of the Teshekpuk Caribou Herd around Teshekpuk Lake in northern Alaska. In the future, the oil industry may build pipelines in one or both of these constricted zones, identified as the Smith Area (northwest of the lake) and the Kogru Area (east of the lake). To mitigate impacts of pipelines on caribou movements, we need pre-development movement data to understand how caribou use these corridors in the absence of pipelines. Caribou used the areas most extensively during summer, especially in early July, when at least 73% of collared caribou accessed the area north of the lake through one or both narrow corridors. The proportion of collared caribou was consistently higher in the Kogru Area than in the Smith Area. A slightly higher proportion of caribou moved north across the Smith Area than moved south, while a higher proportion moved south across the Kogru Area than moved north. This resulted in a tendency for a clockwise movement around the lake. Weather patterns and caribou behavior during mosquito season may explain this pattern. The proportion of satellite-collared caribou moving across the constricted zones varied widely among years—from 14% to 83% for the Smith Area and from 17% to 77% for the Kogru Area. Caribou movements were slowest in June and most rapid in July, when caribou movements were also more rapid in the constricted zones than on either side of them. Although GPS-collar data provide more extensive and accurate information than satellite-collar data, some of the trends observed from GPS-collar data in this study were relatively weak due to the small sample size. The BLM needs to stay engaged in the collection of those data and require an updated analysis before approving any future pipelines through one or both constricted zones.