Noel et al. (2004) claimed that oil development on Alaska's North Slope has not adversely affected caribou (Rangifer tarandus) distribution. Their argument was based on the lack of statistical difference between caribou densities at different distances from the Milne Point road, Prudhoe Bay, Alaska, USA, 10-20 years after its construction. Our primary criticisms of that article are that the authors failed to include the effects of expanding oilfield infrastructure in their analysis, to incorporate 6 of 13 surveys, and to discuss data that revealed caribou largely abandoned their study area following this development. After the construction of the road, calving caribou were displaced from a previously used zone 0-4 km from the road, which subsequently increased use 4-6 km away from the road in the years spanning 1982-1987. With additional development of roads and pads in the calving grounds after 1987, affecting 92% of the study area, the remaining undisturbed fragments were too small for continued use of the area for concentrated calving. Our analysis of the Noel et al. data shows an overall gradual abandonment of the oilfield during calving and a drop in abundance of calving caribou by at least 72% within the oilfield, in spite of the fact that the total herd size had increased 4- to 5-fold during that time period. The major concentration of calving shifted to south of the oilfield, whereas such shifts in calving did not occur in the eastern portion of the Central Arctic Herd that was less affected by development.

Tags: Alaska caribou