Evaluating the Potential Impact of a Gas Pipeline on Whimbrel Breeding Habitat in the Outer Mackenzie Delta, Northwest Territories

We used ground surveys to identify breeding habitat for Whimbrel (Numenius phaeopus) in the outer Mackenzie Delta, Northwest Territories, and to test the value of high-resolution IKONOS imagery for mapping additional breeding habitat in the Delta. During ground surveys, we found Whimbrel nests (n = 28) in extensive areas of wet-sedge low-centered polygon (LCP) habitat on two islands in the Delta (Taglu and Fish islands) in 2006 and 2007. Supervised classification using spectral analysis of IKONOS imagery successfully identified additional areas of wet-sedge habitat in the region. However, ground surveys to test this classification found that many areas of wet-sedge habitat had dense shrubs, no standing water, and/or lacked polygon structure and did not support breeding Whimbrel. Visual examination of the IKONOS imagery was necessary to determine which areas exhibited LCP structure. Much lower densities of nesting Whimbrel were also found in upland habitats near wetlands. We used habitat maps developed from a combination of methods, to perform scenario analyses to estimate the potential effects of the Mackenzie Gas Project on Whimbrel habitat. Assuming effective complete habitat loss within 20 m, 50 m, or 250 m of any infrastructure or pipeline, the currently proposed pipeline development would result in loss of 8%, 12%, or 30% of existing Whimbrel habitat. If subsidence were to occur, most Whimbrel habitat could become unsuitable. If the facility is developed, follow-up surveys will be required to test these models.

Reproductive Consequences of Nest Site Use in Fork-tailed Storm-Petrels in the Aleutian Islands, Alaska: Potential Lasting Effects of an Introduced Predator

We examined the reproductive consequences of differential nest site use in Fork-tailed Storm-Petrels (Oceanodroma furcata) in the Aleutian Islands, Alaska, where birds on islands where foxes were introduced nest in rocky substrate rather than in typical soil habitat. We investigated how physical and microclimatic nest site characteristics influenced storm-petrel breeding success 20 years after fox removal. We then examined whether those nest site characteristics that affected success were related to the amount of rock that composed the nest. In both years of our study, nest temperature had the strongest influence on chick survival and overall reproductive success, appearing in all the top models and alone explaining 14–35% of the variation in chick survival. The relationship between reproductive success and nest temperature was positive in both years, with higher survival in warmer nests. In turn, the best predictor of nest temperature was the amount of rock that composed the site. Rockier nests had colder average temperatures, which were driven by lower daily minimum temperatures, compared to nests with more soil. Thus, the rockiness of the nest site appeared to affect chick survival and overall reproductive success through its influence on nest temperature. This study suggests that the use of rocky nest sites, presumed to be a result of historic predation from introduced foxes, could decrease breeding success in this recovering population, and thus be a long-lasting effect of introduced predators.