Assessing Climate Change Vulnerability of Breeding Birds in Arctic ...

Snow Goose (Chen Caerulescens)Vulnerability: Presumed StableConfidence: ModerateThe Snow Goose is a common breeder in Arctic Alaska, typically nesting in small, densecolonies scattered near the coast. This species nests on flat tundra, near ponds, shallow lakes,streams, and islands in river deltas (Mowbray et al. 2000). During the breeding season, their dietis primarily vegetarian, eating both aquatic and drier tundra vegetation (Mowbray et al. 2000).For brood rearing, one of the more important habitats is salt affected tundra on islands in riverdeltas (J. Shook, pers. comm.). Most North Slope breeders winter in western North Americafrom British Columbia into California (Mowbray et al. 2000). Current Arctic Coastal Plainpopulation is estimated at approximately 9,000 with an increasing trend (Larned et al. 2012).J. Liebezeit @ WCSRange: We used the extant NatureServe rangemap for the assessment as it closely matched theBirds of North America and other rangedescriptions (Bart et al. 2012, Johnson andHerter 1989).Sea Level Rise & Natural Barriers: Because ofthis its restricted range along coastal areas inArctic Alaska, this species was consideredslightly vulnerable to both sea-level rise and tolimitations in expansion of their range northward(“natural barriers” factor).Physiological Hydro Niche: Snow Geese werescored as particularly vulnerable to changes inhydrologic niche because of their significantassociation with coastal habitats (in particularsalt marsh), ponds, and wet tundra habitats fornesting, foraging, brood-rearing, molting, andavoiding predation. If substantial tundra dryingoccurs, this species could experience aconsiderable negative impact. Currentprojections of annual potential evapotranspirationsuggest negligible atmosphericdrivendrying for the foreseeable future (TWSand SNAP). Thus atmospheric moisture, as anexposure factor (most influential on the“hydrological niche” sensitivity category), wasnot heavily weighted in the assessment.Disturbance Regime: Climate-mediateddisturbances, most importantly increasing storms(Jones et al. 2009) on the coastal plain(including high winds) can back up water andcause the flooding of river deltas. This maydestroy nests that are often less than a meterabove sea level. Breeding densities could declinenearest the coast, but they may be able tosuccessfully nest inland or redistribute to othercolony areas on the coastal plain (J. Shook, pers.comm.).Interactions with Other Species: In terms ofinteractions with other species, it is possible thatred fox nest predation could increase as thispredator’s range expands northward from borealregions (Pamperin et al. 2006). Geese wouldunlikely be able to defend nests as successfullyas against the smaller arctic foxes. Also, climatechanges may disrupt the regularity of the44