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

Cackling/Canada Goose (Branta hutchinsii / canadensis)Vulnerability: Presumed StableConfidence: HighCackling and Canada Geese were recently split into two species. The Cackling Goose tavernerisubspecies is thought to be the dominant breeder on Alaska’s Arctic Coastal Plain although someevidence suggests they may interbreed with Canada Goose parvipes subspecies (Mowbray et al.2002). Coastal plain Cackling/Canada geese nest in moist sedge shrub tundra with brood rearingin wet sedge meadows, often near the coast (Mowbray et al. 2002). On the coastal plain their dietis dominated by Carex spp. (J. Hupp, pers. comm.). Arctic Alaskan populations winter primarilyin w. Washington and Oregon as well as n. California (Mowbray et al. 2002). The AlaskanArctic Coastal Plain population is estimated at ~8,000 with a stable population (Larned et al.2012).S. Zack @ WCSRange: We used the extant NatureServe map forthe assessment as it matched the Birds of NorthAmerica range description (Mowbray et al.2002). It should be noted that most birds occurnear Teshekpuk Lake (J. Hupp, pers. comm.).Physiological Hydro Niche: Reliance onparticular hydrologic conditions was ranked asthe greatest potential source of vulnerability forthe Cackling/Canada geese. This response wasdriven primarily by this species close associationwith moist/wet sedge communities and largelakes for both nesting and foraging. A dryingtrend could have negative impacts by reducingavailability of suitable habitats. 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.Human Response to CC: All-weather roads(necessitated by a warming climate andshortened ice road season) associated withenergy extraction activities could impactbreeding and molting habitats, particularly nearTeshekpuk Lake. However, combined sources ofhuman activity related to climate changemitigation will likely be minimal and localizedin the near future.Physiological Thermal Niche: Because thisspecies is distributed across a broad thermalrange in North America they are likely notimpacted or could benefit from warmingtemperatures, reducing stress related to earlyseason cold temperatures.Disturbance Regime: Climate-mediateddisturbance processes, namely thermokarst,could both create and destroy foraging andnesting habitats through both ice wedgedegradation and draining of thaw lakes (Martinet al. 2009). Likewise, predicted increasedcoastal erosion and resulting salinization (Joneset al. 2009) could both negatively and positivelyaffect nesting and staging birds by destroyingand creating nesting, foraging, and moltinghabitats.Dietary Versatility: Because this speciescomplex relies so heavily on Carex spp. as a dietsource, any reduction in this food source relatedto climate could have negative consequences.Genetic Variation: Current mitochondrial DNAevidence suggests Cackling/Canada geese have48