North American Brant: effects of changes in habitat and climate on population dynamics

Abstract

We describe the importance of key habitats used by four nesting populations of nearctic brant (Branta bernicla) and discuss the potential relationship between changes in these habitats and population dynamics of brant. Nearctic brant, in contrast to most geese, rely on marine habitats and native intertidal plants during the non-breeding season, particularly the seagrass, Zostera, and the macroalgae, Ulva. Atlantic and Eastern High Arctic brant have experienced the greatest degradation of their winter habitats (northeastern United States and Ireland, respectively) and have also shown the most plasticity in feeding behavior. Black and Western High Arctic brant of the Pacific Flyway are the most dependent on Zostera, and are undergoing a shift in winter distribution that is likely related to climate change and its associated effects on Zostera dynamics. Variation in breeding propensity of Black Brant associated with winter location and climate strongly suggests that food abundance on the wintering grounds directly affects reproductive performance in these geese. In summer, salt marshes, especially those containing Carex and Puccinellia, are key habitats for raising young, while lake shorelines with fine freshwater grasses and sedges are important for molting birds. Availability and abundance of salt marshes has a direct effect on growth and recruitment of goslings and ultimately, plays an important role in regulating size of local brant populations.

Migratory connectivity in Arctic geese: spring stopovers are the weak links in meeting targets for breeding

“…The ability to shift to habitats dominated by agricultural crops differs between the species and season, and recent reviews stress the uncertainties associated with ongoing change (Abraham et al 2005;Gauthier et al 2005;Ward et al 2005;Fox et al 2005;Van Eerden et al 2005). Jefferies et al (2006) point out that current agricultural policy in both North America and Europe will tend to reduce the acreage and quality of crop foods available to geese in winter (and, in many populations, spring as well, see, e.g., Percival and Percival 1997).…”

Long-term climate-associated dynamics of a tropical seagrass meadow: implications for the future

“…Existing 20th century global climate change of 0.6 ± 0.2°C has already resulted in significant ecological changes across an expanse of different ecosystems and ecological hierarchies (McCarty 2001, Walther et al 2002, Ward et al 2005, Hoegh-Guldberg et al 2007, Prezeslawski et al 2008. These responses are expected to accelerate, resulting in habitat degradation, species loss and range changes caused by increases in temperature (McCarty 2001, Poloczanska et al 2007, storm frequency and intensity (Harley et al 2006, Crabbe et al 2008) and acidification of aquatic environments (Kleypas et al 1999, Orr et al 2005.…”

Normalized Difference Vegetation Index as an Estimator for Abundance and Quality of Avian Herbivore Forage in Arctic Alaska

“…The halophytic graminoid wetlands on the ACP are widely distributed, and to date, grazing by geese has had little effect on productivity of these wetlands, indicating that they can likely support further increases in goose populations [8]. Knowing how biomass and nutrient quality of forage plants varies seasonally and annually is necessary to predictlong-term outcomes for these migratory avian herbivores [7].…”

“…Halophytic graminoid wetlands provide high quality foods that are important for the reproductive success of three migratory avian herbivores on the ACP, lesser snow geese (Chen caerulescens caerulescens; hereafter snow geese), greater white-fronted geese (Anser albifrons frontalis; hereafter white-fronted geese), and black brant (Branta bernicla nigricans; hereafter brant) [7,8]. These wetlands contain plants that are high in nitrogen, a critical nutrient for the rapid growth of goslings during the short arctic summers.…”