Resource partitioning in sympatric arctic‐breeding geese: summer habitat use, spatial and dietary overlap of Barnacle and Pink‐footed Geese in Svalbard

Abstract

The spatial, habitat and dietary overlap of two breeding goose species was studied in Sassendalen, Svalbard, in summer 2003 based on abundance within 500 × 500‐m grid squares and faecal diet analyses during pre‐breeding, nesting and post‐hatching periods. More than half of all Pink‐footed Geese Anser brachyrhynchus occurred in the absence of Barnacle Geese Branta leucopsis during nesting and post‐hatching periods compared to c. 20% when concentrated by pre‐breeding snow cover. In contrast, only 5% of Barnacle Geese were observed in the absence of Pink‐footed Geese pre‐breeding, 15% during nesting, and 35% post‐hatching. Among six defined habitat types, Barnacle Geese resorted more to ‘upland’ habitats during pre‐breeding and nesting and to lowland lakes post‐hatching when compared to Pink‐footed Geese. Although Pink‐footed Geese showed less change in seasonal habitat preference, many shifted to the river valley bottom post‐hatching, giving access to open water (predator avoidance) and lush green vegetation (foraging for goslings). The smallest extent of distributional overlap between the two species occurred post‐hatching, but each species was also highly restricted by snow cover during pre‐nesting. The greatest extent of overlap in distribution and diet occurred during incubation, when large dietary variation between different breeding valleys reflected local food availability around nests (probably a result of nest‐site preference rather than food selection per se). Whether this means that increased interactions within and between the two goose species with future increases in local density are most likely to be manifest at this stage of the summer is impossible to determine without knowledge of available food resources and manipulative experiments. More detailed investigations of the effects of foraging by both species on plant structure, quality and community composition are necessary to predict likely outcomes of future changes in population densities of both species.

Reproductive responses to spatial and temporal prey availability in a coastal Arctic fox population

“…The breeding of geese in our study area is restricted to inland river canyons and terrain that give protection from predation (Wisz et al. 2008; Fox et al. 2009).…”

Effects of disturbance on geese in Svalbard: implications for regulating increasing tourism

“…The present distribution seems to be limited by the length of the frost-free period during summer (Jensen et al 2008). After hatching, families feed in lowland marshes and moss fens, under bird cliffs, and often move far inland, away from open water (Jepsen et al 2002;Fox et al 2007;Fox et al 2009;Madsen unpubl. data).…”

“…In contrast, pink‐footed geese often feed far inland, and will not seek protection on lakes; instead, they run inland, towards the river (in Sassendalen; Fox et al. 2007; Fox et al. 2009) or retreat to the sea.…”

Spatial patterns of goose grubbing suggest elevated grubbing in dry habitats linked to early snowmelt

“…Most of these populations have increased significantly over the last few decades due to conservation efforts, intensified agricultural practices and a warmer climate (Abraham et al 2005;Fox et al 2005;Kery et al 2006;Bauer et al 2008;Fox et al 2010). The Arctic tundra is therefore linked to European land use and conservation policies and management strategies for migrating goose populations.…”