This paper highlights the impacts that hyperabundant herbivores can have on tundra habitats and sympatric-nesting species.
In this study Scott Flemming and colleagues examined how grazing and grubbing by a lesser snow (Chen caerulescens) and Ross’ goose (Chen rossii) colony influenced the availability and quality of habitats selected by eight different shorebird species in the eastern Canadian Arctic.
During randomly selected habitat surveys conducted at three study sites that varied in goose presence and influence (High, Moderate, Low), they estimated the proportional contribution of difference habitat types, amount of lateral concealment provided, and measured the height of various cover types (e.g. grasses, rock, willow). They also searched for shorebird nests at plots situated within each study site and conducted habitat surveys at all shorebird nests. At random sites, the availability of sedge meadow was negatively related to increasing goose influence while the availability of exposed sediment was positively related. The amount of lateral concealment provided by cover types was also negatively related to increasing goose influence and this trend was largely driven by changes in sedges and grasses. The densities of cover-nesting shorebirds (species that prefer nesting in sedge meadow habitat that provides high concealment) were lowest at the High goose influence site and highest at the Low goose influence site. Furthermore, cover-nesting shorebirds at the Moderate goose influence site selected nest sites with less sedge meadow and concealment than those at the Low goose influence site. Many shorebirds select nesting habitats that provide them with high concealment from predators; the authors therefore suggest that goose-induced habitat alteration may not only be influencing shorebird nest site selection, but also nest survival probability and recommend more research in this field.
This study demonstrates how habitat alteration by hyperabundant populations of geese can influence nest site selection of Arctic shorebirds at multiple scales and highlights the importance of goose population management.
Reference: Flemming, S.A., Nol, E., Kennedy, L.V., Smith, P.A. (2019) Hyperabundant herbivores limit habitat availability and influence nest site selection of Arctic‐breeding birds. Journal of Applied Ecology
https://doi.org/10.1111/1365-2664.13336
You can read the full article here.
Picture: Foraging Lesser snow goose (Chen caerulescens) in Nunavut (photo credit: Scott Flemming, Trent University)