Conversion of tundra to exposed peat habitat by snow geese (Chen caerulescens caerulescens) and Ross’s geese (C. rossii) in the central Canadian Arctic

Conkin, John Alexander; Alisauskas, Ray T.

doi:10.1007/s00300-016-1979-x

Cited by 18 publications

(33 citation statements)

References 14 publications

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“…Similar landscape‐level changes induced by grubbing and grazing of graminoids by geese have been reported elsewhere. In the Queen Maud Gulf region, Canada, the proportion of exposed peat increased significantly with proximity to goose colonies (Conkin & Alisauskas, ) and the biomass of graminoids was 330 g/m 2 lower within colonies compared to outside (Samelius & Alisauskas, ). Over ~23 years, satellite imagery shows that the proportion of exposed substrate present in the Queen Maud Gulf region increased by 410%, which resulted in a ~32% decline in wet sedge meadow, particularly within the goose colony (Conkin & Alisauskas, ).…”

Section: Discussionmentioning

confidence: 99%

“…In the Queen Maud Gulf region, Canada, the proportion of exposed peat increased significantly with proximity to goose colonies (Conkin & Alisauskas, ) and the biomass of graminoids was 330 g/m 2 lower within colonies compared to outside (Samelius & Alisauskas, ). Over ~23 years, satellite imagery shows that the proportion of exposed substrate present in the Queen Maud Gulf region increased by 410%, which resulted in a ~32% decline in wet sedge meadow, particularly within the goose colony (Conkin & Alisauskas, ). In the Hudson Bay lowlands, goose‐altered areas have 29% more bare ground, 30% more moss and 32% less sedge cover than intact areas (Sammler et al., ), and grazing geese have reduced the proportions of sedge (−37%) and scrub habitat (−61%; Peterson, Rockwell, Witte, & Koons, ).…”

Section: Discussionmentioning

confidence: 99%

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Hyperabundant herbivores limit habitat availability and influence nest site selection of Arctic‐breeding birds

Flemming

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Kennedy

et al. 2019

Journal of Applied Ecology

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Understanding an organism's habitat selection and behavioural flexibility in the face of environmental change can help managers plan for future conservation of that species. Hyperabundant tundra‐nesting geese are influencing Arctic environments through their foraging activities. Goose‐induced habitat change in Arctic wetlands may influence the availability of habitat for numerous shorebird species that breed sympatrically with geese. We explore whether goose‐induced habitat alteration affects shorebird breeding density and nest site selection. Using habitat data collected at sites with High, Moderate and Low goose influence, and samples collected during two periods separated by 11 years, we document the habitat characteristics influenced by geese. We describe the habitat characteristics preferred by shorebirds and relate their availability to goose influence and shorebird density. Finally, we examine whether shorebird nest site selection has changed over time and whether shorebirds select nest sites differently in habitat influenced by geese. We document spatial and temporal changes in sedge meadow habitat and lateral concealment relating to goose influence. The availability of sedge meadow habitat and the degree of lateral concealment declined with increasing goose influence, and also declined at two sites over the 11 years of the study. Densities of both cover‐ and open‐nesting shorebirds were highest where goose influence was lowest. At sites with Low goose influence, cover‐nesting shorebirds selected nest sites with more sedge meadow and concealment than at sites with Moderate and High goose influence, presumably because these high‐quality sites were more available. Synthesis and applications. Intensive foraging by a colony of hyperabundant geese is limiting the availability of preferred nesting habitat and densities of sympatric‐nesting shorebirds. Where goose‐induced habitat alteration is pronounced shorebird species that select concealed nest sites are nesting in areas with lower concealment and less sedge meadow. Studies examining the degree to which these effects scale up to impact the population sizes of declining shorebirds should be considered a future research priority. Moreover, management strategies for geese should incorporate the habitat needs of sympatric species and reinvigorate efforts for goose population reduction in order to achieve the population targets articulated by management agencies.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Hyperabundant herbivores limit habitat availability and influence nest site selection of Arctic‐breeding birds

Flemming

Nol

Kennedy

et al. 2019

Journal of Applied Ecology

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“…To isolate the effects of geese per se, we excluded from analysis any plots that were >200 km from the edge of a known goose colony. Previous site‐specific studies have found goose‐related effects on vegetation extend 17–19 km (Conkin and Alisauskas ; R. F. Rockwell et al., unpublished data ) from colonies, while effects on predators extend to 10.5 km from colonies (Lamarre et al. ).…”

Section: Methodsmentioning

confidence: 92%

“…In the analyses, we examined patterns within this 200 km buffer in an attempt to locate a threshold distance for effects of geese (see Data analyses ). We acknowledge that pre‐ and post‐breeding light geese can have pronounced effects on habitat far outside the boundaries of the breeding colonies (Conkin and Alisauskas ). Thus, some of our plots outside of colonies were nevertheless within areas of altered habitat, weakening our ability to test our prediction and making our approach a conservative test of the effects of geese.…”

Section: Methodsmentioning

confidence: 99%

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Broad‐scale changes in tundra‐nesting bird abundance in response to hyperabundant geese

et al. 2019

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Environmental changes can propagate through food webs in complex ways via trophic cascades. In the North American Arctic, hyperabundant populations of geese are causing significant habitat change and the resulting trophic cascades are known to impact plant and invertebrate communities. However, the potential impacts on other tundra‐nesting birds are not fully understood. Here, we evaluate the impacts of light geese (Snow Geese, Chen caerulescens, and Ross’ Goose, Chen rossii) populations on other tundra‐nesting birds, using count data collected during bird surveys conducted at varying distances from light goose colonies across the Canadian Arctic. From a dataset of 920 12–16 ha plots distributed across the Canadian Arctic, we identified 527 that were within 200 km of the mapped extent of known light goose colonies. After accounting for regional variation, we demonstrate that densities of most Cover‐Nesting Shorebirds and passerines are depressed in the vicinity of light goose colonies. We suggest that these trends are the results of the combined effects of goose‐induced changes in habitat and predator–prey interactions. These direct and indirect effects of light geese could be contributing to the declines experienced by some tundra‐nesting bird populations in parts of their range. Ongoing climate‐related changes to habitat, predators, and arthropods could interact with this effect of geese to further alter the suitability of tundra habitats for Arctic‐breeding birds, in additive or even unanticipated ways.

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Reduction in biomass of freshwater arctic vegetation by foraging and nesting hyperabundant herbivores shows recovery

Kellett

Alisauskas

2022

Ecosphere

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Arctic‐nesting geese are specialist herbivores of grasses and sedges (collectively, graminoids). Under moderate grazing pressure, these migratory herbivores can create and maintain arctic grazing lawns with high nutritional content and low aboveground biomass. Nutrient and energy subsidies from southern agricultural landscapes during winter have improved survival among populations of Ross's (Anser rossii) and lesser snow geese (Anser caerulescens caerulescens), leading to marked population growth. Resulting goose hyperabundance has raised conservation concern for resilience of arctic ecosystems to withstand cumulative and intense pressures of herbivory and nest construction. We used both design‐based (experimental herbivore exclosures) and model‐based methods to investigate changes to plant community structure in direct response to foraging and nesting by these species within the Queen Maud Gulf (Ahiak) Migratory Bird Sanctuary, Nunavut, Canada. Annual nest construction and foraging by up to ~1.3 million geese at a large colony at Karrak Lake markedly reduced aboveground biomass of forage (graminoids) and non‐forage (foliose and fruticose lichens) vegetation, with spatial variation in reduction associated with intensity of use by geese. Within vast brood‐rearing regions, foraging reduced above‐ and belowground plant biomass of lowland plant communities by 61% and 29%, respectively, between 1994 (when herbivore exclosures were established) and 2017. In addition to landscape diversity associated with abiotic properties created by geomorphic processes, long‐term herbivory by geese further increased spatial heterogeneity in vegetation at the landscape scale. Although foraging geese nearly completely depleted aboveground plant biomass in some parts of their brood‐rearing areas, belowground biomass was largely conserved, and thus, plant communities had strong potential for aboveground regeneration. We propose that the effects of high‐density nesting and foraging by Ross's and lesser snow geese in the central Canadian Arctic, while extensive, are ephemeral and prone to reversion following cessation of grazing and nesting pressure, such as that afforded by shifts in herbivore distribution or local population decline.

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Conversion of tundra to exposed peat habitat by snow geese (Chen caerulescens caerulescens) and Ross’s geese (C. rossii) in the central Canadian Arctic

Cited by 18 publications

References 14 publications

Hyperabundant herbivores limit habitat availability and influence nest site selection of Arctic‐breeding birds

Hyperabundant herbivores limit habitat availability and influence nest site selection of Arctic‐breeding birds

Broad‐scale changes in tundra‐nesting bird abundance in response to hyperabundant geese

Reduction in biomass of freshwater arctic vegetation by foraging and nesting hyperabundant herbivores shows recovery

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