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Jean-françois Giroux - One of the best experts on this subject based on the ideXlab platform.
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Density‐dependent effects on Nesting Success of temperate‐breeding Canada geese
Journal of Avian Biology, 2014Co-Authors: Anik Pannetier Lebeuf, Jean-françois GirouxAbstract:Density-dependent effects on reproduction can arise through variation in habitat quality or increased competition and interference among neighbours. Negative effects have been found in avian populations and these have been mainly attributed to food limitations. In this study, we investigated whether density-dependent effects could result from either heterogeneity in habitat suitability, interference among neighbours, or predation. To test these hypotheses, we collected data over eight years in a growing population of temperate-Nesting Canada geese Branta canadensis maxima. We compared different parameters of Nesting Success of geese between two sites characterized by different nest densities and looked at the effects of nest proximity on these parameters within each site. At the landscape level, we found density-dependent effects due to variation in habitat quality associated with predation probabilities and flooding events. At a finer scale, Nesting Success declined with proximity to neighbours, probably due to increased aggressive interactions among pairs. However, complete clutch predation showed both positive and negative density-dependence, due to differences in predator community at each site. We concluded that density-dependent effects reduced Nesting Success of Canada geese through both heterogeneity in habitat safety and agonistic interference between neighbours but that density-dependent effects could also be positive in some instances.
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a link between water availability and Nesting Success mediated by predator prey interactions in the arctic
Ecology, 2009Co-Authors: Nicolas Lecomte, Gilles Gauthier, Jean-françois GirouxAbstract:Although water availability is primarily seen as a factor affecting food availability (a bottom-up process), we examined its effect on predator-prey interactions through an influence on prey behavior (a top-down process). We documented a link between water availability, predation risk, and reproductive Success in a goose species (Chen caerulescens atlantica) inhabiting an Arctic environment where water is not considered a limited commodity. To reach water sources during incubation recesses, geese Nesting in mesic tundra (low water availability) must move almost four times as far from their nest than those Nesting in wetlands, which reduced their ability to defend their nest against predators and led to a higher predation rate. Nesting Success was improved in high rainfall years due to increased water availability, and more so for geese Nesting in the low water availability habitat. Likewise, Nesting Success was improved in years where the potential for evaporative water loss (measured by the atmospheric water vapor pressure) was low, presumably because females had to leave their nest less often to drink. Females from water-supplemented nests traveled a shorter distance to drink, and their Nesting Success was enhanced by 20% compared to the control. This shows that water availability and rainfall can have a strong effect on predator-prey dynamics and that changes in precipitation brought by climate change could have an impact on some Arctic species through a top-down effect.
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A link between water availability and Nesting Success mediated by predator–prey interactions in the Arctic
Ecology, 2009Co-Authors: Nicolas Lecomte, Gilles Gauthier, Jean-françois GirouxAbstract:Although water availability is primarily seen as a factor affecting food availability (a bottom-up process), we examined its effect on predator-prey interactions through an influence on prey behavior (a top-down process). We documented a link between water availability, predation risk, and reproductive Success in a goose species (Chen caerulescens atlantica) inhabiting an Arctic environment where water is not considered a limited commodity. To reach water sources during incubation recesses, geese Nesting in mesic tundra (low water availability) must move almost four times as far from their nest than those Nesting in wetlands, which reduced their ability to defend their nest against predators and led to a higher predation rate. Nesting Success was improved in high rainfall years due to increased water availability, and more so for geese Nesting in the low water availability habitat. Likewise, Nesting Success was improved in years where the potential for evaporative water loss (measured by the atmospheric water vapor pressure) was low, presumably because females had to leave their nest less often to drink. Females from water-supplemented nests traveled a shorter distance to drink, and their Nesting Success was enhanced by 20% compared to the control. This shows that water availability and rainfall can have a strong effect on predator-prey dynamics and that changes in precipitation brought by climate change could have an impact on some Arctic species through a top-down effect.
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Breeding dispersal in a heterogeneous landscape: the influence of habitat and Nesting Success in greater snow geese
Oecologia, 2008Co-Authors: Nicolas Lecomte, Gilles Gauthier, Jean-françois GirouxAbstract:Despite numerous studies on breeding dispersal, it is still unclear how habitat heterogeneity and previous Nesting Success interact to determine nest-site fidelity at various spatial scales. In this context, we investigated factors affecting breeding dispersal in greater snow geese ( Anser caerulescens atlanticus ), an Arctic breeding species Nesting in two contrasting habitats (wetlands and mesic tundra) with variable pattern of snowmelt at the time of settlement in spring. From 1994 to 2005, we monitored the Nesting Success and breeding dispersal of individually marked females. We found that snow geese showed a moderate amount of nest-site fidelity and considerable individual variability in dispersal distance over consecutive Nesting attempts. This variability can be partly accounted for by the annual timing of snowmelt. Despite this environmental constraint, habitat differences at the colony level consistently affected Nesting Success and settlement patterns. Females Nesting in wetlands had higher Nesting Success than those Nesting in mesic tundra. Moreover, geese responded adaptively to spatial heterogeneity by showing fidelity to their Nesting habitat, independently of snowmelt pattern. From year to year, geese were more likely to move from mesic to high-quality wetland habitat, regardless of previous Nesting Success and without cost on their subsequent Nesting performance. The unpredictability of snowmelt and the low cost of changing site apparently favour breeding-site dispersal although habitat quality promotes fidelity at the scale of habitat patches.
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Are goose Nesting Success and lemming cycles linked? Interplay between nest density and predators
Oikos, 2001Co-Authors: Joël Bêty, Jean-françois Giroux, Gilles Gauthier, Erkki KorpimäkiAbstract:The suggested link between lemming cycles and reproductive Success of arctic birds is caused by potential effects of varying predation pressure (the Alternative Prey Hypothesis, APH) and protective association with birds of prey (the Nesting Association Hypothesis, NAH). We used data collected over two complete lemming cycles to investigate how fluctuations in lemming density were associated with Nesting Success of greater snow geese (Anser caerulescens atlanticus) in the Canadian High Arctic. We tested predictions of the APH and NAH for geese breeding at low and high densities. Goose Nesting Success varied from 22% to 91% between years and the main egg predator was the arctic fox (Alopex lagopus). Nesting associations with snowy owls (Nyctea scandiaca) were observed but only during peak lemming years for geese Nesting at low density. Goose Nesting Success declined as distance from owls increased and reached a plateau at 550 m. Artificial nest experiments indicated that owls can exclude predators from the vicinity of their nests and thus reduce goose egg predation rate. Annual nest failure rate was negatively associated with rodent abundance and was generally highest in low lemming years. This relationship was present even after excluding goose nests under the protective influence of owls. However, nest failure was inversely density-dependent at high breeding density. Thus, annual variations in nest density influenced the synchrony between lemming cycles and oscillations in Nesting Success. Our results suggest that APH is the main mechanism linking lemming cycles and goose Nesting Success and that Nesting associations during peak lemming years (NAH) can enhance this positive link at the local level. The study also shows that breeding strategies used by birds (the alternative prey) could affect the synchrony between oscillations in avian reproductive Success and rodent cycles.
Gilles Gauthier - One of the best experts on this subject based on the ideXlab platform.
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a link between water availability and Nesting Success mediated by predator prey interactions in the arctic
Ecology, 2009Co-Authors: Nicolas Lecomte, Gilles Gauthier, Jean-françois GirouxAbstract:Although water availability is primarily seen as a factor affecting food availability (a bottom-up process), we examined its effect on predator-prey interactions through an influence on prey behavior (a top-down process). We documented a link between water availability, predation risk, and reproductive Success in a goose species (Chen caerulescens atlantica) inhabiting an Arctic environment where water is not considered a limited commodity. To reach water sources during incubation recesses, geese Nesting in mesic tundra (low water availability) must move almost four times as far from their nest than those Nesting in wetlands, which reduced their ability to defend their nest against predators and led to a higher predation rate. Nesting Success was improved in high rainfall years due to increased water availability, and more so for geese Nesting in the low water availability habitat. Likewise, Nesting Success was improved in years where the potential for evaporative water loss (measured by the atmospheric water vapor pressure) was low, presumably because females had to leave their nest less often to drink. Females from water-supplemented nests traveled a shorter distance to drink, and their Nesting Success was enhanced by 20% compared to the control. This shows that water availability and rainfall can have a strong effect on predator-prey dynamics and that changes in precipitation brought by climate change could have an impact on some Arctic species through a top-down effect.
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A link between water availability and Nesting Success mediated by predator–prey interactions in the Arctic
Ecology, 2009Co-Authors: Nicolas Lecomte, Gilles Gauthier, Jean-françois GirouxAbstract:Although water availability is primarily seen as a factor affecting food availability (a bottom-up process), we examined its effect on predator-prey interactions through an influence on prey behavior (a top-down process). We documented a link between water availability, predation risk, and reproductive Success in a goose species (Chen caerulescens atlantica) inhabiting an Arctic environment where water is not considered a limited commodity. To reach water sources during incubation recesses, geese Nesting in mesic tundra (low water availability) must move almost four times as far from their nest than those Nesting in wetlands, which reduced their ability to defend their nest against predators and led to a higher predation rate. Nesting Success was improved in high rainfall years due to increased water availability, and more so for geese Nesting in the low water availability habitat. Likewise, Nesting Success was improved in years where the potential for evaporative water loss (measured by the atmospheric water vapor pressure) was low, presumably because females had to leave their nest less often to drink. Females from water-supplemented nests traveled a shorter distance to drink, and their Nesting Success was enhanced by 20% compared to the control. This shows that water availability and rainfall can have a strong effect on predator-prey dynamics and that changes in precipitation brought by climate change could have an impact on some Arctic species through a top-down effect.
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Breeding dispersal in a heterogeneous landscape: the influence of habitat and Nesting Success in greater snow geese
Oecologia, 2008Co-Authors: Nicolas Lecomte, Gilles Gauthier, Jean-françois GirouxAbstract:Despite numerous studies on breeding dispersal, it is still unclear how habitat heterogeneity and previous Nesting Success interact to determine nest-site fidelity at various spatial scales. In this context, we investigated factors affecting breeding dispersal in greater snow geese ( Anser caerulescens atlanticus ), an Arctic breeding species Nesting in two contrasting habitats (wetlands and mesic tundra) with variable pattern of snowmelt at the time of settlement in spring. From 1994 to 2005, we monitored the Nesting Success and breeding dispersal of individually marked females. We found that snow geese showed a moderate amount of nest-site fidelity and considerable individual variability in dispersal distance over consecutive Nesting attempts. This variability can be partly accounted for by the annual timing of snowmelt. Despite this environmental constraint, habitat differences at the colony level consistently affected Nesting Success and settlement patterns. Females Nesting in wetlands had higher Nesting Success than those Nesting in mesic tundra. Moreover, geese responded adaptively to spatial heterogeneity by showing fidelity to their Nesting habitat, independently of snowmelt pattern. From year to year, geese were more likely to move from mesic to high-quality wetland habitat, regardless of previous Nesting Success and without cost on their subsequent Nesting performance. The unpredictability of snowmelt and the low cost of changing site apparently favour breeding-site dispersal although habitat quality promotes fidelity at the scale of habitat patches.
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Are goose Nesting Success and lemming cycles linked? Interplay between nest density and predators
Oikos, 2001Co-Authors: Joël Bêty, Jean-françois Giroux, Gilles Gauthier, Erkki KorpimäkiAbstract:The suggested link between lemming cycles and reproductive Success of arctic birds is caused by potential effects of varying predation pressure (the Alternative Prey Hypothesis, APH) and protective association with birds of prey (the Nesting Association Hypothesis, NAH). We used data collected over two complete lemming cycles to investigate how fluctuations in lemming density were associated with Nesting Success of greater snow geese (Anser caerulescens atlanticus) in the Canadian High Arctic. We tested predictions of the APH and NAH for geese breeding at low and high densities. Goose Nesting Success varied from 22% to 91% between years and the main egg predator was the arctic fox (Alopex lagopus). Nesting associations with snowy owls (Nyctea scandiaca) were observed but only during peak lemming years for geese Nesting at low density. Goose Nesting Success declined as distance from owls increased and reached a plateau at 550 m. Artificial nest experiments indicated that owls can exclude predators from the vicinity of their nests and thus reduce goose egg predation rate. Annual nest failure rate was negatively associated with rodent abundance and was generally highest in low lemming years. This relationship was present even after excluding goose nests under the protective influence of owls. However, nest failure was inversely density-dependent at high breeding density. Thus, annual variations in nest density influenced the synchrony between lemming cycles and oscillations in Nesting Success. Our results suggest that APH is the main mechanism linking lemming cycles and goose Nesting Success and that Nesting associations during peak lemming years (NAH) can enhance this positive link at the local level. The study also shows that breeding strategies used by birds (the alternative prey) could affect the synchrony between oscillations in avian reproductive Success and rodent cycles.
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Factors Affecting Nesting Success in Greater Snow Geese: Effects of Habitat and Association with Snowy Owls
The Wilson Journal of Ornithology, 1997Co-Authors: Jean-pierre Tremblay, Gilles Gauthier, Denis Lepage, André DesrochersAbstract:examined how habitat features affected Nesting Success of Greater Snow Geese (Chen caerulescens atlantica) on Bylot Island, Northwest Territories, Canada, under high (1993) vs low (1994) Nesting Success and colonial vs isolated Nesting (1994 only). Because Snow Geese nested in association with Snowy Owls (Nyctea scandiuca) in 1993, we also examined the relationship between Nesting Success and distance from owl nests. Predation, especially by Arctic foxes (Alopex lagopus), was the main cause of Nesting failure on Bylot Island. In 1993, goose nests near an owl nest had better Success than those farther away, and they also tended to be initiated earlier. Few habitat features were related to Nesting Success, although nests located in pond habitat had lower Success than those in wet meadows or moist tundra. In 1994, Snowy Owls were absent, and goose Nesting Success was much lower than in 1993 (23-42% vs 90%). Isolated nests located on hillsides had higher Success than those located in lowlands. In contrast, colonial nests were more Successful in lowland wet meadows, where tall willow bushes (Salix Zanata) were present, than in either moist tundra or hillsides. In the latter habitat, nests associated with Cassiope tetragona, a plant that typically grows in depressions between hummocks, had higher Success than those as- sociated with other vegetation. We conclude that Nesting in association with raptors, such as Snowy Owls, that maintain a predator-free area around their nest, was probably a dom- inant factor affecting Greater Snow Goose Nesting Success. In the absence of owls, isolated nests had higher Success in hilly habitats than in lowlands, whereas colonial nests in tall
Nicola Koper - One of the best experts on this subject based on the ideXlab platform.
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Effects of Twice-Over Rotational Grazing on Songbird Nesting Success in Years with and without Flooding
Rangeland Ecology & Management, 2018Co-Authors: Stacey Jalane Carnochan, Christopher Charles De Ruyck, Nicola KoperAbstract:Abstract Rotational grazing is sometimes promoted for grassland bird conservation, but the benefits to wildlife have not been comprehensively documented. We examined effects of twice-over rotational grazing on Nesting Success of grassland songbirds in southwestern Manitoba, Canada in comparison to season-long grazing. We monitored Nesting attempts and collected structural vegetation data in 2011 (during a 1/300 flood event), and 2012 (average water levels), for five species of obligate grassland bird species (n = 110) and one shrub-Nesting species (n = 41). Nesting analyses were conducted using logistic exposure models. Nesting Success was 2.4 to 4 times lower in twice-over grazed pastures compared with season-long grazed pastures, perhaps because of the increased cattle density during the short grazing periods of the twice-over system. Nests protected by shrubs from grazing activities of cattle did not show this pattern. The grazing system did not have an effect on vegetation structure. This suggests that twice-over rotational grazing does not benefit grassland songbirds in northern mixed-grass prairies, and that caution must be taken before implementing this grazing system in areas intended to promote biodiversity conservation.
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Physical footprint of oil and gas infrastructure, not anthropogenic noise, reduces Nesting Success of some grassland songbirds
Biological Conservation, 2016Co-Authors: Jacy Bernath-plaisted, Nicola KoperAbstract:Abstract Western North America's grasslands have undergone a rapid expansion of conventional oil and natural gas development, the effects of which are largely unknown for Nesting songbirds. Understanding mechanisms that drive ecological responses to infrastructure is essential for our ability to identify and minimize potential negative effects on wildlife. Our study sought to distinguish between effects driven by physical structures and those driven by associated anthropogenic noise. Further, we evaluated whether some structure types have smaller ecological footprints than others. We monitored 747 grassland songbird nests, of five species, in Alberta's mixed-grass prairie to determine if, and why, the presence of infrastructure affects Nesting Success. Nesting Success was significantly lower at infrastructure sites relative to controls for both Savannah sparrow ( Passerculus sandwichensis ) and vesper sparrow ( Pooecetes gramineus ), as well as at screwpump relative to pumpjack oil wells. There was no correlation between Nesting Success and noise intensity, and Nesting Success was not significantly lower near roads. However, Nesting Success was lower at electric grid-powered sites relative to generator-powered sites, suggesting that power distribution lines may benefit some nest predators. Vesper sparrow nest density increased with proximity to oil wells and compressor stations, so it is possible that these sites are ecological traps for this species. Management strategies focusing only on reduction of anthropogenic noise and disturbance may be ineffectual for conservation of grassland songbirds. Managers should also seek to reduce the physical footprint of infrastructure on the landscape, replace screwpumps with pumpjacks, and replace grid powered with generator-powered wells.
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Does Management for Duck Productivity Affect Songbird Nesting Success
Journal of Wildlife Management, 2007Co-Authors: Nicola Koper, Fiona K. A. SchmiegelowAbstract:Habitat management for ducks has significantly influenced prairies and wetlands used by other species. However, the effects of management on other species have not been clearly assessed. We present the first study to compare the Nesting Success of ducks with the productivity of coexisting passerines. We evaluated effects of cattle grazing, subdivision of fields, habitat edges, year, and vegetation structure on duck and songbird Nesting Success in 32 mixed-grass prairie fields in southern Alberta, Canada. Duck and songbird Nesting Success were not correlated. Duck Nesting Success was influenced by timing of grazing and vegetation structure, and tended to be higher in wetter years, whereas Nesting Success of most songbirds was not influenced by vegetation structure or grazing, and was sometimes higher in drier years. Local habitat management for ducks cannot be assumed to benefit songbirds. However, some management strategies, such as those that promote tall grass and short litter, might benefit both taxa.
Gregory J Robertson - One of the best experts on this subject based on the ideXlab platform.
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factors affecting nest site selection and Nesting Success in the common eider somateria mollissima
Ibis, 2008Co-Authors: Gregory J RobertsonAbstract:Nesting site selection and Nesting Success in Common Eiders Somateria mollissima were studied over a 3-year period (1991–1993) in the Mast River delta (58o24'N, 94o24'W), 40 km east of Churchill, Manitoba, Canada. Eiders preferentially nested on islands that had incubating Lesser Snow Geese Anser caerulescens caerulescens on them; this effect was also seen between years on the same islands. Eiders which nested on islands with geese had a reduced chance of having eggs taken by predators during egg-laying and had a greater chance of hatching once incubation had begun, independent of the number of other eiders Nesting on the island. The distance to a goose nest was less in nests which did not lose eggs prior to incubation than in those which did, but there was no difference in the distance to a goose nest in eider clutches which did or did not hatch. Artificial eider eggs placed closer to goose nests had a lower probability of being predated than those placed farther away. Nests on islands farther up the river and farther from the mainland had higher Nesting Success, presumably because these Nesting islands were inaccessible to Arctic Foxes Alopex lagopus.
Nicolas Lecomte - One of the best experts on this subject based on the ideXlab platform.
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a link between water availability and Nesting Success mediated by predator prey interactions in the arctic
Ecology, 2009Co-Authors: Nicolas Lecomte, Gilles Gauthier, Jean-françois GirouxAbstract:Although water availability is primarily seen as a factor affecting food availability (a bottom-up process), we examined its effect on predator-prey interactions through an influence on prey behavior (a top-down process). We documented a link between water availability, predation risk, and reproductive Success in a goose species (Chen caerulescens atlantica) inhabiting an Arctic environment where water is not considered a limited commodity. To reach water sources during incubation recesses, geese Nesting in mesic tundra (low water availability) must move almost four times as far from their nest than those Nesting in wetlands, which reduced their ability to defend their nest against predators and led to a higher predation rate. Nesting Success was improved in high rainfall years due to increased water availability, and more so for geese Nesting in the low water availability habitat. Likewise, Nesting Success was improved in years where the potential for evaporative water loss (measured by the atmospheric water vapor pressure) was low, presumably because females had to leave their nest less often to drink. Females from water-supplemented nests traveled a shorter distance to drink, and their Nesting Success was enhanced by 20% compared to the control. This shows that water availability and rainfall can have a strong effect on predator-prey dynamics and that changes in precipitation brought by climate change could have an impact on some Arctic species through a top-down effect.
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A link between water availability and Nesting Success mediated by predator–prey interactions in the Arctic
Ecology, 2009Co-Authors: Nicolas Lecomte, Gilles Gauthier, Jean-françois GirouxAbstract:Although water availability is primarily seen as a factor affecting food availability (a bottom-up process), we examined its effect on predator-prey interactions through an influence on prey behavior (a top-down process). We documented a link between water availability, predation risk, and reproductive Success in a goose species (Chen caerulescens atlantica) inhabiting an Arctic environment where water is not considered a limited commodity. To reach water sources during incubation recesses, geese Nesting in mesic tundra (low water availability) must move almost four times as far from their nest than those Nesting in wetlands, which reduced their ability to defend their nest against predators and led to a higher predation rate. Nesting Success was improved in high rainfall years due to increased water availability, and more so for geese Nesting in the low water availability habitat. Likewise, Nesting Success was improved in years where the potential for evaporative water loss (measured by the atmospheric water vapor pressure) was low, presumably because females had to leave their nest less often to drink. Females from water-supplemented nests traveled a shorter distance to drink, and their Nesting Success was enhanced by 20% compared to the control. This shows that water availability and rainfall can have a strong effect on predator-prey dynamics and that changes in precipitation brought by climate change could have an impact on some Arctic species through a top-down effect.
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Breeding dispersal in a heterogeneous landscape: the influence of habitat and Nesting Success in greater snow geese
Oecologia, 2008Co-Authors: Nicolas Lecomte, Gilles Gauthier, Jean-françois GirouxAbstract:Despite numerous studies on breeding dispersal, it is still unclear how habitat heterogeneity and previous Nesting Success interact to determine nest-site fidelity at various spatial scales. In this context, we investigated factors affecting breeding dispersal in greater snow geese ( Anser caerulescens atlanticus ), an Arctic breeding species Nesting in two contrasting habitats (wetlands and mesic tundra) with variable pattern of snowmelt at the time of settlement in spring. From 1994 to 2005, we monitored the Nesting Success and breeding dispersal of individually marked females. We found that snow geese showed a moderate amount of nest-site fidelity and considerable individual variability in dispersal distance over consecutive Nesting attempts. This variability can be partly accounted for by the annual timing of snowmelt. Despite this environmental constraint, habitat differences at the colony level consistently affected Nesting Success and settlement patterns. Females Nesting in wetlands had higher Nesting Success than those Nesting in mesic tundra. Moreover, geese responded adaptively to spatial heterogeneity by showing fidelity to their Nesting habitat, independently of snowmelt pattern. From year to year, geese were more likely to move from mesic to high-quality wetland habitat, regardless of previous Nesting Success and without cost on their subsequent Nesting performance. The unpredictability of snowmelt and the low cost of changing site apparently favour breeding-site dispersal although habitat quality promotes fidelity at the scale of habitat patches.
