Trends in Abundance of Collared Lemmings Near Cape Churchill, Manitoba, Canada

Reiter, Matthew E.; Andersen, David E.

doi:10.1644/07-mamm-a-046.1

Cited by 7 publications

(8 citation statements)

References 28 publications

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“…We did not observe large fluctuations in rodent densities between 2010 and 2013, which were consistently much lower than the peak density observed in 1994 (Roth 2002). The last lemming peak on record in the Churchill area was in 2003 (Reiter & Andersen 2008), but we found no record of lemming abundance from 2005 to 2009. During periods of low lemming densities, Arctic foxes increase predation on nesting geese and shorebirds (Bêty et al 2002;Meltofte et al 2007) and reduce nesting success (Nolet et al 2013).…”

Section: Discussioncontrasting

confidence: 58%

Goose persistence in fall strongly influences Arctic fox diet, but not reproductive success, in the southern Arctic

2017

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Food availability is the primary limitation for terrestrial Arctic predators, many of which rely on rodents that fluctuate in abundance over a 3-5-year period. During rodent scarcity, predators such as Arctic foxes (Vulpes lagopus) consume alternative prey, such as migratory birds, which are plentiful during summer. In most of the Arctic these birds return south by August, but in northern Manitoba, near the southern edge of the Arctic fox distribution, large numbers of lesser snow geese (Chen caerulescens caerulescens) and Canada geese (Branta canadensis interior) persist into October. This extended availability of geese late into fall may reduce the dependence of Arctic foxes on rodents. We used stable isotope and faecal analyses to reconstruct the Arctic fox fall and winter diet and related the most probable contributions of lemmings, goose eggs and juvenile geese with changes in prey availability and fox reproduction. Geese were a potentially important component of the fall diet for Arctic foxes, especially in years with high goose productivity, but rodents were the main component of the diet in late winter, even though rodents were scarce each summer (2010)(2011)(2012)(2013). Furthermore, rodent density had a greater influence on Arctic fox reproduction, which was correlated with the subsequent winter harvest, than any other variable examined. Although geese were important fall prey for Arctic foxes at the southern edge of their distribution, they did not buffer declines in availability of rodents, which were the primary prey in April when food availability is critical for Arctic fox reproduction.

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Section: Discussioncontrasting

confidence: 58%

Goose persistence in fall strongly influences Arctic fox diet, but not reproductive success, in the southern Arctic

2017

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“…Similarly, the bears co-occur with caribou, whose numbers have increased substantially since the 1960s and that have expanded their summer range closer toward the coast [ 62 ], where interactions with arriving polar bears are common (unpublished observation). Other prey, such as rodents, are less mobile but are common in upland habitat, occurring within 5 km from the coast in years when they are abundant [ 63 , 64 ].…”

Section: Discussionmentioning

confidence: 99%

Dietary composition and spatial patterns of polar bear foraging on land in western Hudson Bay

Gormezano

Rockwell

2013

BMC Ecol

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BackgroundFlexible foraging strategies, such as prey switching, omnivory and food mixing, are key to surviving in a labile and changing environment. Polar bears (Ursus maritimus) in western Hudson Bay are versatile predators that use all of these strategies as they seasonally exploit resources across trophic levels. Climate warming is reducing availability of their ice habitat, especially in spring when polar bears gain most of their annual fat reserves by consuming seal pups before coming ashore in summer. How polar bears combine these flexible foraging strategies to obtain and utilize terrestrial food will become increasingly important in compensating for energy deficits from lost seal hunting opportunities. We evaluated patterns in the composition of foods in scat to characterize the foraging behaviors that underpin the diet mixing and omnivory observed in polar bears on land in western Hudson Bay. Specifically, we measured diet richness, proportions of plant and animal foods, patterns in co-occurrence of foods, spatial composition and an index of temporal composition.ResultsScats contained between 1 and 6 foods, with an average of 2.11 (SE = 0.04). Most scats (84.9%) contained at least one type of plant, but animals (35.4% of scats) and both plants and animals occurring together (34.4% of scats) were also common. Certain foods, such as Lyme grass seed heads (Leymus arenarius), berries and marine algae, were consumed in relatively higher proportions, sometimes to the exclusion of others, both where and when they occurred most abundantly. The predominance of localized vegetation in scats suggests little movement among habitat types between feeding sessions. Unlike the case for plants, no spatial patterns were found for animal remains, likely due the animals’ more vagile and ubiquitous distribution.ConclusionsOur results suggest that polar bears are foraging opportunistically in a manner consistent with maximizing intake while minimizing energy expenditure associated with movement. The frequent mixing of plant-based carbohydrate and animal-based protein could suggest use of a strategy that other Ursids employ to maximize weight gain. Further, consuming high rates of certain vegetation and land-based animals that may yield immediate energetic gains could, instead, provide other benefits such as fulfilling vitamin/mineral requirements, diluting toxins and assessing new foods for potential switching.

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“…Lemming Abundance.-We used relative lemming abundance estimated by Reiter and Andersen (2008b) for Nestor One between 1992 and 2004 to identify years with lemming population peaks and trough years, 1 year following a peak. Reiter and Andersen (2008b) adapted methods described by Danell et al (1999) to generate a relative measure of lemming abundance.…”

Section: Methodsmentioning

confidence: 99%

“…Reiter and Andersen (2008b) adapted methods described by Danell et al (1999) to generate a relative measure of lemming abundance. This index was calculated by collecting a random sample of scars on willow (Salix spp.)…”

Section: Methodsmentioning

confidence: 99%

“…Arctic fox depredation accounts for .80% of nest failures in some years (Walter 1996) and local arctic fox dens have been monitored regularly for occupancy. Multi-annual cycles have been documented in collared lemming (Dicrostonyx richardsoni) populations, a primary prey of arctic foxes in this area (Bahr 1989), near the town of Churchill (Shelford 1943, Scott 1993 and more recently at Cape Churchill (Roth 2003, Reiter andAndersen 2008b). However, the extent to which annual fluctuations in nest success of dispersed-nesting EPP Canada Geese coincide with variation in lemming abundance and arctic fox den occupancy is unknown.…”

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confidence: 99%

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Arctic Foxes, Lemmings, and Canada Goose Nest Survival at Cape Churchill, Manitoba

Reiter¹,

Andersen²

2011

The Wilson Journal of Ornithology

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Trends in Abundance of Collared Lemmings Near Cape Churchill, Manitoba, Canada

Cited by 7 publications

References 28 publications

Goose persistence in fall strongly influences Arctic fox diet, but not reproductive success, in the southern Arctic

Goose persistence in fall strongly influences Arctic fox diet, but not reproductive success, in the southern Arctic

Dietary composition and spatial patterns of polar bear foraging on land in western Hudson Bay

Arctic Foxes, Lemmings, and Canada Goose Nest Survival at Cape Churchill, Manitoba

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