The role of forage availability on diet choice and body condition in American beavers (Castor canadensis)

Severud, William J.; Windels, Steve K.; Belant, Jerrold L.; Bruggink, John G.

doi:10.1016/j.mambio.2012.12.001

Cited by 22 publications

(18 citation statements)

References 66 publications

(72 reference statements)

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“…Although aquatic vegetation can constitute a substantial proportion of seasonal and annual beaver diets, it is unknown how abundant aquatic vegetation influences the time beavers spend foraging terrestrially, which may have implications for predation risk of beavers (Severud et al. ).…”

Section: Beavers As Preymentioning

confidence: 99%

The forgotten prey of an iconic predator: a review of interactions between grey wolvesCanis lupusand beaversCastorspp.

Gable

Windels²,

Romanski³

et al. 2018

Mammal Review

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1.Predator-prey relationships can have wide-ranging ecological and landscapelevel effects. Knowledge of these relationships is therefore crucial to understanding how these systems function and how changes in predator-prey communities affect these systems. Grey wolves Canis lupus can be significant predators of beavers Castor spp., and conversely, beavers can be important prey for wolves, but wolf-beaver dynamics in North America, Europe, and Asia are poorly understood. 2. Our objectives were to synthesise current knowledge regarding wolf-beaver interactions and to identify knowledge gaps that should be targeted for study to increase our understanding of wolf-beaver dynamics. 3. During the ice-free season, beavers are vulnerable to predation and can be the primary or secondary prey of wolves, but the factors that affect beaver consumption by wolves are complex and are likely dependent on biological and environmental factors. 4. High beaver abundance can increase wolf pup survival, and beavers may subsidise wolves during periods of reduced ungulate abundance. Thus, many researchers have suggested that beaver densities adversely affect ungulate populations through apparent competition, though this remains largely untested. 5. The effects of wolf predation on beaver population dynamics are poorly understood, as most assessments are lacking in quantitative rigor and are instead based on indirect methods (e.g. scat analysis), anecdotal evidence, or speculation. To understand the effect of predation on beaver populations fully, better estimates (e.g. from documented predation events) of wolf predation on beavers are necessary. 6. Given the complexities of wolf-ungulate-beaver systems, fully understanding wolf-beaver dynamics will be challenging and is likely to require long-term, intensive research of wolf, ungulate, and beaver population parameters.Understanding this dynamic has implications, not only for the conservation and management of wolves and beavers, but also for ungulate populations, which are affected by the numerical and functional responses of wolves in these same systems. Mammal Review ISSN 0305-1838 bs_bs_banner Mammal Review 48 (2018) 123-138

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Section: Beavers As Preymentioning

confidence: 99%

The forgotten prey of an iconic predator: a review of interactions between grey wolvesCanis lupusand beaversCastorspp.

Gable

Windels²,

Romanski³

et al. 2018

Mammal Review

Self Cite

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“…Within lentic environments, aquatic plants are an easily accessible and reliable food source to mammalian herbivores even outside the growing season. For beavers, this aquatic resource requires less search and handling time than woody material on land since the cost of travel to foraging areas and in conveying selected items is reduced due to their buoyancy in water, whilst predation risk is lowered Severud et al, 2013). As yet, no beaver reintroduction programmes have formally considered aquatic vegetation as an important resource or studied any associated foraging behaviours.…”

Section: Introductionmentioning

confidence: 99%

“…), particularly N. alba or its North American equivalent Nymphaea odorata, provides a model system in which to study aquatic foraging behaviour and associated impacts. Lilies are a major component of the vegetation of shallow lakes and ponds in temperate and boreal regions, with leaves, rhizomes and flowers all frequently mentioned in accounts of the diet of beavers (Northcott, 1972;Jenkins, 1980;Roberts & Arner, 1984;Nolet et al, 1994;Severud et al, 2013). The floating blades (henceforth referred to as pads) are typically severed by beavers and then transported to a central place (e.g.…”

Section: Introductionmentioning

confidence: 99%

Beavers and lilies: selective herbivory and adaptive foraging behaviour

Law

Willby

2013

Freshwater Biology

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Summary With the global population of beavers (Castor spp.) increasing, and reintroductions widespread, it is crucial to be able to predict potential impacts on flora and fauna based on defined foraging behaviours. Nymphaea alba (white water lily) is regularly consumed by beavers and provides a model system to test selective foraging behaviour and quantify potential impacts on aquatic resources in standing‐water habitats. Using biometric relationships within N. alba pads, we accurately reconstructed the size and weight of consumed pads, demonstrating that beavers (Castor fiber) selected pads that were significantly larger and heavier than unselected pads. By selecting larger leaves, beavers may also avoid chemical defences associated with anthocyanin pigments that dominate in smaller leaves. Grazing was concentrated in shallow depths (55.7 ± 10.7 cm) close to the shore (2.95 ± 0.62 m) relative to ungrazed plots (100.5 ± 9.2 cm; 4.79 ± 0.68 m). The level of selectivity was unchanged with increasing distance from a central feeding place. Beavers removed 24–50% of pads within grazed areas, but relative to the whole N. alba leaf pad resource, the impact of this foraging was low (0.38–1.23% loss). Plant species diversity was unaffected by foraging, and there was no evidence of indirect effects on non‐targeted N. alba pads or flowers. When foraging in the aquatic environment, beavers are highly selective and can have a minor effect on food resources whilst feeding optimally and opportunistically. Since beavers demonstrate adaptive foraging strategies depending on their foraging environment, this knowledge should be incorporated into future decisions on further reintroduction or habitat restoration programmes.

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“…(2) Aquatic plants were consumed by mastodons (Lepper et al, 1991;Teale and Miller, 2012 Severud et al (2013) found that "floating leaf" aquatic macrophyte vegetation in northern Minnesota has δ 13 C values on average about 4‰ higher than woody terrestrial vegetation, and Milligan (2008) found that freshwater vegetation in both Old Crow (Yukon Territory) and James Bay (Quebec) had significantly higher δ 13 C values than terrestrial vegetation, by about 2-10‰. On theoretical grounds, Saunders et al (2010) suggested that submerged aquatic plants available to the Brewster Creek mastodon (Illinois) would have had higher δ 13 C values than terrestrial plants because of dissolved limestone in local water bodies.…”

Section: General and Seasonal Environmental Changes Over Timementioning

confidence: 99%

Environmental change and seasonal behavior of mastodons in the Great Lakes region inferred from stable isotope analysis

Metcalfe¹,

Longstaffe²

2014

Quat. res.

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We investigate seasonal variations in the diet and drinking water of four Great Lakes mastodon (Mammut americanum) specimens using stable isotope analysis of serially sampled inner-enamel bioapatite structural carbonate (δ 13 C sc , δ 18 O sc ), and previously published bulk analyses. Isotopic analyses and thin section measurements showed that mastodon tooth enamel extension rates (~12-4 mm/yr, decreasing toward the cervix) were lower than those of mammoths or modern elephants. Mastodons had distinct and highly regular seasonal variations in δ 13 C sc and δ 18 O sc , which we interpret in the context of local glacial history and vegetation changes. Seasonal variations in δ 18 O were large but variations in δ 13 C were small, and may have been obscured if coarser sampling methods than our inner-enamel sampling approach were used. Thus, our approach may be particularly useful for understanding relatively small seasonal changes in δ 13 C within C 3 environments. The seasonal patterns, though not entirely conclusive, suggest that the Ontario mastodons did not migrate over very long distances. Rather, the climate and seasonal dietary patterns of mastodons within the region changed over time, from 12,400 to 10,400 14 C yr BP (~15,000 -12,000 cal yr BP). Insights gained using these methods can contribute to a better understanding of megafaunal extinctions and Paleoamerican lifeways.

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The role of forage availability on diet choice and body condition in American beavers (Castor canadensis)

Cited by 22 publications

References 66 publications

The forgotten prey of an iconic predator: a review of interactions between grey wolvesCanis lupusand beaversCastorspp.

The forgotten prey of an iconic predator: a review of interactions between grey wolvesCanis lupusand beaversCastorspp.

Beavers and lilies: selective herbivory and adaptive foraging behaviour

Environmental change and seasonal behavior of mastodons in the Great Lakes region inferred from stable isotope analysis

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