Lynx Population Dynamics in an Untrapped Refugium

Slough, Brian G.; Mowat, Garth

doi:10.2307/3802397

Cited by 100 publications

(137 citation statements)

References 35 publications

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“…For lynx, yearling females differed from adult females in their reproductive parameters (Slough and Mowat 1996). We therefore calculated reproduction for each group separately, with A and Y representing the proportion of females in each age class and subscripts denoting age-specific parameters.…”

Section: Production Per Biomass (P/b)mentioning

confidence: 99%

“…We know a priori that there are dramatic changes in standing biomass because of the pronounced cyclicity. Furthermore, research on this food web has demonstrated cyclic changes in productivity (reproduction and growth) and consumption (numeric and functional responses of predators) (Keith 1990; O'Donoghue and Krebs 1992; Krebs and others 1995;Rohner 1996;Slough and Mowat 1996;O'Donoghue andothers 1997, 1998b;Stefan 1998;Karels and others 2000). Appropriate parameterization of Ecopath models for the boreal forest food web may therefore require considerably more complex models than are acceptable for systems that are closer to equilibrium.…”

Section: Introductionmentioning

confidence: 99%

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Mass-Balance Analyses of Boreal Forest Population Cycles: Merging Demographic and Ecosystem Approaches

Ruesink

Hodges

2002

Ecosystems

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Using Ecopath, a trophic mass-balance modeling framework, we developed six models of a Canadian boreal forest food web centered around snowshoe hares, which have conspicuous 10-year population cycles. Detailed models of four phases of the cycle were parameterized with long-term population data for 12 vertebrate taxa. We also developed five other models that, instead of observed data, used parameter values derived from standard assumptions. Specifically, in the basic model, production was assumed to equal adult mortality, feeding rates were assumed to be allometric, and biomass was assumed to be constant. In the actual production, functional response, and biomass change models, each of these assumed values from the basic model was replaced individually by field data. Finally, constant biomass models included actual production by all species and functional responses of mammalian predators and revealed the proportion of herbivore production used by species at higher trophic levels. By comparing these models, we show that detailed information on densities and demographics was crucial to constructing models that captured dynamic aspects of the food web. These detailed models reinforced an emerging picture of the causes and consequences of the snowshoe hare cycle. The snowshoe hare decline and low phases were coincident with times when per capita production was relatively low and predation pressure high. At these times, ecotrophic efficiencies (EE) suggest there was little production that remained unconsumed by predators. The importance of both production and consumption implies that bottom-up and top-down factors interacted to cause the cycle. EEs of other herbivores (ground squirrels, red squirrels, small mammals, small birds, grouse) were generally low, suggesting weak top-down effects. Predation rates on these "alternative" prey, except ground squirrels, were highest when predators were abundant, not when hares were rare; consequently, any topdown effects reflected predator biomass and were not a function of diet composition or functional responses. Finally, several predators (lynx, coyotes, great-horned owls) showed clear bottom-up regulation, reproducing only when prey exceeded threshold densities. Taken altogether, these results demonstrate that ecosystem models parameterized by population data can describe the dynamics of nonequilibrial systems, but only when detailed information is available for the species modeled.

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Section: Production Per Biomass (P/b)mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Mass-Balance Analyses of Boreal Forest Population Cycles: Merging Demographic and Ecosystem Approaches

Ruesink

Hodges

2002

Ecosystems

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“…The size of this sample unit was slightly smaller than a typical female home range and was employed to reduce the chance of missing individuals, but was still efficient for searching large landscapes . Female lynx typically have smaller home ranges than males (Koehler 1990;Poole 1994;Slough and Mowat 1996). Establishing a grid of survey units covering the study areas ensured that our search effort was spatially well distributed across available habitats .…”

Section: Snow-track Protocolmentioning

confidence: 99%

“…sensitivity to changes in use patterns, especially for species like lynx that are highly mobile and have large home ranges (Ward and Krebs 1985;Poole 1994;Slough and Mowat 1996;Aubry et al 2000). Changes in lynx occupancy can be quickly detected across extensive areas using snow-track surveys.…”

Section: Bmentioning

confidence: 99%

A Snow-tracking Protocol Used to Delineate Local Lynx, <em>Lynx canadensis</em>, Distributions

2004

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Determining Canada Lynx (Lynx canadensis) distribution is an important management need, especially at the southern extent of the species range where it is listed as threatened under the U. S. Endangered Species Act. We describe a systematic snowtrack based sampling framework that provides reliable distribution data for Canada Lynx. We used computer simulations to evaluate protocol efficacy. Based on these simulations, the probability of detecting lynx tracks during a single visit (8 km transect) to a survey unit ranged from approximately 0.23 for surveys conducted only one day after snowfall, to 0.78 for surveys conducted 7 days after a snowfall. If the survey effort was increased to three visits, then detection probabilities increased substantially from 0.58 for one day after snowfall to about 0.95 for surveys conducted 7 days after a snowfall. We tested the protocol in the Garnet Range, Montana, where most lynx were radio-collared. We documented a total of 189 lynx tracks during two winters (2001-2003). Lynx distribution based on snow-track surveys was coincident with the area defined through radio telemetry. Additionally, we conducted snow-track surveys in areas of western Wyoming where lynx were believed present but scarce. We detected a total of six lynx tracks during three winters (1999-2002). In Wyoming , where lynx presence was inferred from a few tracks, we verified species identification by securing genetic samples (hairs from daybeds) along track-lines.

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“…Slough and Mowat, 1996;Penteriani et al, 2002). Because of their low densities, these species can easily be eradicated from an area when they are hunted (Breitenmoser, 1998).…”

Section: 3mentioning

confidence: 99%