Spatially varying density dependence drives a shifting mosaic of survival in a recovering apex predator (<i>Canis lupus</i>)

O’Neil, Shawn T.; Bump, Joseph K.; Beyer, Dean E.

doi:10.1002/ece3.3463

Cited by 21 publications

(21 citation statements)

References 87 publications

(137 reference statements)

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“…In contrast, IPD or IDD should lead to differences in average fitness between habitat classes. Although we could not analyse metrics of fitness such as reproductive success in this study, analyses of adult survival within the same population indicated that survival varied spatially and was reduced in agricultural areas (O'Neil et al, 2017; Stenglein, Gilbert, et al, 2015). In addition, there were several observations of intraspecific killing in this population and adjacent populations (O'Neil, 2017; Stenglein et al, 2015), suggesting territorial interference.…”

Section: Discussionmentioning

confidence: 84%

“…This scenario is most likely to arise when two major elements of habitat selection are prey abundance and the risk of human‐caused mortality, a common circumstance for populations of large carnivores. In such cases, density‐dependent mortality due to humans (Murray et al, 2010) and other factors would create an uneven landscape mosaic of fitness (O'Neil, Bump, & Beyer, 2017; Smith et al, 2010; Stenglein, Gilbert, Wydeven, & Deelen, 2015). If individuals respond to spatially varying mortality risk according to the IPD, the prediction would be that high‐risk sites are selected only after low‐risk sites have become occupied.…”

Section: Discussionmentioning

confidence: 99%

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Territoriality drives preemptive habitat selection in recovering wolves: Implications for carnivore conservation

O’Neil

Vucetich

Beyer

et al. 2020

Journal of Animal Ecology

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1. According to the ideal-free distribution (IFD), individuals within a population are free to select habitats that maximize their chances of success. Assuming knowledge of habitat quality, the IFD predicts that average fitness will be approximately equal among individuals and between habitats, while density varies, implying that habitat selection will be density dependent. Populations are often assumed to follow an IFD, although this assumption is rarely tested with empirical data, and may be incorrect when territoriality indicates habitat selection tactics that deviate from the IFD (e.g. ideal-despotic distribution or ideal-preemptive distribution).2. When territoriality influences habitat selection, species' density will not directly reflect components of fitness such as reproductive success or survival. In such cases, assuming an IFD can lead to false conclusions about habitat quality. We tested theoretical models of density-dependent habitat selection on a species known to exhibit territorial behaviour in order to determine whether commonly applied habitat models are appropriate under these circumstances.3. We combined long-term radiotelemetry and census data from grey wolves Canis lupus in the Upper Peninsula of Michigan, USA to relate spatiotemporal variability in wolf density to underlying classifications of habitat within a hierarchical state-space modelling framework. We then iteratively applied isodar analysis to evaluate which distribution of habitat selection best described this recolonizing wolf population. 4. The wolf population in our study expanded by >1,000% during our study (~50 to >600 individuals), and density-dependent habitat selection was most consistent with the ideal-preemptive distribution, as opposed to the ideal-free or idealdespotic alternatives. Population density of terrestrial carnivores may not be positively correlated withthe fitness value of their habitats, and density-dependent habitat selection patterns may help to explain complex predator-prey dynamics and cascading indirect effects. Source-sink population dynamics appear likely when species exhibit rapid growth and occupy interspersed habitats of contrasting quality. These conditions are likely and have implications for large carnivores in many systems, such as areas in North America and Europe where large predator species are currently recolonizing their former ranges.

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Section: Discussionmentioning

confidence: 84%

Section: Discussionmentioning

confidence: 99%

Territoriality drives preemptive habitat selection in recovering wolves: Implications for carnivore conservation

O’Neil

Vucetich

Beyer

et al. 2020

Journal of Animal Ecology

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“…The same is true at high density, but, crucially, when territories nearly saturate the landscape, closure assumption violations are less consequential, and tend to offset each other for adjacent sample units. In both Wisconsin and elsewhere, it is likely that wolf home ranges are aggregated in the highest quality habitat where mortality risk is lowest, to the extent that these areas are nearly saturated (Mladenoff 2009, O'Neil et al 2017). Montana uses a large (600 km 2 ) sampling grid resolution, multiple state‐wide observation data sources, and informative landscape covariates to predict occupancy of wolves and scale up to abundance (Rich et al 2013, Montana Fish, Wildlife, and Parks 2018), and most occupied sample units are aggregated in the western part of the state (Rich et al 2013: figure 1).…”

Section: Discussionmentioning

confidence: 99%

Scaling Occupancy Estimates up to Abundance for Wolves

et al. 2021

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Management of wildlife populations often requires reliable estimates of population size or distribution. Estimating abundance can be logistically difficult, and occupancy models have been used as a less expensive proxy for abundance estimation. Another alternative is to use independent estimates of home‐range size and mean group size to directly scale occupancy estimates up to abundance. We used simulations to explore when scaling occupancy up to abundance is reliable, and as an example we applied an occupancy approach to estimate abundance of wolves (Canis lupus) from roadside snow‐tracking surveys in northern Wisconsin, USA, in 2016 and 2018. Estimates of wolf abundance were plausible and compared favorably with independent estimates produced by territory mapping, and snow‐tracking data requirements were lower than for territory mapping. Simulation results suggested that reasonable abundance estimates could be obtained under some conditions but also that severe positive bias could result under other conditions, especially when populations were small and dispersed, home range size was small, and areal sampling units were large. Positive bias in abundance estimates occurs because of closure assumption violations when tracks from a single wolf or pack are detected in >1 sample unit, and the sum of the sample unit areas where tracks were detected exceed the sum of the home range areas. Bias was minimized when sampling units were small relative to home range size or when sampling units were route segments that approximate point sample units, and when home ranges were highly aggregated. We conclude that, although caution is warranted when scaling occupancy estimates up to abundance, scaled occupancy models can provide feasible and reliable estimates of abundance, assuming home range size and mean group size are accurately known or estimated, sampling units are appropriately chosen, and covariates that aggregate home ranges can be used to accurately predict occupancy probability. © 2021 The Authors. The Journal of Wildlife Management published by Wiley Periodicals LLC on behalf of The Wildlife Society.

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“…In 2007, the state adopted a geographically stratified sampling plan to reduce the cost and effort of the survey. A panel design was implemented to increase the precision of abundance estimates which ensured that some sampled units were counted during successive years [48,50].…”

Section: Methodsmentioning

confidence: 99%

Territorial landscapes: incorporating density-dependence into wolf habitat selection studies

2019

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Habitat selection is a process that spans space, time and individual life histories. Ecological analyses of animal distributions and preferences are most accurate when they account for inherent dynamics of the habitat selection process. Strong territoriality can constrain perception of habitat availability by individual animals or groups attempting to colonize or establish new territory. Because habitat selection is a function of habitat availability, broad-scale changes in habitat availability or occupancy can drive density-dependent habitat functional responses. We investigated density-dependent habitat selection over a 19-year period of grey wolf (Canis lupus) recovery in Michigan, USA, using a generalized linear mixed model framework to develop a resource selection probability function (RSPF) with habitat coefficients conditioned on random effects for wolf packs and random year intercepts. In addition, we allowed habitat coefficients to vary as interactions with increasing wolf density over space and time. Results indicated that pack presence was driven by factors representing topography, human development, winter prey availability, forest structure, roads, streams and snow. Importantly, responses to many of these predictors were density-dependent. Spatio-temporal dynamics and population changes can cause considerable variation in wildlife–habitat relationships, possibly confounding interpretation of conventional habitat selection models. By incorporating territoriality into an RSPF analysis, we determined that wolves' habitat use in Michigan shifted over time, for example, exhibiting declining responses to winter prey indices and switching from positive to negative responses with respect to stream densities. We consider this an important example of a habitat functional response in wolves, driven by colonization, density-dependence and changes in occupancy during a time period of range expansion and population increase.

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Spatially varying density dependence drives a shifting mosaic of survival in a recovering apex predator (Canis lupus)

Cited by 21 publications

References 87 publications

Territoriality drives preemptive habitat selection in recovering wolves: Implications for carnivore conservation

Territoriality drives preemptive habitat selection in recovering wolves: Implications for carnivore conservation

Scaling Occupancy Estimates up to Abundance for Wolves

Territorial landscapes: incorporating density-dependence into wolf habitat selection studies

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