Accounting for Individuals, Uncertainty, and Multiscale Clustering in Core Area Estimation

Wilson, Ryan R.; Hooten, Mevin B.; Strobel, Bradley N.; Shivik, John A.

doi:10.2193/2009-438

Cited by 13 publications

(12 citation statements)

References 30 publications

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“…Therefore, this study relied on indirect sampling methods to gain insight into the ranging patterns of this relatively unknown subspecies (Doran et al 2002;Rogers et al 2004;Sunderland-Groves et al 2009). Gorillas live in social groups and all weaned group members construct nests in close proximity to one another each night, forming 'nest sites' (Ganas et al 2008;Schaller 1963;Williamson 1988). During the day, groups move and feed between nest sites, leaving obvious trails of discarded food, feces, and trampled vegetation (Ganas et al 2008;Rogers et al 2004).…”

Section: Subpopulation Range Calculationmentioning

confidence: 99%

Subpopulation range estimation for conservation planning: a case study of the critically endangered Cross River gorilla

Sawyer

2012

Biodivers Conserv

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Measuring and characterizing the area utilized by a population or species is essential for assessment of conservation status and for effective allocation of habitat to ensure population persistence. Yet population-level range delineation is complicated by the variety of available techniques coupled with a lack of empirical methods to compare the relative value of these techniques. This study assesses the effect of model choice on resulting subpopulation range estimation for the critically endangered and patchily distributed Cross River gorilla, and evaluates the conservation conclusions that can be drawn from each model. Models considered range from basic traditional approaches (e.g. minimum convex polygon) to newer home range techniques such as local convex hull (LoCoH). Overlap analysis comparing sub-sampled to complete data sets are used to evaluate the robustness of various modeling techniques to data limitations. Likelihood cross validation criterion is employed to compare core range model performance. Results suggest that differing LoCoH models produce similar range estimates, are robust to data requirements, provide a good fit for core habitat estimation, and are best able to detect unused habitat within the subpopulation range. LoCoH methods may thus be useful for studies into habitat selection and factors limiting endangered species distributions. However, LoCoH models tend to over-fit data, and kernel methods may provide similar information about animal space use while supporting protection of larger swaths of critical habitat. Subpopulation range analyses for conservation/management planning should therefore explore multiple modeling techniques, and employ both qualitative and quantitative assessments to select the best models to inform decision making for species of conservation concern.

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Section: Subpopulation Range Calculationmentioning

confidence: 99%

Subpopulation range estimation for conservation planning: a case study of the critically endangered Cross River gorilla

Sawyer

2012

Biodivers Conserv

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“…For each home range, we also estimated a core area within the home range using an objective Bayesian analysis for evaluating the optimal isopleth(s) by categorizing the utilization distribution structure into ≥0 separate completely random point patterns (Wilson et al 2010). This method does not rely on an assumed 50% isopleth as a core area, but instead evaluates the underlying internal home range space-use patterns to delineate highly clustered or core areas.…”

Section: Data Analysesmentioning

confidence: 99%

Spatial Ecology of the Endangered Milne-Edwards’ Sifaka (Propithecus edwardsi): Do Logging and Season Affect Home Range and Daily Ranging Patterns?

et al. 2012

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Primates often live in human-altered habitats; Malagasy lemurs are no exception. It is important to understand if habitat alteration affects primates' space use patterns across multiple spatial and temporal scales, as this drives population density. We quantified the daily, seasonal, and annual space-use of seven groups of Milne-Edwards' sifaka (Propithecus edwardsi) living in unlogged and logged rain forest in Ranomafana National Park, Madagascar between December 2002 and November 2003. Concurrent data showed that sifakas consumed higher quality foods in the unlogged than in logged forests; thus we explored how space use patterns were related to energy use strategies. Sifaka groups in the logged rain forest traveled 7-13% less per day than groups in the unlogged rain forest, despite their larger home ranges (median: 46.12 and 23.52 ha, in the logged and unlogged forests, respectively). Sifakas may thus use an energy-minimizing strategy at the scale of the individual day but an energy-maximizing strategy at the annual home range scale. Sifakas exhibited fidelity to the home range across seasons, but their core area of use shifted considerably with season. We found no difference in population density between sites. However, given the Int J Primatol (2012) 33:305-321 interannual variability in sifaka foods, a multiyear study is needed to assess if energy strategies observed in this study are consistent across longer time periods. Our findings suggest that lemurs may persist in logged habitats by altering spatial use patterns; future work should attempt to quantify the threshold level of forest regeneration from logging that will allow lemurs to persist at similar densities as in unlogged forest.

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“…In this study, the home range was deWned as the area encompassed by the 95% isopleth. To estimate bobcat core areas, we analyzed home ranges for clusters of locations and used Bayesian methods to identify which isopleth partitioned the home range into homogeneous point patterns (Wilson et al 2010). This method is highly precise for characterizing points as occurring inside or outside the core area.…”

Section: Home Range Analysismentioning

confidence: 99%

Prey-mediated avoidance of an intraguild predator by its intraguild prey

et al. 2010

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Intraguild (IG) predation is an important factor influencing community structure, yet factors allowing coexistence of IG predator and IG prey are not well understood. The existence of spatial refuges for IG prey has recently been noted for their importance in allowing coexistence. However, reduction in basal prey availability might lead IG prey to leave spatial refuges for greater access to prey, leading to increased IG predation and fewer opportunities for coexistence. We determined how the availability of prey affected space-use patterns of bobcats (Lynx rufus, IG prey) in relation to coyote space-use patterns (Canis latrans, IG predators). We located animals from fall 2007 to spring 2009 and estimated bobcat home ranges and core areas seasonally. For each bobcat relocation, we determined intensity of coyote use, distance to water, small mammal biomass, and mean small mammal biomass of the home range during the season the location was collected. We built generalized linear mixed models and used Akaike Information Criteria to determine which factors best predicted bobcat space use. Coyote intensity was a primary determinant of bobcat core area location. In bobcat home ranges with abundant prey, core areas occurred where coyote use was low, but shifted to areas intensively used by coyotes when prey declined. High spatial variability in basal prey abundance allowed some bobcats to avoid coyotes while at the same time others were forced into more risky areas. Our results suggest that multiple behavioral strategies associated with spatial variation in basal prey abundance likely allow IG prey and IG predators to coexist.

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Accounting for Individuals, Uncertainty, and Multiscale Clustering in Core Area Estimation

Cited by 13 publications

References 30 publications

Subpopulation range estimation for conservation planning: a case study of the critically endangered Cross River gorilla

Subpopulation range estimation for conservation planning: a case study of the critically endangered Cross River gorilla

Spatial Ecology of the Endangered Milne-Edwards’ Sifaka (Propithecus edwardsi): Do Logging and Season Affect Home Range and Daily Ranging Patterns?

Prey-mediated avoidance of an intraguild predator by its intraguild prey

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