Survival and causes of mortality for pygmy rabbits (<i>Brachylagus idahoensis</i>) in Oregon and Nevada

Crawford, Justin A.; Anthony, Robert G.; Forbes, James T.; Lorton, Glenn A.

doi:10.1644/09-mamm-a-068.1

Cited by 30 publications

(32 citation statements)

References 64 publications

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“…Based on observed values of crude protein in browsed and unbrowsed plants plus the actual digestibility of protein, if pygmy rabbits only consumed unbrowsed plants at either site, they would need to eat nearly 3 g more of plant matter per day to meet protein requirements than if they ate browsed plants. By foraging more efficiently on plants with more protein (browsed plants), pygmy rabbits may spend less time exposed to predation, which can account for up to 88.9% of mortality (Crawford et al 2010). In addition, pygmy rabbits are constrained by high energy needs and strict energy budgets (Katzner et al 1997; Shipley et al 2006), and decreasing the number and duration of foraging bouts could play an important role in reducing energy expended on foraging and associated energetically expensive activities like evading predators while active (Camp et al 2012).…”

Section: Discussionmentioning

confidence: 99%

Plant protein and secondary metabolites influence diet selection in a mammalian specialist herbivore

et al. 2014

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For herbivores, nutrient intake is limited by the relatively low nutritional quality of plants and high concentrations of potentially toxic defensive compounds (plant secondary metabolites, PSMs) produced by many plants. In response to phytochemical challenges, some herbivores selectively forage on plants with higher nutrient and lower PSM concentrations relative to other plants. Pygmy rabbits (Brachylagus idahoensis) are dietary specialists that feed on sagebrush (Artemisia spp.) and forage on specific plants more than others within a foraging patch. We predicted that the plants with evidence of heavy foraging (browsed plants) would be of higher dietary quality than plants that were not browsed (unbrowsed). We used model selection to determine which phytochemical variables best explained the difference between browsed and unbrowsed plants. Higher crude protein increased the odds that plants would be browsed by pygmy rabbits and the opposite was the case for certain PSMs. Additionally, because pygmy rabbits can occupy foraging patches (burrows) for consecutive years, their browsing may influence the nutritional and PSM constituents of plants at the burrows. In a post hoc analysis, we did not find a significant relationship between phytochemical concentrations, browse status and burrow occupancy length. We concluded that pygmy rabbits use nutritional and chemical cues while making foraging decisions.

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Section: Discussionmentioning

confidence: 99%

Plant protein and secondary metabolites influence diet selection in a mammalian specialist herbivore

et al. 2014

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“…We then trapped pygmy rabbits in both areas as needed to maintain sample sizes through December 2011. We used both active and passive methods to trap rabbits (Green and Flinders , Crawford et al ). Active methods included flushing rabbits into their burrows and then placing a trap on that burrow or using a catch pole.…”

Section: Methodsmentioning

confidence: 99%

“…We followed standard model‐selection protocol and first made a list of a priori candidate models incorporating season, area, and individual covariate influences (Table ). Our list of a priori models included several models with hypothesized differences in survival in relation to 3 seasons defined as spring (Mar–Jun), summer and autumn (Jul–Oct), and winter (Nov–Feb; Sanchez and Rachlow , Crawford et al ). For other models, we extended winter to include March.…”

Section: Methodsmentioning

confidence: 99%

Space use, movements, and survival of pygmy rabbits in response to construction of a large pipeline

et al. 2018

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Little is known about how energy development affects pygmy rabbits (Brachylagus idahoensis). We quantified space use, movements, and survival of pygmy rabbits before and after construction of the Ruby Pipeline in Utah, USA, from 2010 to 2012. For 18 rabbits captured in and near the pipeline right‐of‐way (ROW) 1 month before construction, 95% kernel home ranges and 50% core areas were ≥3.7 times smaller 1 month after construction. Additionally, those 18 pygmy rabbits shifted the center of 50% core areas away from the ROW following construction (truex¯ = 34 m, SD = 36.3, range = −11 to 119 m). Also, 95% kernel home ranges and 50% core areas for 40 rabbits captured in and near the ROW and monitored for 18 months after construction were ≥2.6 times smaller than estimates of similar space use for 25 rabbits in a reference area during the same time. Only 3 of 22 rabbits captured in or near the ROW before construction began crossed the ROW during the 18 months following construction. Weekly estimates of survival for rabbits in or near the ROW were similar before, during, and after construction; and similar to survival rates for rabbits in a reference area. Our results will contribute to biologists’ understanding of the influence of habitat removal and fragmentation associated with the construction of linear features on pygmy rabbits and their habitat. © 2018 The Wildlife Society.

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“…Additionally, we examined how these properties and their relationship were manifested in habitat selection by pygmy rabbits (Brachylagus idahoensis), a sagebrush-dependent species that occupies areas in the Great Basin and the surrounding intermountain region of the western USA (Dobler and Dixon 1990). Because predation by both aerial and terrestrial predators is an important source of mortality for pygmy rabbits (Green and Flinders 1980, Estes-Zumpf and Rachlow 2009, Crawford et al 2010, Price et al 2010, and they rely, in part, on visual cues to detect predators, both concealment and visibility likely are important for this species. In this study, we isolated the predation response of pygmy rabbits from other behaviors such as foraging and resting by measuring habitat selection in the presence of disturbance.…”

Section: Introductionmentioning

confidence: 99%

Examining functional components of cover: the relationship between concealment and visibility in shrub‐steppe habitat

et al. 2013

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Abstract. The term ''cover'' has been used broadly in ecology, with a wide range of meanings, from thermal cover to security cover, to escape cover. Some habitat features could provide both thermal and security cover, or both concealment and escape cover; but in other cases, habitat features such as vegetation could impose a tradeoff between opposing functions of cover. Cover that conceals an animal from a predator also could reduce the animal's visibility and thus, its ability to detect a predator early enough to escape capture. We quantified the opposing functional properties of cover (concealment and visibility) and evaluated the relationship between these properties using continuous measures in sagebrush-steppe and grassland habitats. We hypothesized that concealment and visibility would be inversely related and that the slope of this relationship would differ among sites with varying density and patchiness of shrub vegetation, imposing differing tradeoff scenarios. Concealment and visibility were inversely, but not perfectly related, implying that animals must make tradeoffs between the properties of cover, but they could achieve higher levels of one property while giving up relatively less of the other. In addition, we examined potential tradeoffs by pygmy rabbits (Brachylagus idahoensis) by comparing concealment and visibility at locations used by rabbits with measurements collected at random locations. At a small scale, pygmy rabbits traded off visibility for concealment in dense and sparse vegetation, but not in patchy vegetation. Although cover is an intuitively simple concept, it is functionally more complex, and this study provides insight into the opposing mechanisms of cover that might influence habitat use. Our work provides an initial step towards more fully understanding how cover functionally relates to predation risk.

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Survival and causes of mortality for pygmy rabbits (Brachylagus idahoensis) in Oregon and Nevada

Cited by 30 publications

References 64 publications

Plant protein and secondary metabolites influence diet selection in a mammalian specialist herbivore

Plant protein and secondary metabolites influence diet selection in a mammalian specialist herbivore

Space use, movements, and survival of pygmy rabbits in response to construction of a large pipeline

Examining functional components of cover: the relationship between concealment and visibility in shrub‐steppe habitat

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