Habitat selection by Dall's sheep (<i>Ovis dalli</i>): maternal trade‐offs

Rachlow, Janet L.; Bowyer, R. Terry

doi:10.1111/j.1469-7998.1998.tb00120.x

Cited by 124 publications

(106 citation statements)

References 36 publications

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“…In fact, as suggested by the concept of hierarchical selection (Johnson 1980), the same animal species may even select certain habitat features on one spatial scale and avoid them on another scale (Rachlow & Bowyer 1998, reviewed in Bowyer & Kie 2006. Thus, for a better understanding of the habitat requirements of a species it may be necessary to sample on different scales (Bowyer & Kie 2006).…”

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confidence: 99%

Foraging sites of Eurasian lynxLynx lynx: relative importance of microhabitat and prey occurrence

Belotti

Červený

Šustr³

et al. 2013

Wildlife Biology

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The choice of foraging areas by large carnivores can be driven both by prey abundance and landscape attributes and it is likely that the relative importance of these two components changes on different spatial scales. In the Bohemian Forest (southwestern Bohemia, Czech Republic), we focused on the effect of microhabitat. We tested if Eurasian lynx Lynx lynx hunted merely in areas where its main prey, roe deer Capreolus capreolus and red deer Cervus elaphus, occurred ('preyoccurrence hypothesis') or if there were fine-scale habitat features that increased prey catchability ('landscape hypothesis'). Fine-scale habitat features were recorded at sites where an ungulate had been killed and located using telemetry or by chance (in winter: N ¼ 29 roe deer, N ¼ 18 red deer; in summer: N ¼ 33 roe deer, N ¼ 5 red deer). We compared these features with those recorded at locations where live red or roe deer were recorded using telemetry (N¼ 100 per species per six-month period). In winter, lynx killed both roe and red deer at sites where there was a greater heterogeneity in terms of visibility than at sites where live ungulates were recorded, i.e. at kill sites there were both good stalking cover and good visibility. In addition, the risk of predation for red deer was negatively correlated with tree density. In summer, the risk of predation for roe deer was not associated with any of the habitat variables measured. Thus, the presence of a kill was associated with particular fine-scale habitat features in winter, while in summer it was simply associated with where prey occurred. A deeper understanding of the type of habitat favoured by lynx is fundamental to the management and conservation of this species. Based on our results, forest management should ensure that the level of habitat heterogeneity is favourable for lynx.

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confidence: 99%

Foraging sites of Eurasian lynxLynx lynx: relative importance of microhabitat and prey occurrence

Belotti

Červený

Šustr³

et al. 2013

Wildlife Biology

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“…Second, foraging distance away from escape terrain may be greater due to a low snowline elevation, leading to greater risk of predation and less efficient foraging. For example, ewes foraged closer to escape terrain during a mild spring when forage was plentiful relative to a late spring when forage availability and quality was lower and ewes foraged less efficiently [11].…”

Section: Discussionmentioning

confidence: 99%

“…Range-wide, Dall sheep populations have declined by 21% since 1990 [8] but the causes remain unknown [9]. Harsh spring weather was shown to reduce horn growth rates in the Yukon [10] and pregnant Dall sheep in Denali National Park were found to avoid snow-covered areas [11]. However, no studies have examined impacts of spring snow conditions on Dall sheep populations across their range, in part due to a lack of available regional snow products that capture important features of snow-covered landscapes, such as the elevation of spring snowline.…”

Section: Introductionmentioning

confidence: 99%

Remote Sensing of 2000–2016 Alpine Spring Snowline Elevation in Dall Sheep Mountain Ranges of Alaska and Western Canada

et al. 2017

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Abstract:The lowest elevation of spring snow ("snowline") is an important factor influencing recruitment and survival of wildlife in alpine areas. In this study, we assessed the spatial and temporal variability of alpine spring snowline across major Dall sheep mountain areas in Alaska and northwestern Canada. We used a daily MODIS snow fraction product to estimate the last day of 2000-2016 spring snow for each 500-m pixel within 28 mountain areas. We then developed annual (2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010)(2011)(2012)(2013)(2014)(2015)(2016) regression models predicting the elevation of alpine snowline during mid-May for each mountain area. MODIS-based regression estimates were compared with estimates derived using a Normalized Difference Snow Index from Landsat-8 Operational Land Imager (OLI) surface reflectance data. We also used 2000-2009 decadal climate grids to estimate total winter precipitation and mean May temperature for each of the 28 mountain areas. Based on our MODIS regression models, the 2000-2016 mean 15 May snowline elevation ranged from 339 m in the cold arctic class to 1145 m in the interior mountain class. Spring snowline estimates from MODIS and Landsat OLI were similar, with a mean absolute error of 106 m. Spring snowline elevation was significantly related to mean May temperature and total winter precipitation. The late spring of 2013 may have impacted some sheep populations, especially in the cold arctic mountain areas which were snow-covered in mid-May, while some interior mountain areas had mid-May snowlines exceeding 1000 m elevation. We found this regional (>500,000 km 2 ) remote sensing application useful for determining the inter-annual and regional variability of spring alpine snowline among 28 mountain areas.

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“…Although tradeoffs between foraging and predation risk are well documented (e.g., Sih 1980, Lima 1985, Houston et al 1993, Rachlow and Bowyer 1998, Grand 2002, tradeoffs between the functional properties of cover in relation to predation risk are not well understood. A first step to understanding if and how animals make tradeoffs between concealment and visibility is to quantify the relationship between these properties across habitats and scales of measurement.…”

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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Habitat selection by Dall's sheep (Ovis dalli): maternal trade‐offs

Cited by 124 publications

References 36 publications

Foraging sites of Eurasian lynxLynx lynx: relative importance of microhabitat and prey occurrence

Foraging sites of Eurasian lynxLynx lynx: relative importance of microhabitat and prey occurrence

Remote Sensing of 2000–2016 Alpine Spring Snowline Elevation in Dall Sheep Mountain Ranges of Alaska and Western Canada

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

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