Regional differences in winter diets of bobcats in their northern range

Newbury, Roberta K.; Hodges, Karen E.

doi:10.1002/ece3.4576

Cited by 17 publications

(14 citation statements)

References 44 publications

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“…Most studies documented range expansion (n = 13), instead of contraction (n = 4) or stability (n = 1). (Litvaitis & Harrison, 1989;Major & Sherburne, 1987;Newbury & Hodges, 2018). A similar pattern has been inferred for other purportedly snow-limited carnivores, including fisher Pekania pennanti (Jensen & Humphries, 2019;McLellan, Vashon, Johnson, Crowley, & Vashon, 2018) and coyotes Canis latrans (Litvaitis & Harrison, 1989;Patterson, Benjamin, & Messier, 1998).…”

Section: Ta B L Esupporting

confidence: 73%

“…The availability of habitat or prey often ameliorated the effect of negative abiotic factors. For instance, bobcats Lynx rufus , normally snow limited, can persist for years in deep snow locales along high‐latitude limits if there are large or abundant prey (Litvaitis & Harrison, ; Major & Sherburne, ; Newbury & Hodges, ). A similar pattern has been inferred for other purportedly snow‐limited carnivores, including fisher Pekania pennanti (Jensen & Humphries, ; McLellan, Vashon, Johnson, Crowley, & Vashon, ) and coyotes Canis latrans (Litvaitis & Harrison, ; Patterson, Benjamin, & Messier, ).…”

Section: Review Of Evidence For Irltmentioning

confidence: 99%

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Interactive range‐limit theory (iRLT): An extension for predicting range shifts

Sirén

Morelli

2019

Journal of Animal Ecology

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A central theme of range‐limit theory (RLT) posits that abiotic factors form high‐latitude/altitude limits, whereas biotic interactions create lower limits. This hypothesis, often credited to Charles Darwin, is a pattern widely assumed to occur in nature. However, abiotic factors can impose constraints on both limits and there is scant evidence to support the latter prediction. Deviations from these predictions may arise from correlations between abiotic factors and biotic interactions, as a lack of data to evaluate the hypothesis, or be an artifact of scale. Combining two tenets of ecology—niche theory and predator–prey theory—provides an opportunity to understand how biotic interactions influence range limits and how this varies by trophic level. We propose an expansion of RLT, interactive RLT (iRLT), to understand the causes of range limits and predict range shifts. Incorporating the main predictions of Darwin's hypothesis, iRLT hypothesizes that abiotic and biotic factors can interact to impact both limits of a species’ range. We summarize current thinking on range limits and perform an integrative review to evaluate support for iRLT and trophic differences along range margins, surveying the mammal community along the boreal‐temperate and forest‐tundra ecotones of North America. Our review suggests that range‐limit dynamics are more nuanced and interactive than classically predicted by RLT. Many (57 of 70) studies indicate that biotic factors can ameliorate harsh climatic conditions along high‐latitude/altitude limits. Conversely, abiotic factors can also mediate biotic interactions along low‐latitude/altitude limits (44 of 68 studies). Both scenarios facilitate range expansion, contraction or stability depending on the strength and the direction of the abiotic or biotic factors. As predicted, biotic interactions most often occurred along lower limits, yet there were trophic differences. Carnivores were only limited by competitive interactions (n = 25), whereas herbivores were more influenced by predation and parasitism (77%; 55 of 71 studies). We highlight how these differences may create divergent range patterns along lower limits. We conclude by (a) summarizing iRLT; (b) contrasting how our model system and others fit this hypothesis and (c) suggesting future directions for evaluating iRLT.

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Section: Ta B L Esupporting

confidence: 73%

Section: Review Of Evidence For Irltmentioning

confidence: 99%

Interactive range‐limit theory (iRLT): An extension for predicting range shifts

Sirén

Morelli

2019

Journal of Animal Ecology

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“…However, the availability of primary prey species, which were generally higher in low biomass forests, countered the negative effect of snow for these carnivores, indicating the importance of food in areas with adverse climate. Indeed, the reliance on a diversity of prey, and larger prey species in particular, is important for northern bobcat and coyote populations during winter (Litvaitis et al, 1986; Litvaitis & Harrison, 1989; Newbury & Hodges, 2018). Similar results have been found for fishers living in deep snow regions (Jensen & Humphries, 2019; McLellan et al, 2018), supporting our findings.…”

Section: Discussionmentioning

confidence: 99%

“…However, we found bobcats to have the greatest potential impact on lynx occupancy through the indirect effect of snow and associations with similar prey. Bobcats and lynx are phylogenetically similar (Koen et al, 2014) and can have similar diets (Ivan & Shenk, 2016; Litvaitis et al, 1986; Newbury & Hodges, 2018); thus, competition between these species should be fierce and result in exclusion at broad spatial scales (Godsoe et al, 2017). Indeed, these species rarely co‐occurred during our study, whereas coyotes and fishers overlapped considerably with lynx.…”

Section: Discussionmentioning

confidence: 99%

Abiotic stress and biotic factors mediate range dynamics on opposing edges

Sirén

Sutherland

Bernier

et al. 2021

Journal of Biogeography

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Aim In the face of global change, understanding causes of range limits are one of the most pressing needs in biogeography and ecology. A prevailing hypothesis is that abiotic stress forms cold (upper latitude/altitude) limits, whereas biotic interactions create warm (lower) limits. A new framework – Interactive Range‐Limit Theory (iRLT) – asserts that positive biotic factors such as food availability can ameliorate abiotic stress along cold edges, whereas abiotic stress can have a positive effect and mediate biotic interactions (e.g., competition) along warm limits. Location Northeastern United States Taxon Carnivora Methods We evaluated two hypotheses of iRLT using occupancy and structural equation modeling (SEM) frameworks based on data collected over a 6‐year period (2014–2019) of six carnivore species across a broad latitudinal (42.8–45.3°N) and altitudinal (3–1451 m) gradient. Results We found that snow directly limits populations, but prey or habitat availability can influence range dynamics along cold edges. For example, bobcats (Lynx rufus) and coyotes (Canis latrans) were limited by deep snow and long winters, but the availability of prey had a strong positive effect. Conversely, snow had a strong positive effect on the warm limits of Canada lynx (Lynx canadensis), countering the negative effect of competition with the phylogenetically similar bobcat and with coyotes, highlighting how climate mediates competition between species. Main conclusions We used an integrated dataset that included competitors and prey species collected at the same spatial and temporal scale. As such, this design, along with a causal modeling framework (SEM), allowed us to evaluate community‐wide hypotheses at macroecological scales and identify coarse‐scale drivers of species' range limits. Our study supports iRLT and underscores the need to consider direct and indirect mechanisms for studying range dynamics and species' responses to global change.

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“…Furthermore, bobcats in New England are at the northern edge of their range and living at the extremes of their environmental tolerance levels (Hansen 2007). The metabolic demands on bobcats during winters at northern latitudes are greater than in more southerly parts of their range (Newbury and Hodges 2019), resulting in dietary and physiological changes (Hamilton and Hunter 1939, Litvaitis et al 1986a, Newbury and Hodges 2018.…”

mentioning

confidence: 99%

Bobcat Hair Cortisol Correlates with Land Use and Climate

2021

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Bobcats (Lynx rufus) have been increasing in abundance in the northeast United States despite a corresponding trend of increased anthropogenic land uses. Inhabiting areas of high human land use can affect stress levels, and hence cortisol titers, for wildlife species by increasing frequency of human interaction and altering habitats. In turn, increased cortisol levels can have negative effects at the individual and population level including decreased immune function, slowed growth and tissue repair, reduced reproductive capacity, and nutritional deficiencies. We quantified cortisol in bobcats across New Hampshire and Vermont, USA, using hair samples, then explored associations between hair cortisol and various organismal, land use, land cover, and climatic variables at 2 different spatial scales. Hair cortisol differed by season and bobcat mass. On average, cortisol levels were higher in fall than in spring, and larger bobcats had lower cortisol levels. Anthropogenic land uses-especially residential and agricultural uses-were the most important predictors of hair cortisol at the town scale ( ̅x area = 93 km 2 ). At a larger scale (Wildlife Management Units; ̅x area = 1,256 km 2 ), temperature and precipitation were better predictors of hair cortisol, suggesting that extreme weather may have significant effects on bobcat population dynamics. Our results highlight the importance of landscape composition and local conditions in the sustainable management of furbearer populations.

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Regional differences in winter diets of bobcats in their northern range

Cited by 17 publications

References 44 publications

Interactive range‐limit theory (iRLT): An extension for predicting range shifts

Interactive range‐limit theory (iRLT): An extension for predicting range shifts

Abiotic stress and biotic factors mediate range dynamics on opposing edges

Bobcat Hair Cortisol Correlates with Land Use and Climate

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