Predation Risk Affects Reproductive Physiology and Demography of Elk

Creel, Scott; Christianson, David; Liley, Stewart; Winnie, John A.

doi:10.1126/science.1135918

Cited by 537 publications

(427 citation statements)

References 8 publications

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“…Many of these adjustments can come at a cost to individual and population fitness because of a decrease in foraging time and/or because prey species are forced to forage in habitats with suboptimal forage availability, potentially reducing reproductive rates and affecting prey demography (Creel et al. 2007). Although smaller‐scale experimental studies have demonstrated strong and widespread effects of predation risk (e.g., Preisser et al.…”

Section: Introductionmentioning

confidence: 99%

Limited spatial response to direct predation risk by African herbivores following predator reintroduction

Davies

Tambling

Kerley

et al. 2016

Ecology and Evolution

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Predators affect ecosystems not only through direct mortality of prey, but also through risk effects on prey behavior, which can exert strong influences on ecosystem function and prey fitness. However, how functionally different prey species respond to predation risk and how prey strategies vary across ecosystems and in response to predator reintroduction are poorly understood. We investigated the spatial distributions of six African herbivores varying in foraging strategy and body size in response to environmental factors and direct predation risk by recently reintroduced lions in the thicket biome of the Addo Elephant National Park, South Africa, using camera trap surveys, GPS telemetry, kill site locations and Light Detection and Ranging. Spatial distributions of all species, apart from buffalo, were driven primarily by environmental factors, with limited responses to direct predation risk. Responses to predation risk were instead indirect, with species distributions driven by environmental factors, and diel patterns being particularly pronounced. Grazers were more responsive to the measured variables than browsers, with more observations in open areas. Terrain ruggedness was a stronger predictor of browser distributions than was vegetation density. Buffalo was the only species to respond to predator encounter risk, avoiding areas with higher lion utilization. Buffalo therefore behaved in similar ways to when lions were absent from the study area. Our results suggest that direct predation risk effects are relatively weak when predator densities are low and the time since reintroduction is short and emphasize the need for robust, long‐term monitoring of predator reintroductions to place such events in the broader context of predation risk effects.

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Section: Introductionmentioning

confidence: 99%

Limited spatial response to direct predation risk by African herbivores following predator reintroduction

Davies

Tambling

Kerley

et al. 2016

Ecology and Evolution

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“…2001; Creel et al. 2007) with population effects potentially exceeding those of direct predation (Creel and Christianson 2008). It has been suggested that prey species may lose their antipredator behavior over time if predators disappear from the system (Sih et al.…”

Section: Introductionmentioning

confidence: 99%

Phantoms of the forest: legacy risk effects of a regionally extinct large carnivore

Sahlén

Noell

DePerno

et al. 2016

Ecology and Evolution

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The increased abundance of large carnivores in Europe is a conservation success, but the impact on the behavior and population dynamics of prey species is generally unknown. In Europe, the recolonization of large carnivores often occurs in areas where humans have greatly modified the landscape through forestry or agriculture. Currently, we poorly understand the effects of recolonizing large carnivores on extant prey species in anthropogenic landscapes. Here, we investigated if ungulate prey species showed innate responses to the scent of a regionally exterminated but native large carnivore, and whether the responses were affected by human‐induced habitat openness. We experimentally introduced brown bear Ursus arctos scent to artificial feeding sites and used camera traps to document the responses of three sympatric ungulate species. In addition to controls without scent, reindeer scent Rangifer tarandus was used as a noncarnivore, novel control scent. Fallow deer Dama dama strongly avoided areas with bear scent. In the presence of bear scent, all ungulate species generally used open sites more than closed sites, whereas the opposite was observed at sites with reindeer scent or without scent. The opening of forest habitat by human practices, such as forestry and agriculture, creates a larger gradient in habitat openness than available in relatively unaffected closed forest systems, which may create opportunities for prey to alter their habitat selection and reduce predation risk in human‐modified systems that do not exist in more natural forest systems. Increased knowledge about antipredator responses in areas subjected to anthropogenic change is important because these responses may affect prey population dynamics, lower trophic levels, and attitudes toward large carnivores. These aspects may be of particular relevance in the light of the increasing wildlife populations across much of Europe.

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“…Understanding these consequences is important because they can enhance or obscure consumptive effects on prey population growth, life history, and resource use . Creel et al (2007) suggested that pregnancy rates of elk (Cervus elaphus) in the greater Yellowstone ecosystem, as determined indirectly through measurement of average fecal progesterone levels, decreased in the presence of wolves (Canis lupus). This apparent effect was attributed to changes in foraging patterns of elk that carried nutritional costs rather than changes in glucocorticoid concentrations due to stress (Creel et al 2009, Christianson andCreel 2010).…”

Section: Introductionmentioning

confidence: 99%

“…Likewise, the probability that elk are pregnant in mid-to late winter follows a logistic curve as a function of body fat (Cook et al 2004b). Thus, the hypothesized mechanism for lower pregnancy rates in elk as a consequence of antipredator responses that carry nutritional costs is that reduced body condition (fat, protein) results in (1) elk not conceiving due to low body fat during the autumn breeding season, (2) elk conceiv- ing but losing the fetus due to inadequate winter nutrition and inadequate progesterone levels to maintain pregnancy, or (3) some combination of both (Creel et al 2007(Creel et al , 2009). To prevent elk from accruing enough body fat to get pregnant, elk antipredator behavioral responses to wolves would have to result in limited forage intake or force elk into areas of lower forage quality during spring and summer.…”

Section: Introductionmentioning

confidence: 99%

Body condition and pregnancy in northern Yellowstone elk: Evidence for predation risk effects?

White

Garrott

Hamlin

et al. 2011

Ecological Applications

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Abstract. S. Creel et al. reported a negative correlation between fecal progesterone concentrations and elk : wolf ratios in greater Yellowstone elk (Cervus elaphus) herds and interpreted this correlation as evidence that pregnancy rates of elk decreased substantially in the presence of wolves (Canis lupus). Apparently, the hypothesized mechanism is that decreased forage intake reduces body condition and either results in elk failing to conceive during the autumn rut or elk losing the fetus during winter. We tested this hypothesis by comparing age-specific body condition (percentage ingesta-free body fat) and pregnancy rates for northern Yellowstone elk, one of the herds sampled by Creel et al., before (1962Creel et al., before ( -1968 and after (2000)(2001)(2002)(2003)(2004)(2005)(2006) wolf restoration using indices developed and calibrated for Rocky Mountain elk. Mean age-adjusted percentage body fat of female elk was similarly high in both periods (9.0% 6 0.9% pre-wolf; 8.9% 6 0.8% post-wolf). Estimated pregnancy rates (proportion of females that were pregnant) were 0.91 pre-wolf and 0.87 post-wolf for 4-9 year-old elk (95% CI on difference ¼ À0.15 to 0.03, P ¼ 0.46) and 0.64 pre-wolf and 0.78 post-wolf for elk .9 years old (95% CI on difference ¼ À0.01 to 0.27, P ¼ 0.06). Thus, there was little evidence in these data to support strong effects of wolf presence on elk pregnancy. We caution that multiple lines of evidence and/or strong validation should be brought to bear before relying on indirect measures of how predators affect pregnancy rates.

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Predation Risk Affects Reproductive Physiology and Demography of Elk

Cited by 537 publications

References 8 publications

Limited spatial response to direct predation risk by African herbivores following predator reintroduction

Limited spatial response to direct predation risk by African herbivores following predator reintroduction

Phantoms of the forest: legacy risk effects of a regionally extinct large carnivore

Body condition and pregnancy in northern Yellowstone elk: Evidence for predation risk effects?

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