Winter feeding of elk in the Greater Yellowstone Ecosystem and its effects on disease dynamics

Cotterill, Gavin G.; Cross, Paul C.; Cole, Eric K.; Fuda, Rebecca K.; Rogerson, Jared D.; Scurlock, Brandon M.; Toit, Du

doi:10.1098/rstb.2017.0093

Cited by 31 publications

(39 citation statements)

References 62 publications

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“…A 24% reduction in reproductive output is substantial, but a few caveats must be considered. That value applies to seropositive females and, with periodic exceptions, it is the minority of elk within any given herd in our study area that test seropositive for brucellosis (Cotterill et al., ). Except in herds with particularly high seroprevalence, the expected decline in pregnancy probability across the herds we studied should generally be below 7%.…”

Section: Discussionmentioning

confidence: 86%

“…Data were collected in western Wyoming, south of Yellowstone National Park, USA, where supplementary winter feedgrounds are used by approximately 80% of the region's elk (Dean et al., ). The National Elk Refuge in Jackson, WY, is operated by the US Fish and Wildlife Service (USFWS) and 22 additional feedgrounds are operated by the Wyoming Game and Fish Department (WGFD; see Cotterill et al., ). Our data were collected by the WGFD for research and management purposes across all 23 feedgrounds and 2 nearby unfed wintering locations between 1995 and 2017.…”

Section: Methodsmentioning

confidence: 99%

“…The National Elk Refuge in Jackson, WY, is operated by the US Fish and Wildlife Service (USFWS) and 22 additional feedgrounds are operated by the Wyoming Game and Fish Department (WGFD; see Cotterill et al, 2018). Our data were collected by the WGFD for research and management purposes across all 23 feedgrounds and 2 nearby unfed wintering locations between 1995 and 2017.…”

Section: Study Area and Data Collectionmentioning

confidence: 99%

“…Historically, supplemental winter feedgrounds for elk in the GYE have been focal points for brucellosis contagion (Figure ). In the Wyoming portion of the southern GYE, there are 23 feedgrounds operating annually and, at times, local seroprevalence can reach as high as 60% (Cotterill et al., ). With such high exposure, one might expect that abortions should be frequent and readily observed, but on average, fewer than two fetuses were detected annually over a 50‐year period (Cross et al., ).…”

Section: Introductionmentioning

confidence: 99%

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Hidden cost of disease in a free‐ranging ungulate: brucellosis reduces mid‐winter pregnancy in elk

Cotterill

Cross

Middleton

et al. 2018

Ecology and Evolution

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Demonstrating disease impacts on the vital rates of free‐ranging mammalian hosts typically requires intensive, long‐term study. Evidence for chronic pathogens affecting reproduction but not survival is rare, but has the potential for wide‐ranging effects. Accurately quantifying disease‐associated reductions in fecundity is important for advancing theory, generating accurate predictive models, and achieving effective management. We investigated the impacts of brucellosis (Brucella abortus) on elk (Cervus canadensis) productivity using serological data from over 6,000 captures since 1990 in the Greater Yellowstone Ecosystem, USA. Over 1,000 of these records included known age and pregnancy status. Using Bayesian multilevel models, we estimated the age‐specific pregnancy probabilities of exposed and naïve elk. We then used repeat‐capture data to investigate the full effects of the disease on life history. Brucellosis exposure reduced pregnancy rates of elk captured in mid‐ and late‐winter. In an average year, we found 60% of exposed 2‐year‐old elk were pregnant compared to 91% of their naïve counterparts (a 31 percentage point reduction, 89% HPDI = 20%–42%), whereas exposed 3‐ to 9‐year‐olds were 7 percentage points less likely to be pregnant than naïve elk of their same age (89% HPDI = 2%–11%). We found these reduced rates of pregnancy to be independent from disease‐induced abortions, which afflict a portion of exposed elk. We estimate that the combination of reduced pregnancy by mid‐winter and the abortions following mid‐winter reduces the reproductive output of exposed female elk by 24%, which affects population dynamics to a similar extent as severe winters or droughts. Exposing hidden reproductive costs of disease is essential to avoid conflating them with the effects of climate and predation. Such reproductive costs cause complex population dynamics, and the magnitude of the effect we found should drive a strong selection gradient if there is heritable resistance.

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Section: Discussionmentioning

confidence: 86%

Section: Methodsmentioning

confidence: 99%

Section: Study Area and Data Collectionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Hidden cost of disease in a free‐ranging ungulate: brucellosis reduces mid‐winter pregnancy in elk

Cotterill

Cross

Middleton

et al. 2018

Ecology and Evolution

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“…However, supplemental feeding changes natural migration patterns (Peterson and Mesmer , Jones et al ) and increases stress levels (Patrek , Forristal et al ), both of which have implications for population vital rates (e.g., pregnancy rates, survival, and recruitment). Feedgrounds (i.e., high ungulate densities) also increase the potential for disease transmission and thus disease prevalence (Dean et al , Smith , Scurlock and Edwards , Smith , Cotterill et al ), which are significant concerns in regards to diseases such as brucellosis ( Brucella abortus ), which has been present in Wyoming elk for decades, and chronic wasting disease (Smith , , ; Scurlock and Edwards ; WGFD ), which was recently confirmed in a mule deer in Grand Teton National Park (~40 km from the Gros Ventre feedgrounds and ~5 km from the National Elk Refuge boundary). In theory, predators may assist with disease management by consuming diseased prey thus reducing transmission risk and prevalence by decreasing prey density across the landscape.…”

Section: Discussionmentioning

confidence: 99%

Winter predation patterns of wolves in Northwestern Wyoming

Woodruff

Jimenez

2019

J Wildl Manag

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Wolf (Canis lupus) diets and potential effects on prey have been a prominent subject of interest to wildlife researchers and managers since reintroduction into Yellowstone National Park, Wyoming, USA, in 1995 and 1996. Post‐reintroduction, wolves expanded south and recolonized areas in the southern Yellowstone ecosystem. Elk (Cervus elaphus) in this area are supplementally fed during winter (Dec–Mar) at state‐managed feedgrounds, resulting in high‐density congregations of elk. From December to March 2000–2007, we determined the winter predation patterns of wolves by examining the remains of 289 wolf kills on 3 state‐managed feedgrounds and adjacent winter range near Jackson, Wyoming. During winters 2002–2005, we also monitored the movements of radio‐collared elk on feedgrounds to describe the response of elk to the presence of wolf kills. Thirty‐seven percent (n = 106) of kills were located on elk feedgrounds where elk composition included 49% calves, 42% adult females, 5% adult males, and 5% unknown. Sixty‐three percent (n = 183) of kills were located on winter range adjacent to feedgrounds and prey species consisted of 90% elk (38% calves, 35% adult females, 24% adult males, 2% unknown), 9% moose (Alces alces; 13% calves, 69% adult females, 6% adult males, 1% unknown), 1% mule deer (Odocoileus hemionus; 1 fawn, 1 adult female), and 0.5% adult female bison (Bison bison). Mean age of elk killed on feedgrounds was 4.2 years (range = 0–20) and 4.6 years (range = 0–23) on winter range. Calves were selected more than available in most years with female elk killed less than expected. Adult males were killed more than expected in 2005–2007. Eighty‐eight percent (n = 198) of the time elk remained on the feedground even when wolves made a kill. Less commonly, elk left the feedground, gathered in larger herds on adjacent feedgrounds absent of wolves, and returned within a few days (6%, n = 13) or left the feedground for another feedground and did not return for the rest of the winter (6%; n = 14). Elk were less likely to leave feedgrounds in the presence of a wolf kill when there were more elk on that feedground. Elk left feedgrounds with greater topography and tree cover (Alkali and Fish Creek) and gathered on the flat, open feedgrounds (Patrol Cabin) more frequently than they left flat, open feedgrounds for feedgrounds with greater topography and tree cover. Our results indicate wolves in our study area primarily preyed on elk and exhibited a strong preference for elk calves. High‐density concentrations of elk on feedgrounds will continue to be an attractant for wolves. Although elk leave feedgrounds for reasons other than wolf presence, any displacement of elk from feedgrounds due to wolves will be temporary. State managers have the ability to alter management strategies (e.g., increasing wolf harvest, phasing out elk feeding, increasing the intensity of elk feeding) in an effort to affect predator‐prey relationships. © 2019 The Wildlife Society.

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Spatiotemporal epizootiology of chronic wasting disease in Wisconsin deer

Samuel

2023

Ecosphere

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Chronic wasting disease (CWD) is a fatal neurological disease of cervids caused by a misfolded protein with no vaccines or other cures to prevent infection and death. In the past decade, CWD has been recognized as one of the 10 most important challenges facing wildlife management. This paper evaluates the temporal and spatial patterns of CWD prevalence in southern Wisconsin white‐tailed deer during the past 20 years. In most CWD areas, prevalence progresses from introduction to enzootic equilibrium in 15–20 years. In some monitoring areas, the disease grows at a much slower rate and remains below the equilibrium levels. Outbreaks are characterized by four distinct epizootic stages. Disease establishment (Stage 1) depends on the distance from a CWD focus. High rates of incidence and prevalence growth (Stage 2) are followed by slower growth as the relative number of susceptible deer declines (Stage 3). The rate of prevalence increase over time is higher in more forested ecoregions and in males (0.48 vs. 0.43) but similar in females (0.43 vs. 0.37) and yearlings (0.44 vs. 0.39). Habitat features, acting as surrogates for deer behavior and contact, may affect the rate of prevalence growth at a landscape (ecoregion) scale. Additionally, prevalence may be affected by deer management practices that favor higher deer abundance and more mature males. Finally, enzootic equilibrium (Stage 4) is higher in males (0.5), followed by females (0.36) and then yearlings (0.26). These equilibrium prevalence levels are high enough to have significant population impacts, reduce the abundance of mature males, and facilitate CWD spread by infected yearlings. Epizootic patterns suggest that CWD transmission has been frequency‐dependent and primarily driven by direct contact with infected deer. Evidence for a meaningful change in the epizootic pattern from a 10‐year management program to reduce deer abundance is lacking. The trajectory of CWD dynamics in Wisconsin suggests rapid growth in regional prevalence following introduction and increased spread across the landscape.

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Winter feeding of elk in the Greater Yellowstone Ecosystem and its effects on disease dynamics

Cited by 31 publications

References 62 publications

Hidden cost of disease in a free‐ranging ungulate: brucellosis reduces mid‐winter pregnancy in elk

Hidden cost of disease in a free‐ranging ungulate: brucellosis reduces mid‐winter pregnancy in elk

Winter predation patterns of wolves in Northwestern Wyoming

Spatiotemporal epizootiology of chronic wasting disease in Wisconsin deer

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