Body condition and pregnancy in northern Yellowstone elk: Evidence for predation risk effects?
Open accessAbstract
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 (1962-1968) and after (2000-2006) 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%-0.9% pre-wolf; 8.9%-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 = -0.15 to 0.03, P = 0.46) and 0.64 pre-wolf and 0.78 post-wolf for elk > 9 years old (95% CI on difference = -0.01 to 0.27, P = 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.
The claims and statistics of this paper haven’t been checked yet.
Run the check — free, no account needed. It reads the open-access text and checks the sources it cites.
Integrity signals
Registry
Cites
Statistics
Claims the paper makes
The claims and statistics of this paper haven’t been checked yet.
Run the check — free, no account needed. It reads the open-access text and checks the sources it cites.
Claims other papers make about this one
Each is checked against this paper’s own text: does it say what the citing paper says it does?
Recent work found no differences in body fat levels and pregnancy rates of Yellowstone elk before and after wolf reintroduction.
“recent work found no differences in the body fat levels and pregnancy rates of Yellowstone elk before and after wolf reintroduction (White et al. 2011).”
From Animal migration amid shifting patterns of phenology and predation: lessons from a Yellowstone elk herd (2013) · cites this paper as White et al. 2011
The Abstract reports nearly identical age-adjusted body fat before and after wolf restoration, and the Results report similar pregnancy rates for elk aged 4–9 years. But the Results also report higher post-wolf body fat and pregnancy rates for elk older than 9 years. Thus, saying there were no differences across Yellowstone elk overgeneralizes the findings. (LLM, conf=0.89)
Experimental — accuracy not yet measured
Self-check
Percentages, sums and reported differences re-computed from the paper’s own numbers.
The self-check needs the paper’s full text.
No citation lists for this paper
No citation lists for this paper yet — checked again daily.
References 40 · Cited by 56
Research works printed but not linked: 30
- Anderson, A. E., D. E. Medin, and D. C. Bowden. 1972. Indices of carcass fat in a Colorado mule deer population. Journal of Wildlife Management 36:579-594.
- Cook, R. C., J. G. Cook, R. A. Garrott, L. L. Irwin, and S. L. Monfort. 2002. Effects of diet and body condition on fecal progestagen excretion in elk. Journal of Wildlife Diseases 38: 558-565.
- Cook, R. C., J. G. Cook, and L. L. Irwin. 2003. Estimating elk body mass using chest-girth circumference. Wildlife Society Bulletin 31:536-543.
- Cook, R. C., J. G. Cook, and L. D. Mech. 2004b. Nutritional condition of northern Yellowstone elk. Journal of Mammal- ogy 85:714-722.
- Cook, R. C., J. G. Cook, D. L. Murray, P. Zager, B. K. Johnson, and M. W. Gratson. 2001a. Development of predictive models of nutritional condition for Rocky Mountain elk. Journal of Wildlife Management 65:973-987.
- Cook, R. C., J. G. Cook, D. L. Murray, P. Zager, B. K. Johnson, and M. W. Gratson. 2001b. Nutritional condition models for elk: which are the most sensitive, accurate, and precise? Journal of Wildlife Management 65:988-997.
- Cook, R. C., J. G. Cook, T. R. Stephenson, W. L. Myers, S. M. McCorquodale, D. J. Vales, L. L. Irwin, P. B. Hall, R. D. Spencer, S. L. Murphie, K.A. Schoenecker, and P. J. Miller. 2010. Revisions of rump fat and body scoring nutritional condition indices for deer, elk, and moose. Journal of Wildlife Management 74:880-896.
- Fuller, T. K., L. D. Mech, and J. F. Cochrane. 2003. Wolf population dynamics. Pages 161-191 in L. D. Mech and L. Boitani, editors. Wolves: behavior, ecology, and conserva- tion. University of Chicago Press, Chicago, Illinois, USA. January 2011 7
- PREDATION RISK EFFECTS ON ELK PREGNANCY C ommunications 19395582, 2011, 1, Downloaded from https://esajournals.onlinelibrary.wiley.com/doi/10.1890/09-2123.1, Wiley Online Library on [28/04/2025]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License
- Garrott, R. A., L. L. Eberhardt, P. J. White, and J. Rotella. 2003. Climate-induced variation in vital rates of an unhar- vested large herbivore population. Canadian Journal of Zoology 81:33-45.
- Garrott, R. A., S. L. Monfort, P. J. White, K. L. Mashburn, and J. G. Cook. 1998. One-sample pregnancy diagnosis in elk using fecal steroid metabolites. Journal of Wildlife Diseases 34:126-131.
- Garrott, R. A., P. J. White, and J. J. Rotella. 2009a. The Madison headwaters elk herd: stability in an inherently variable environment. Pages 191-216 in R. A. Garrott, P. J. White, and F. Watson, editors. The ecology of large mammals in central Yellowstone: sixteen years of integrated field studies. Elsevier, San Diego, California, USA.
- Garrott, R. A., P. J. White, and J. J. Rotella. 2009b. The Madison headwaters elk herd: transitioning from bottom-up regulation to top-down limitation. Pages 489-517 in R. A. Garrott, P. J. White, and F. Watson, editors. The ecology of large mammals in central Yellowstone: sixteen years of integrated field studies. Elsevier, San Diego, California, USA.
- Geremia, C., P. J. White, R. A. Garrott, R. Wallen, K. E. Aune, J. Treanor, and J. A. Fuller. 2009. Demography of central Yellowstone bison: effects of climate, density and disease. Pages 255-279 in R. A. Garrott, P. J. White, and F. G. R. Watson, editors. The ecology of large mammals in central Yellowstone: sixteen years of integrated field studies. Elsevier, San Diego, California, USA.
- Gower, C. N., R. A. Garrott, and P. J. White. 2009a. Elk foraging behavior: does predation risk reduce time for food acquisition? Pages 423-450 in R. A. Garrott, P. J. White, and F. Watson, editors. The ecology of large mammals in central Yellowstone: sixteen years of integrated field studies. Elsevier, San Diego, California, USA.
- Gower, C. N., R. A. Garrott, P. J. White, F. G. Watson, S. Cornish, and M. S. Becker. 2009b. Spatial responses of elk to winter wolf predation risk: using the landscape to balance multiple demands. Pages 373-399 in R. A. Garrott, P. J. White, and F. Watson, editors. The ecology of large mammals in central Yellowstone: sixteen years of integrated field studies. Elsevier, San Diego, California, USA.
- Hamlin, K. L., R. A. Garrott, P. J. White, and J. A. Cunningham. 2009. Contrasting wolf-ungulate interactions in the Greater Yellowstone Ecosystem. Pages 541-577 in
- R. A. Garrott, P. J. White, and F. Watson, editors. The ecology of large mammals in central Yellowstone: sixteen years of integrated field studies. Elsevier, San Diego, California, USA.
- Hamlin, K. L., D. F. Pac, C. A. Sime, R. M. Desimone, and G. L. Dusek. 2000. Evaluating the accuracy of ages obtained by two methods for montane ungulates. Journal of Wildlife Management 64:441-449.
- Kohlmann, S. J. 1999. Adaptive fetal sex allocation in elk: evidence and implications. Journal of Wildlife Management 63:1109-1117.
- Lemke, T. O., J. A. Mack, and D. B. Houston. 1998. Winter range expansion by the northern Yellowstone elk herd. Intermountain Journal of Sciences 4:1-9.
- Mao, J. S., M. S. Boyce, D. W. Smith, F. J. Singer, D. J. Vales, J. M. Vore, and E. H. Merrill. 2005. Habitat selection by elk before and after wolf reintroduction in Yellowstone National Park. Journal of Wildlife Management 69:1691-1707.
- Merrill, E. H., and M. S. Boyce. 1991. Summer range and elk population dynamics in Yellowstone National Park. Pages 263-273 in R. B. Keiter and M. S. Boyce, editors. The greater Yellowstone ecosystem: redefining America's wilderness her- itage. Yale University Press, New Haven, Connecticut, USA.
- Noyes, J. H., R. G. Sasser, B. K. Johnson, L. D. Bryant, and B. Alexander. 1997. Accuracy of pregnancy detection by serum protein (PSPB) in elk. Wildlife Society Bulletin 25:695-698.
- Raedeke, K. J., J. J. Millspaugh, and P. E. Clark. 2002. Population characteristics. Pages 449-491 in D. E. Toweill and J. W. Thomas, editors. North American elk: ecology and management. Smithsonian Institution Press, Washington, D.C., USA.
- Rhyan, J. C., K. Aune, T. Roffe, D. Ewalt, S. Hennager, T. Gidlewski, S. Olsen, and R. Clarke. 2009. Pathogenesis and epidemiology of brucellosis in Yellowstone: serologic and culture results from adult females and their progeny. Journal of Wildlife Diseases 45:729-739.
- Taper, M. L., and P. J. P. Gogan. 2002. The northern Yellowstone elk: density dependence and climatic conditions. Journal of Wildlife Management 66:106-122.
- White, P. J., R. A. Garrott, S. Cherry, F. G. R. Watson, C. N. Gower, M. S. Becker, and E. Meredith. 2009. Changes in elk resource selection and distribution with the reestablishment of wolf predation risk. Pages 451-476 in R. A. Garrott, P. J. White, and F. Watson, editors. The ecology of large mammals in central Yellowstone: sixteen years of integrated field studies. Elsevier, San Diego, California, USA.
- White, P. J., R. A. Garrott, J. F. Kirkpatrick, and E. V. Berkeley. 1995a. Diagnosing pregnancy in free-ranging elk using fecal steroid metabolites. Journal of Wildlife Diseases 31:514-522.
- White, P. J., R. A. Garrott, C. A. Vanderbilt White, and G. A. Sargeant. 1995b. Interpreting mean snow-urine ratios from simple random collections. Wildlife Society Bulletin 23:705- 710.
- Authors
- White, P. J., Garrott, R. A., Hamlin, K. L., Cook, R. C., Cook, J. G., & Cunningham, J. A.
- Affiliations
- National Park Service (US)
- Montana State University (US)
- Montana Fish, Wildlife & Parks (US)
- National Council for Air and Stream Improvement (US)
- Corresponding author
- White, P. J.
- Venue
- Ecological Applications
- Publisher
- Wiley
- Published
- 2011-01
- Volume
- 21
- Issue
- 1
- Pages
- 3-8
- ISSN
- 1051-0761 (ISSN-L)
- OpenAlex
- W2110648469
- Cited by
- 56
- References
- 40
- Citations by year
- 2026: 2 · 2025: 1 · 2024: 2 · 2023: 1 · 2022: 2 · 2021: 2 · 2020: 4 · 2019: 3 · 2018: 5 · 2017: 3 · 2016: 6 · 2015: 3 · 2014: 9 · 2013: 9 · 2012: 1
- FWCI
- 5.93
- Type
- journal article
- Language
- en
- Open access
- bronze
- doi.org
- Locations
- Ecological Applications (publishedVersion)
- PubMed (publishedVersion)
- Funders
- National Science Foundation (0716188)
- U.S. Geological Survey
- National Park Service
- Natural Sciences and Engineering Research Council of Canada
- Topics
- Physical Sciences › Environmental Science › Ecology › Wildlife Ecology and Conservation
- Physical Sciences › Environmental Science › Ecology › Rangeland and Wildlife Management
- Physical Sciences › Environmental Science › Ecology › Animal Ecology and Behavior Studies
- Keywords
- elk, red deer, wolf reintroduction, wolf, predation risk, pregnancy rate, body condition, fat mass, fecal progesterone, forage intake, Rocky Mountain elk, Yellowstone National Park
- MeSH terms
- Animals, Body Composition, Carnivora, Deer, Female, Humans, Predatory Behavior, Pregnancy, Pregnancy, Animal
About these checks
Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.
Statistics and arithmetic are recomputed, not judged.
Confidence bands are shown only for fields calibrated on our annotated test set. None is calibrated yet, so no band is shown.
What counts as a claim ›How we measure confidence ›How we check this ›
Are you an author, or do you see a problem with this page? Request a review
