The effect of sex, age, and location on carnivory in Utah black bears (Ursus americanus)
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Ungulates are important to the diet of bears because they are high in protein, and the level of dietary protein strongly influences bear size. The size a bear obtains as an adult influences important life history characteristics, such as age of reproduction and reproductive success; therefore, it is important to know what foods are available to bears and how they are utilizing them. We tested hypotheses concerning the effect of age, sex, and location on black bear carnivory. We collected hair and vestigial premolar teeth from 49 Utah black bears, Ursus americanus according to the Utah Division of Wildlife Resources hunt unit. Hunt units differed in habitat quality and local ungulate density. We analyzed a vestigial premolar for the age of the bears and used analysis of the δ13C and δ15N values of the hairs of each bear to infer the degree of carnivory. δ15N of black bear hairs was positively correlated with increased availability of ungulates. There was a positive relationship between the δ15N of bear hairs and age in hunt units with the highest ungulate densities only. The δ15N and δ13C of black bear hairs were positively correlated, suggesting that bears are more carnivorous at higher altitudes. This study demonstrates the value of stable isotope analysis in understanding the feeding ecology of bears over broad geographic ranges. It demonstrates that ungulate availability is important to the feeding ecology of black bears in the Intermountain West.
KeywordsStable isotopes Trophic level Carbon Nitrogen Ungulates
We would like to acknowledge the help of all the hunters who submitted hair and vestigial tooth samples to the Utah DWR and the assistance of the Utah DWR in collecting those samples and the associated data. We thank Craig McLaughlin, now at the Colorado Division of Parks and Wildlife, for locating ungulate counts for hunt units. Finally, we would like to thank Amanda Loveless, Hailey Billings, Eric Olson, Joycelyn, and Vanessa Dewey for their help in prepping samples.
Author contribution statement
KAH was primarily responsible for originating the idea behind the paper, the experimental design, stable isotope analysis of hair samples, data analysis, wrote substantial portions of the paper, and closely supervised and mentored KAK. KAK revised and rewrote significant portions of the paper and did significant library research to expand and update the citations in the manuscript. BLR, HB, and JA contributed significantly to the process of designing the experiment with BLR helping with stable isotope analysis of hair samples and revisions of the manuscript HB and JA helped extensively with arranging contacts with individuals at the Utah Department of Wildlife Resources (UDWR), obtaining data and maps from the UDWR and arranging the data for analysis, and revising the manuscript. KB arranged for the collection of hair and teeth samples from Utah bear hunters, the analysis of the teeth for aging, obtaining hunt unit maps of Utah, obtaining hunt unit data on bears killed within hunt units, ungulate numbers within hunt units, and hunt unit areas.
- Bunnell ST (2000) Spring and summer diet and feeding behavior of black bears on the East Tavaputs Plateau, Utah. M.S. Thesis, Brigham Young University, Provo, Utah, USAGoogle Scholar
- Bunnell F, Tait D (1981) Population dynamics of bears—implications. Dynamics of large mammal populations. Wiley, New York, pp 7–98Google Scholar
- Chen L, Flynn DFB, Zhang X, Gao X, Lin L, Luo J, Zhao C (2014) Divergent patterns of foliar δ13C and δ15N in Quercus aquifolioides with an altitudinal transect on the Tibetan Plateau: an integrated study based on multiple key leaf functional traits. J Plant Ecol 8(3):303–312. https://doi.org/10.1093/jpe/rtu020 CrossRefGoogle Scholar
- D’Eon RG, Serrouya R (2005) Mule deer seasonal movements and multiscale resource selection using global positioning system radiotelemetry. J Mammal 86(4):736–744. https://doi.org/10.1644/1545-1542(2005)086%5b0736:MDSMAM%5d2.0.CO;2 CrossRefGoogle Scholar
- Dykstra EA (2015) Using stable isotope analysis to estimate black bear (Ursus americanus) diet in Vermont. University of Vermont, Graduate College Dissertations and Theses. Paper 388Google Scholar
- Feng QH, Cheng RM, Shi ZM, Liu SR, Liu XL, He F, Cao HM (2011) Effects of altitudinal gradient on Salix atopantha foliar δ13C. Chin J Appl Ecol 22(11):2841–2848Google Scholar
- Graber DM, White M (1983) Black bear food habits in Yosemite National Park. In: A selection of papers from the fifth international conference on bear research and management, 5(1):1–10Google Scholar
- Hewitt DG, Robbins CT (1996) Estimating grizzly bear food habits from fecal analysis. Wildl Soc Bull 24(3):547–550Google Scholar
- Hilderbrand GV, Schwartz CC, Robbins CT, Jacoby ME, Hanley TA, Arthur SM, Servheen C (1999b) The importance of meat, particularly salmon, to body size, population productivity, and conservation of North American brown bears. Can J Zool 77(1):132–138. https://doi.org/10.1139/z98-195 CrossRefGoogle Scholar
- McDonald JE Jr, Fuller TK (1999) Black bear food habits: beyond the same old scats. NCASI Tech Bull 781(I):335Google Scholar
- Rogers LL (1987) Effects of food supply and kinship on social behavior, movements, and population growth of black bears in northeastern Minnesota. Wildl Monogr 97:3–72Google Scholar
- Servheen C, Herrero S, Peyton B (1999) Bears: status survey and conservation action plan: IUCN/SSC Bear Specialist GroupGoogle Scholar
- Welch CA, Keay J, Kendall KC, Robbins CT (1997) Constraints on frugivory by bears. Ecology 78(4):1105–1119. https://doi.org/10.1890/0012-9658(1997)078[1105:COFBB]2.0.CO;2 CrossRefGoogle Scholar