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Calhoun TJ, Mesa-Cruz JB, Holcombe BE, Osborn DA, D’Angelo GJ, Lafon N, Kelly MJ. Splitting hairs: differentiating juvenile from adult deer ( Odocoileus virginianus) by hair width. J Mammal 2022. [DOI: 10.1093/jmammal/gyac111] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Abstract
Ungulates are a main component in carnivore diets but determining consumption of juveniles is difficult. Past studies have used size of prey remains such as small hooves or bones to classify scat samples as containing content attributable to juveniles. Hair thickness and color may also be used, but seasonality could influence the coat of an adult by developing thinner hairs in summer that more closely resemble those from juveniles. Given this uncertainty, we aimed to quantitatively determine a hair diameter threshold to categorize the age-class of ungulate hair in scats. We obtained hair samples from captive (n = 133) and vehicle-killed (n = 5) white-tailed deer (Odocoileus virginianus) from Georgia and Virginia. We used microphotography image analysis to measure the width of hairs and their cuticular casts. We used a linear model to assess differences among body locations, age-classes, and locations along the hair strand. We also analyzed the change in hair width of juveniles as they aged. Hair diameter of adults, but not juveniles, differed significantly depending on body location, yet adult hairs were always significantly wider than those from juveniles. Juvenile hairs significantly increased in width after mid-September, when they molt into adult coats in our study area. We identified 104.2 µm measured at either 1/8 or 1/4 distance from the follicle as a threshold width to distinguish adult from juvenile hairs, with 95.3% accuracy. Our findings indicate that juvenile white-tailed deer can be distinguished from adults based on the width of hairs found in carnivore scats up until juveniles are 5 months old. More broadly, our results demonstrate that hair width may be used to classify juvenile versus adult prey remains in carnivore diet studies in other predator–prey systems.
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Affiliation(s)
- Timothy J Calhoun
- Department of Fish and Wildlife Conservation, Virginia Polytechnic Institute and State University , Blacksburg, Virginia , USA
| | - J Bernardo Mesa-Cruz
- Department of Fish and Wildlife Conservation, Virginia Polytechnic Institute and State University , Blacksburg, Virginia , USA
- Integrative Sciences, Harrisburg University , Harrisburg, Pennsylvania , USA
| | - Brogan E Holcombe
- Department of Fish and Wildlife Conservation, Virginia Polytechnic Institute and State University , Blacksburg, Virginia , USA
| | - David A Osborn
- Warnell School of Forestry and Natural Resources, University of Georgia , Athens, Georgia , USA
| | - Gino J D’Angelo
- Warnell School of Forestry and Natural Resources, University of Georgia , Athens, Georgia , USA
| | - Nelson Lafon
- Virginia Department of Wildlife Resources , Forest, Virginia , USA
| | - Marcella J Kelly
- Department of Fish and Wildlife Conservation, Virginia Polytechnic Institute and State University , Blacksburg, Virginia , USA
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Nipko RB, Holcombe BE, Kelly MJ. Identifying Individual Jaguars and Ocelots via Pattern‐Recognition Software: Comparing HotSpotter and Wild‐ID. WILDLIFE SOC B 2020. [DOI: 10.1002/wsb.1086] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Robert B. Nipko
- Department of Fish and Wildlife Conservation—Virginia Tech 310 W Campus Drive Blacksburg VA 24061 USA
| | - Brogan E. Holcombe
- Department of Fish and Wildlife Conservation—Virginia Tech 310 W Campus Drive Blacksburg VA 24061 USA
| | - Marcella J. Kelly
- Department of Fish and Wildlife Conservation—Virginia Tech 310 W Campus Drive Blacksburg VA 24061 USA
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