Using Molar Attrition to Age Live Prairie Dogs

Abstract

Molar attrition was examined in 153 live black-tailed prairie dogs (Cynomys ludovicianus) of known ages determined from a history of permanently marked juveniles. Based on tooth wear, molars were assigned to 3 age classes: 0.5, 1.5, and -2.5 years. Molar attrition predicted the correct age class for 86% (131 + 153) of individuals. J. WILDL. MANAGE. 51(2):393-394 Several mammalian aging techniques are available, but most of these require maiming or killing of individuals (reviewed by Sherman et al. [1985]). One nondestructive method of aging wild mammals involves examining patterns of wear on molar teeth, which in most species are permanent and do not continue to grow after physical maturity (Vaughan 1978). Molars with little attrition (i.e., high cusps) indicate young animals and molars with extensive attrition (i.e., low cusps) indicate older animals. A major advantage of this method is speed, requiring only seconds to score each restrained individual. Aging by molar attrition compares favorably with estimates of age based on counts of cementum layers in teeth of several species; e.g., see Lockard (1972). However, rarely has aging by molar attrition been rigorously compared with known ages determined from tracking of marked juveniles over time, and all these comparisons have involved cervids; e.g., see Quimby and Gaab (1957). We evaluated molar attrition of black-tailed prairie dogs of known ages as a means to accurately and quickly age live individuals in the field. We thank the 105 field assistants who have helped over the years, especially J. G. Hoogland, M. V. Hoogland, S. T. Hoogland, J. Herron, G. Koscielny, and K. Roam. M. G. Garrett helped us to devise the method for categorizing molar attrition. For financial assistance, we thank The Natl. Sci. Found., The Natl. Geogr. Soc., The Am. Philos. Soc., The Cent. Field Res., The Eppley Found. for Res., The Harry Frank Guggenheim Found., The Max McGraw Wildl. Found., The Am. Soc. Mammal., The Univ. Maryland, Michigan, and Minnesota, and Princeton Univ. We also thank the staff at Wind Cave Natl. Park, especially L. F. McClanahan, J. Randall, E. Ortega, and R. Klukas. For help with the manuscript, we thank J. Barlow, H. Broadbrooks, S. Fancy, J. E. Gates, K. R. McKaye, C. Phillips, and D. I. Rubenstein. This paper is Sci. Ser. No. 1729-AEL from The Univ. Maryland's Cent. for Environ. and Estuarine Stud.