Estimating ages of white-tailed deer: Age and sex patterns of error using tooth wear-and-replacement and consistency of cementum annuli

Abstract

The age structure of harvested animals provides the basis for many demographic analyses. Ages of harvested white-tailed deer (Odocoileus virginianus) and other ungulates often are estimated by evaluating replacement and wear patterns of teeth, which is subjective and error-prone. Few previous studies however, examined age-and sex-specific error rates. Counting cementum annuli of incisors is an alternative, more accurate method of estimating age, but factors that influence consistency of cementum annuli counts are poorly known. We estimated age of 1,261 adult (!1.5 yr old) white-tailed deer harvested in Wisconsin and Illinois (USA; 2005-2008) using both wear-and-replacement and cementum annuli. We compared cementum annuli with wear-and-replacement estimates to assess misclassification rates by sex and age. Wear-and-replacement for estimating ages of white-tailed deer resulted in substantial misclassification compared with cementum annuli. Age classes of females were consistently underestimated, while those of males were underestimated for younger age classes but overestimated for older age classes. Misclassification resulted in an impression of a younger age-structure than actually was the case. Additionally, we obtained paired age-estimates from cementum annuli for 295 deer. Consistency of paired cementum annuli ageestimates decreased with age, was lower in females than males, and decreased as age estimates became less certain. Our results indicated that errors in the wear-and-replacement techniques are substantial and could impact demographic analyses that use age-structure information. Ó 2014 The Wildlife Society.

Chronic wasting disease in white‐tailed deer: infection, mortality, and implications for heterogeneous transmission

“…For males, ages of deer placed into the TRW age classes 1 and 2 were underestimated, while the TRW age class of deer in age classes 3 and older was generally overestimated (Storm et al. ). We used cumulative logit models to correct TRW ages of both CWD negative and positive deer and calculate corrected CWD age‐prevalence estimates.…”

“…We used separate logit models for each state and for males and females because there were differences in misclassification between sexes and age categories used by each state (Storm et al. ). We also used binomial and multinomial models to correct age misclassification, but the results were very similar to those from the cumulative logit model (results not shown).…”

“…However, age misclassification in wildlife populations can often lead to biased age estimates (Conn and Diefenbach , Storm et al. ) and potential bias in these important epidemiological parameters. For some wildlife, young animals are often misclassified as older, while adults may be misclassified as younger (Coy and Garshelis , Harshyne et al.…”

“…Recently, Storm et al. () found substantial misclassification in the TRW ages compared to CA for WTD harvested in Wisconsin and Illinois, including differential bias for males and females, and used a multinomial correction method for calculating a corrected age distribution.…”

Individual variation in dental characteristics for estimating age of African lions

“…Crown wear scores were largely consistent between paired teeth, with most PM 2 s having smoothed edges and moderate wear. However, scoring of wear is qualitative and assignment of teeth to age classes (three in this study) as opposed to a specific age inherently reduces variability (Storm et al 2014). Lion PM 2 s are relatively protected in the maxillary tooth row, wear gradually (Smuts et al 1978, Whitman andPacker 2007), and exhibit the least amount of damage compared to other tooth types (Van Valkenburgh 1988, Patterson et al 2003.…”