---

Accuracy and Precision of Estimating Age of
Gray Wolves by Tooth Wear

Philip S. Gipson¹, Warren B. Ballard², Ronald M. Nowak³, L. David Mech⁴

---

Abstract:  We evaluated the accuracy and precision of tooth wear for aging gray wolves (Canis lupus) from Alaska, Minnesota, and Ontario based on 47 known-age or known-minimum-age skulls. Estimates of age using tooth wear and a commercial cementum annuli-aging service were useful for wolves up to 14 years old. The precision of estimates from cementum annuli was greater than estimates from tooth wear, but tooth wear estimates are more applicable in the field. We tended to overestimate age by 1-2 years and occasionally by 3 or 4 years. The commercial service aged young wolves with cementum annuli to within ±1 year of actual age, but under estimated ages of wolves ≥9 years old by 1-3 years. No differences were detected in tooth wear patterns for wild wolves from Alaska, Minnesota, and Ontario, nor between captive and wild wolves. Tooth wear was not appropriate for aging wolves with an underbite that prevented normal wear or severely broken and missing teeth.

Key Words:  Age estimation, Canis lupus, tooth wear, wolf.

---

This resource is based on the following source:

Gipson, Philip S., Warren B. Ballard, Ronald M. Nowak, and L. David Mech.  
     2000.  Accuracy and precision of estimating age of gray wolves by 
     tooth wear.  Journal of Wildlife Management 64(3):752-758.

This resource should be cited as:

Gipson, Philip S., Warren B. Ballard, Ronald M. Nowak, and L. David Mech.  
     2000.  Accuracy and precision of estimating age of gray wolves by 
     tooth wear.  Journal of Wildlife Management 64(3):752-758.  
     Jamestown, ND: Northern Prairie Wildlife Research Center Online. 
     http://www.npwrc.usgs.gov/resource/mammals/toothage/index.htm  
     (Version 30APR2001).

---

Table of Contents

• Introduction
• Methods
• Results
  • Precision and Accuracy
  • Progressive Tooth Wear
• Discussion
• Management Implications
• Literature Cited

Tables and Figures

• Table 1 -- Skulls of wolves from Alaska used to define year age classes.
• Table 2 -- Linear regression analysis relating estimated age to known age wolves from Minnesota and Ontario.
• Table 3 -- Wear on teeth of wolves associated with increasing age (yr).

• Figure 1 -- Progressive wear on wolf incisors and canines in 2-year increments from ≤1 to ≥12 years of age.
• Figure 2 -- Progressive wear on wolf carnassials in 2-year increments from ≤6 to ≥12 years of age.
• Figure 3 -- Age bias graphs for 3 readers showing estimates of ages of 20 wolves from Minnesota and Ontario compared to known ages-.
• Figure 4 -- Age bias graphs for a consensus of the 3 tooth-wear readers and a commercial aging service using counts of cementum annuli to estimate ages of 20 wolves from Minnesota and Ontario compared to known ages.

---

¹ Kansas Cooperative Fish and Wildlife Research Unit, U.S. Geological Survey, Division of Biology, Leasure Hall, Room 205, Kansas State University, Manhatten, KS 66506, USA

² Department of Range, Wildlife and Fisheries Management, Box 42125, Texas Tech University, Lubbock, TX 79409, USA

³ U.S. Fish and Wildlife Service, 4401 North Fairfax Drive, Room 750, Arlington, VA 22203, USA
Present address:  2101 Greenwich Street, Falls Church, VA 22043, USA.

⁴ Biological Resources Division, U.S. Geological Survey, Northern Prairie Wildlife Research Center, 8711 37th Street, Jamestown, ND 58401, USA
Mailing address:  North Central Research Station, 1992 Folwell Avenue, St. Paul, MN 55108, USA.

---

NPWRC Home�|�Site�Map�|�About Us�|�Staff�|�Search�|�Contact�|�Web�Help�|�Copyright