Northern Prairie Wildlife Research Center
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
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.
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