Aging Experience, Accuracy, and Precision

Matson’s experience level varies among different mammal species. We currently process approximately 100,000 – 115,000 teeth annually with a trend of steady increase. Last tabulated through December 2019, the count of teeth aged in our laboratory was 2,662,583, broken down by species as follows:

SpeciesTotal Aged 1978 – 2019Oldest Age to DateOrigin
Bear, black786,00835Idaho
Bear, brown/grizzly70,75439Alaska
Beaver16N Territories
Bison4,50522N Territories
Boar, wild5611Spain
Bobcat225,99523New Mexico
Caribou47,33322Alaska, N Territories (tie)
Deer, black-tailed51,13322Oregon
Deer, mule132,95320Washington
Deer, roe1,89715Belgium
Deer, sika4,69418Japan
Deer, white-tailed327,04522Louisiana
Deer, red3,34920Spain
Fox, gray13California
Fox, red16Sweden
Fox, silver10Labrador
Goat, mountain22,36718British Columbia
Lion, mountain75,66222Montana
Moose167,33522New Brunswick
Muskox1,26717N Territories
Otter, river51,69419Connecticut
Otter, sea22,90820Alaska
Pronghorn18,59417North Dakota
Sheep, bighorn4,57517British Columbia
Skunk, striped9,74212West Virginia
Weasel/Stoat7887New Zealand
Wolf12,03915N Territories
Wolverine5,91713N Territories
Other species28,710

To encourage continuing accuracy evaluation, Matson’s processes all teeth from known age animals without charge, providing the results can be shared in our periodic reports. Although we continue to collect accuracy and precision data, a thorough tabulation has not been made since 1998 and we expect new data to differ very little from those presented here. Known age material is not available to fully evaluate accuracy in most species, with exceptions being Alaska brown bear and Rocky Mountain elk.

Cementum aging accuracy can be expected to vary not only among different species and populations, but also among individuals in the same population. However, the evidence below indicates that most species should be aged with an accuracy of 70%, and 90% will be within 1 year of the correct age. For species that are difficult to analyze, 50% should be aged accurately and 85% will be within 1 year of the correct age.

Species with the most distinct cementum annuli occurring in the most regular pattern are expected to be the most accurately aged.
The following groupings reflect expected aging accuracy based on cementum characteristics.

High Accuracy (95%)
Annuli very distinct, pattern very regular
Moderate (80-90%)
Annuli and pattern somewhat distinct and regular
Low Accuracy (70-75%)
Annuli indistinct, pattern irregular
BadgerBear*BisonMountain lion
FisherBlack-tailed deer*Bobcat*Sea otter
  Mule Deer*Muskox  
  River OtterSheep  
  White-tailed deer*Wolf  

*Populations are variable, with some having cementum characteristics that yield high accuracy (e.g. Rocky Mountain elk, northern deer populations) and others that yield moderate accuracy (e.g. southern whitetail deer, southwestern mule deer, coastal elk). Supplementally fed animals have cementum annuli that are more complex and irregular than wild populations, which may lower the reliability of age analysis. For more information about supplemental feeding, see the Accuracy section of our Hunter & Outfitter page.

To end of 1996
SpeciesNumberAged CorrectlyError ± 1 yearError > 1 yearAverage Age
Alaska brown bear77522234
Rocky Mountain elk5251104
Various 1975-9547733110324
To end of 199660643412627
SpeciesNumberAged CorrectlyError ± 1 yearError > 1 yearAverage Age
Montana mule deer76104
Montana elk1312105
Illinois white-tail99001.7
Sea otter*30309
*Three were analyzed “blind” from the same known-age sea otter. The known age was 9 years.
The cementum ages for the 3 teeth were 8A(8-9), 8A(8-9), and 10A(9-10).
SpeciesNumberAged CorrectlyError ± 1 yearError > 1 yearAverage Age
Montana elk440010
Montana mule deer110010
Michigan white-tail67501614
Minnesota white-tail109104
Illinois white-tail66002

To encourage continuing precision evaluation, Matson’s processes blind duplicates without charge, providing the results can be shared in our periodic reports. We will analyze a number of blind duplicates totaling up to 10% of the sample size, not to exceed 50 teeth (e.g. in a sample of 100 teeth, 10 blind duplicates will be processed free of charge). Although we continue to collect precision data, a thorough tabulation has not been made since 1998. Ongoing evaluations show precision continuing at levels observed in the past.

In the absence of known age teeth, precision measurements using blind pairs provide useful information because differing results for a pair are proof of error. Results of precision tests with blind duplicates follow (please note that accuracy for these species is expected to be moderate or low because of cementum characteristics).

YearSpeciesNumberAged CorrectlyError ± 1 yearError > 1 year
1995-96Mountain lion72372510
1996Mountain lion6600
1997Black bear4400
1997Mountain lion13733
1998Marten PM19564256
1998Grizzly bear242022
1998White-tailed deer181242