Aging Experience, Accuracy and Precision

Matson's experience level varies among different mammal species. We currently process approximately 90,000 – 100,000 teeth annually with a trend of steady increase. Last tabulated through September, 2017 the count of teeth aged in our laboratory was 2,385,266, broken down by species as follows:

Species
Jan 1978 thru Sept
2017
 

 

Oldest
(yr)
to
Current
Date
From
Badger
1,544
19
Washington
Bear, black
696,327
35
Idaho
Bear, Brown (Grizzly)

65,740

39
Alaska
Bison
4,391
22
N Territories
Boar, wild
69
11
Spain
Bobcat
205,774
23
New Mexico
Caribou
46,283
22
Alaska
Coyote
23,718
15
Colorado
Deer, black-tailed
48,953
22
Oregon
Deer, mule
122,218
20
Washington
Deer, roe
1,897
15
Belgium
Deer, sika
4,452
18
Japan
Deer, white-tailed
281,538
22
Louisiana
Elk
180,268
32
Pennsylvania
Deer, red
3,344
20
Spain
Fisher
23,399
9
-Manitoba
Fox
23,325
-
-
Fox, gray
-
13
California
Fox, red
-
16
Sweden
Fox, silver
-
10
Labrador
Goat, mountain
21,364
18
British Columbia
Lion, mountain
65,351
22
Montana
Lynx
17,798
18
Switzerland
Marten
73,355
16
Alaska
Mink
14,115
10
France
Moose
153,703
22
New Brunswick
Muskox
1,178
17
N Territories
Otter, river
44,984
19
Connecticut
Otter, sea
22,390
20
Alaska
Pronghorn
16,829
17
North Dakota
Raccoon
152,414
19
Maryland
Seal
13,817
42
Ontario
Sheep, bighorn
3,835
17
British Columbia
Skunk, striped
7,633
12
West Virginia
Weasel, stoat
788
7
New Zealand
Wolf
10,984
15
N Territories
Wolverine
5,504
13
N Territories
Other species
23,778
-
-
TOTAL
2,385,266
  

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 tabluation has not been made since 1998. 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. Exceptions are Alaska Brown Bear and Rocky Mountain Elk.

Number
Sample
Aged correctly
Error + or - 1 yr
Error more than 1 yr
Average age
To end of 1996
77
Alaska Brn Bear
52
22
3
4
52
Rocky Mt Elk
51
1
0
4
477
Various 1975-95
331
103
24
--
606
to end 1996
434
126
27
--
1997
7
Montana mule deer
6
1
0
4
13
Montana elk
12
1
0
5
9
Illinois wt deer
9
0
0
1.7
3
Sea otter*
0
3
0
9
*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).
1998
4
Montana elk
4
0
0
10
1
Montana mule deer
1
0
0
10
67
Michigan wt deer
50
16
1
4
10
Minnesota wt deer
9
1
0
4
6
Illinois wt deer
6
0
0
2
  Species with the most distinct cementum annuli, occurring in the most regular pattern are expected to be the most accurately aged. An example of a species with distinct, regular annuli is the Rocky Mountain Elk. Bears have distinct annuli, but the pattern produced in successive years is irregular, complicating cementum aging. Mountain lion have the least distinct annuli of any species with which Matson's is experienced, and are expected to be the least accurately aged. The following groupings reflect expected cementum aging accuracy on the basis of cementum characteristics.
  • High accuracy (95%) = Annuli very distinct, pattern very regular
  • Moderate (80-90%) = Annuli and pattern somewhat distinct and regular
  • Low (70-75%) = Annuli indistinct, pattern irregular
High accuracy Moderate Low
Badger *Bear Mountain lion
Fisher .Bison Sea otter
Fox *Black-tailed deer
Goat *Bobcat
Lynx .Caribou
.Coyote
*Elk
.Marten
.Mink
.Moose
*Mule deer
.Muskox
.Pronghorn
.Raccoon
.River otter
.Sheep
.Skunk
.Weasel
*White-tailed deer
.Wolf
.Wolverine
*Populations are variable, some having cementum annulus characteristics expected to yield high accuracy (e.g. Rocky Mountain Elk, northern deer populations) and others to yield moderate accuracy (southern and game farm fed whitetail deer, southwestern mule deer, coastal elk).
Note: Supplementally fed animals have cementum annuli that are characteristically more complex and irregular than wild populations. These characteristics may lower the reliability of age analysis. See additional information in the Accuracy section of Private Hunter, Outfitter, Hunting Club, & Game Farm Clients.

To encourage continuing precision evaluation, Matson's encourages biologists to send "blind" duplicates (paired teeth from the same animal processed without the pairs being identified until after aging). We will process a number of blind duplicates up to 10% of the total sample size, not to exceed 50 teeth. For example, in a sample of 100 teeth 10 blind duplicates would be processed without charge. The resulting precision will be shared on this site and in other publications of the lab. We continue to collect precision data but have not comprehensively tabuated them 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. Clearly, however, results that agree for a pair are not proof of correctness. Results of precision tests with blind duplicates follow (note, from the groupings given above, that accuracy for these species is expected to be moderate or low because of cementum characteristics).

Years
Species
n
Agree
+-1
+-1+
1991-95 Various
414
196
149
67
1995-96 Mt lion
72
37
25
10
1996 Mt lion
6
6
0
0
1996 Wolf
32
21
10
1
1996 Caribou
14
7
6
1
1997 Black bear
4
4
0
0
1997 Moose
11
7
2
2
1997 Mt lion
13
7
3
3
1998 Marten PM1
95
64
25
6
1998 Moose
51
36
8
6
1998 Grizzly
24
20
2
2
1998 WT deer
18
12
4
2
1998 Wolf
6
5
1
0
1998 Caribou
7
6
1
0
All -
767
428
236
100-
Precision of Matson’s Lab Age Analysis Technicians Technicians with more than a year’s experience at our lab can have an opportunity to participate in our in-house training program for age analysis. Species technicians may age are: Black bear, brown bear, elk, whitetail deer, mule deer, raccoon, bobcat, fisher, and marten. Gary Matson checks 10% of all samples aged by technicians. See  "Precision of Matson's Lab Age Analysis Technicians" (PDF). GENERAL CEMENTUM AGE ACCURACY/PRECISION STATEMENT 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 cited above indicates that most species should be aged with an accuracy of 70%, and 90% within 1 year of the correct age. For species with accuracy expected to be low because of indistinct annuli and/or irregular pattern of annulus deposition, 50% should be aged correctly and 85% within 1 year of the correct age.

HelldinRecordFox             From J-O Helldin; Swedish red fox; aged 3-10-04 as 16A (15-17) PronghornTypical5ALRed No. 164, cementum age 17A  Age report filename AH040705-547   Matson’s Lab recently processed and analyzed a North Dakota pronghorn tooth that is the oldest aged in this laboratory. The age of 17 years eclipsed the prior record of 15 years set by an Oregon pronghorn tooth and equaled by one from New Mexico. Most pronghorn harvested are younger than 5 years (photo at left). The record tooth on the right has a thick cementum layer, and not all the annuli are visible in the photo. The first annulus indicates the age of 2 years, because the tooth erupts at the age of 1. The first annulus is formed during the second winter of life. There are 16 annuli in the record tooth. From Jesse Kolar; North Dakota pronghorn; aged 4-7-05 as 17A (photo at right)