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, 2013 the count of teeth aged in our laboratory was 1,996,542 broken down by species as follows:

Species
Jan 1978 thru Sept 2013
Oldest (yr) to Current Date
From
Badger
1,482
19
Washington
Bear, black
564,834
35
Idaho
Bear, Brown (Grizzly)
56,630
39
Alaska
Bison
3,673
22
N Territories
Boar, wild
56
11
Spain
Bobcat
181,084
23
New Mexico
Caribou
42,776
22
Alaska
Coyote
18,819
15
Colorado
Deer, black-tailed
42,337
22
Oregon
Deer, mule
108,632
20
Washington
Deer, roe
1,879
15
Belgium
Deer, sika
4,368
18
Japan
Deer, white-tailed
230,652
22
Louisiana
Elk
161,190
32
Pennsylvania
Deer, red
3,258
20
Spain
Fisher
14,502
9
-Manitoba
Fox
22,749
-
-
Fox, gray
-
13
California
Fox, red
-
16
Sweden
Fox, silver
-
10
Labrador
Goat, mountain
20,680
18
British Columbia
Lion, mountain
51,481
22
Montana
Lynx
15,889
18
Switzerland
Marten
63,584
16
Alaska
Mink
13,512
10
France
Moose
129,571
22
New Brunswick
Muskox
1026
17
N Territories
Otter, river
34,552
19
Connecticut
Otter, sea
16,202
20
Alaska
Pronghorn
14,888
17
North Dakota
Raccoon
123,954
19
Maryland
Seal
8,910
42
Ontario
Sheep, mountain
3,064
17
British Columbia
Skunk, striped
5,268
12
West Virginia
Weasel, stoat
788
7
New Zealand
Wolf
7,448
15
N Territories
Wolverine
4,906
13
N Territories
Other species
20,935
-
-
TOTAL
1,996,542

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)