Field Identification of Yearling Black Bears Andrew S' Bridges Daniel Lee Michael R' Vaughan

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Field Identification of Yearling Black Bears
Andrew S. BridgesDaniel LeeMichael R. Vaughan
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Cooperative Alleghany Bear Study
3
Cooperative Alleghany Bear Study

• Initiated in 1994 by Virginia Tech and VDGIF to
  examine the population ecology of Virginias
  exploited black bear population

4
Cooperative Alleghany Bear Study

• Initiated in 1994 by Virginia Tech and VDGIF to
  examine the population ecology of Virginias
  exploited black bear population
• 2,500 handlings of 1,500 animals

5
Cooperative Alleghany Bear Study

• Initiated in 1994 by Virginia Tech and VDGIF to
  examine the population ecology of Virginias
  exploited black bear population
• 2,500 handlings of 1,500 animals
• Will conclude in April of this year

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Miscalculations
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Why dont we know more about yearlings?
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Can we get an adequate sample from dens?
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Unfortunately, no
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Summer Captures

• Large trapping effort
• 200-300 handlings of 150-200 individuals per year
• Hunted population so age structure skewed low
• Should be sufficient?

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continued
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Most of our yearlings lt100lbs (45.4 kg)
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Well transmitter anything lt100 lbs!
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It workedbut

• Misidentification in the field resulted in too
  many missed yearlings and too many transmittered
  non-targets

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How can we and future studies be more efficient
and effective?
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Summer Trapping

• Trapped late May-August
• Snares and culverts
• Sedated with ketamine-xylazine
• Took morphological measurements and biological
  samples

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Morphology
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Key
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Variable Selection

• Measurements representing soft tissue and mass,
  skeletal, and sexual development

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Variable Selection

• Measurements representing soft tissue and mass,
  skeletal, and sexual development
• Least ambiguous measures (calipers and scales)

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Variable Selection

• Measurements representing soft tissue and mass,
  skeletal, and sexual development
• Least ambiguous measures (calipers and scales)
• Relative separation

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Relative Separation
(25.0-21.2) ((20.625.5)/2)
0.16
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So how bad were we?

• Misidentified
• 61 yearlings as gt2-years-old
• 2 yearlings as cubs
• 63 gt2-year-olds as yearling

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So how bad were we?

• Identified correctly
• correctly identified 142 yearlings
• enhanced by handlings of known-age bears

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How did our key work?
 
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79-86mm Testes
32-78mm
22
58
22-29mm Teeth
33
14-21mm
79-86mm Testes
101-150 lbs
85
32-78mm
Males
62
5
27
40-100 lbs
79-86mm Testes
32-78mm
59
22-29mm Teeth
14-21mm
61
79-86mm Testes
32-78mm
100
95
 
26
 
14
19
79-86mm Testes
32-78mm
22
58
22-29mm Teeth
33
14-21mm
79-86mm Testes
101-150 lbs
85
32-78mm
Males
62
5
27
40-100 lbs
79-86mm Testes
32-78mm
59
22-29mm Teeth
60
14-21mm
61
79-86mm Testes
32-78mm
100
95
 
27
 
14
19
79-86mm Testes
32-78mm
22
58
22-29mm Teeth
33
14-21mm
79-86mm Testes
101-150 lbs
85
32-78mm
Males
62
5
27
40-100 lbs
79-86mm Testes
32-78mm
59
22-29mm Teeth
60
14-21mm
61
79-86mm Testes
32-78mm
100
95
 
28
 
14
19
79-86mm Testes
32-78mm
22
58
22-29mm Teeth
33
14-21mm
79-86mm Testes
101-150 lbs
85
32-78mm
Males
62
5
27
40-100 lbs
79-86mm Testes
32-78mm
59
22-29mm Teeth
60
14-21mm
61
79-86mm Testes
32-78mm
100
95
 
29
 
14
19
79-86mm Testes
32-78mm
22
58
22-29mm Teeth
33
14-21mm
79-86mm Testes
101-150 lbs
85
32-78mm
62
Males
5
27
40-100 lbs
79-86mm Testes
32-78mm
59
22-29mm Teeth
60
14-21mm
61
79-86mm Testes
32-78mm
100
95
 
30
 
14
19
79-86mm Testes
32-78mm
22
58
22-29mm Teeth
33
14-21mm
79-86mm Testes
85
32-78mm
101-150 lbs
Males
62
5
27
40-100 lbs
79-86mm Testes
32-78mm
59
22-29mm Teeth
60
14-21mm
61
79-86mm Testes
32-78mm
100
95
 
31
 
14
19
79-86mm Testes
32-78mm
22
58
22-29mm Teeth
33
14-21mm
79-86mm Testes
101-150 lbs
85
32-78mm
Males
62
5
27
40-100 lbs
79-86mm Testes
32-78mm
59
22-29mm Teeth
60
14-21mm
61
79-86mm Testes
32-78mm
100
95
 
32
 
14
19
79-86mm Testes
32-78mm
22
58
22-29mm Teeth
33
14-21mm
79-86mm Testes
101-150 lbs
85
32-78mm
Males
62
5
27
40-100 lbs
79-86mm Testes
32-78mm
59
22-29mm Teeth
60
14-21mm
61
79-86mm Testes
32-78mm
100
95
 
33
 
14
19
79-86mm Testes
32-78mm
22
58
22-29mm Teeth
33
14-21mm
79-86mm Testes
101-150 lbs
85
32-78mm
Males
62
5
27
40-100 lbs
79-86mm Testes
32-78mm
59
22-29mm Teeth
60
14-21mm
61
79-86mm Testes
32-78mm
100
95
 
34
 
14
19
79-86mm Testes
32-78mm
22
58
22-29mm Teeth
33
14-21mm
79-86mm Testes
101-150 lbs
85
32-78mm
5
Males
62
27
40-100 lbs
79-86mm Testes
32-78mm
59
22-29mm Teeth
60
14-21mm
61
79-86mm Testes
32-78mm
100
95
 
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Key Evaluation

• Worked well for males
• Not quite as well for females
• Should work for other populations and species
  after recalibration

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Future directions

• More research on yearling ecology
• Tooth replacement

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Acknowledgements

• VDGIF
• Virginia Tech
• USGS
• U.S. Forest Service

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Questions?