Female Ungulate Harvest/Removal Management • Not every animal, either adult or juvenile, lives for ever; hard concept for many people to appreciate • Carrying Capacity – ability of the habitat and distribution of resources to support a certain population level • Harvest/Removal management strategies – – What is the population goal? Social and/or ecological carrying capacity – Where is the population in relation to the goal or population objective? – What rate of removal will meet the goal?
Transcript
Female Ungulate Harvest/Removal Management
• Not every animal, either adult or juvenile, lives for ever; hard concept for many people to appreciate
• Carrying Capacity – ability of the habitat and distribution of resources to support a certain population level
• Harvest/Removal management strategies –– What is the population goal? Social and/or ecological
carrying capacity– Where is the population in relation to the goal or
population objective?– What rate of removal will meet the goal?
Female Ungulate Harvest/Removal Management
– Monitor the population response to removal– Compensatory vs. Additive Mortality– Density Dependent Reproduction– Make annual adjustments to removal rates
• Run through real examples of current elk, pronghorn, and bighorn herds
Elk Herds
19821984
19861988
19901992
19941996
19982000
20022004
20062008
2010-20%
-10%
0%
10%
20%
30%
40%
0
100
200
300
400
500
600
700
800
Elk Herd Parameters for Unit Group 161 - 164
Rate of Increase %Cow Harvest of Total Cow Elk Population Estimate
Perc
ent P
opul
ation
Cha
nge
& C
ow E
lk H
arve
st
Popu
latio
n Es
timat
e
19901991
19921993
19941995
19961997
19981999
20002001
20022003
20042005
20062007
20082009
20102011
-15%
-10%
-5%
0%
5%
10%
15%
20%
0
1000
2000
3000
4000
5000
6000
Elk Herd Parameters for Unit Group 111-115, 221, 222
Rate of Increase %Cow Harvest of Total Cow Elk Population Estimate
Perc
ent P
opul
ation
Cha
nge
& C
ow E
lk H
arve
st
Popu
latio
n Es
timat
e
19931994
19951996
19971998
19992000
20012002
20032004
20052006
20072008
20092010
2011-20%
-15%
-10%
-5%
0%
5%
10%
15%
20%
25%
30%
0
200
400
600
800
1000
1200
1400
1600
1800
Elk Herd Parameters for Unit Group 072, 074
Rate of Increase %Cow Harvest of Total Cow Elk Population Estimate
Perc
ent P
opul
ation
Cha
nge
& C
ow E
lk H
arve
st
Popu
latio
n Es
timat
e
Pronghorn Herds
19961997
19981999
20002001
20022003
20042005
20062007
20082009
20102011
-10%
-5%
0%
5%
10%
15%
20%
0
500
1000
1500
2000
2500
3000
3500
Rate of Increase Population Estimate
Perc
ent P
opul
ation
Cha
nge
& D
oe H
arve
st
Herd
Pop
ulati
on E
stim
ate
19961997
19981999
20002001
20022003
20042005
20062007
20082009
20102011
-20%
-15%
-10%
-5%
0%
5%
10%
15%
0
500
1000
1500
2000
2500
3000
3500
4000
Rate of Increase Population Estimate
Perc
ent P
opul
ation
Cha
nge
& D
oe H
arve
st
Herd
Pop
ulati
on E
stim
ate
19961997
19981999
20002001
20022003
20042005
20062007
20082009
20102011
-10%
-5%
0%
5%
10%
15%
20%
0
500
1000
1500
2000
2500
3000
3500
Pronghorn Herd Parameters for Unit Group 032,034,035 with Doe Harvest
Rate of Increase %Doe Harvest of Total Doe Pronghorn Population Estimate
Pronghorn Herd Parameters for Unit Group 101-104,108,109,144
Rate of Increase Population Estimate
Perc
ent P
opul
ation
Cha
nge
& D
oe H
arve
st
Herd
Pop
ulati
on E
stim
ate
Bighorn Herds
• River Mountains - Desert Bighorn Sheep– 1986 – 240 population estimate– From 1986 – 2010 removed 436 bighorn – 2011 – 250 population estimate
• Mt Jefferson – Desert Bighorn Sheep– 2003 – 290 population estimate– From 2003 – 2008 removed 116 bighorn – 2010 – 280 population estimate
Concept of Compensatory Mortality
in Nevada Pronghorn Herds
Definitions
Compensatory Mortality – • improved survival of remaining animals not
harvested or they are “compensating” for the loss of animals to harvest
Additive Mortality – • no improvement in survival of animals that
were not harvested, therefore loss of harvested animals is in “addition” to animals that die to nonharvest mortality factors
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
0.78
0.8
0.82
0.84
0.86
0.88
0.9
0.92
0.94
0.96
0.98
Comparison of Doe Pronghorn Survival Rates
067, 068 041, 042
YEAR
Annu
al S
urvi
val R
ate
0.600000000000001
0.650000000000001
0.700000000000001
0.750000000000001
0.800000000000001
0.850000000000001
0.900000000000001
0.950000000000001
1Comparison of Doe Pronghorn Survival Rates
032, 034, 035 012 - 014
YEAR
Annu
al S
urvi
val R
ate
Actual Data from Unit 067, 068 Pronghorn Herd subject to
Doe Pronghorn Harvest
Female Pronghorn Age Classes One+
1 2 3 4 5 6 7 8 9 10 does
129 86 95 60 95 51 67 72 52 28 734 Aug 2005
-5 -3 -4 -2 -4 -2 -3 -3 -2 -1 -29 Harvest
-2 -1 -1 -1 -1 -1 -1 -1 -1 0 -9 Wounding Loss
-4 -2 -3 -2 -3 -1 -2 -2 -1 -1 -21Nonhunting
Mortality
119 79 87 55 87 47 61 66 48 25 675survived to
Feb 2006
-4 -4 -2 -3 -2 -3 -1 -2 -2 -1 -23Nonhunting
Mortality
133 115 76 84 53 84 46 60 64 47 762 Aug 2006
Female Pronghorn Age Classes
One+
1 2 3 4 5 6 7 8 9 10 does
129 86 95 60 95 51 67 72 52 28 734 Aug 2005
-6 -4 -5 -3 -5 -3 -3 -4 -3 -1 -37Nonhunting
Mortality
123 81 90 57 90 49 64 68 50 26 697 Survived to Feb
-7 -6 -4 -4 -3 -4 -2 -3 -3 -2 -34Nonhunting
Mortality
135 117 77 85 54 85 46 60 65 47 772 Aug 2006
Same Unit 067, 068 Pronghorn Herd without Harvest
133 115 76 84 53 84 46 60 64 47 762 Aug 2006
Age Class #s with Harvest and Compensatory Mortality
Doe Pronghorn harvest Management
• Statewide Pronghorn estimate for 2011 was 27,000.• Several pronghorn herds statewide are at or approaching
their current carrying capacity. • Other herds are one catastrophic fire away from losing a
significant proportion of their habitat.• Almost 1,300 doe (horns shorter than ears) tag applicants
in 2011; 5 to 1 draw odds; tremendous demand from hunters.
• By applying a 3-5% harvest rate to the doe segment of these herds, we can better manage herds to their habitat, reduce major declines when catastrophic events occur and provide substantial hunting opportunities where expressed demand exists.
