robert r. parmenter, lucina hernandez, and john laundre
DESCRIPTION
“Top Down” predator controls of ecosystem processes: Can coyotes ( Canis latrans ) dampen prey population cycles and influence herbivory rates on the Sevilleta NWR?. Robert R. Parmenter, Lucina Hernandez, and John Laundre Department of Biology, University of New Mexico, - PowerPoint PPT PresentationTRANSCRIPT
“Top Down” predator controls of ecosystem processes:
Can coyotes (Canis latrans) dampen prey population cycles and influence herbivory
rates on the Sevilleta NWR?
Robert R. Parmenter, Lucina Hernandez, and John Laundre
Department of Biology, University of New Mexico,
and Instituto de Ecologia, Durango, Mexico
Estimating coyote impacts on small mammal prey:
• Need coyote density estimates
• Need coyote energy requirements and prey energy equivalences, coupled with digestive assimilation efficiencies
• Need small mammal prey density estimates
• Need coyote diet composition data
• Need estimates of prey productivity
Coyote Density Estimation• Statistics derived from basin-and-range
topographic regions of shrub-steppe in Utah.
• Absolute densities (D=N/A) calculated from 8 coyote populations enumerated during radio-collar studies (i.e., known numbers of coyotes, N, and known home range sizes, A).
• Verified coyote enumeration using radioactive markers in scats.
(Data from Dr. F. F. Knowlton and colleagues, Utah State University)
Development of Scat Index
• Collected coyote scats along measured lengths of dirt roads on valley flats.
• First, cleared roads of scats, then resampled at a later date (several days to a week).
• Scat Index computed as # scats per 24-hour period per mile of road.• Index then correlated with known coyote
density in same area at same time.
Relationship of Coyote Density and Scat Index
Y = 11.42X + 2.66
r2 = 0.97
0.0
5.0
10.0
15.0
20.0
25.0
30.0
35.0
40.0
45.0
50.0
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5
Coyote Density (No./Sq. Mile)
Sca
t Ind
ex (N
o./M
ile-D
ay)X
100
Coyote Densities, SNWR McKenzie Flats
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
W S W S W S W S W S W S W S W S W S W S W S
Sampling Periods, 1992-2002
Dens
ity (N
o./S
q. K
m.)
1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002
Coyote Densities, SNWR McKenzie Flats
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
W S W S W S W S W S W S W S W S W S W S W S
Sampling Periods, 1992-2002
Dens
ity (N
o./S
q. K
m.)
1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002
Relationship of Coyote Density and Scat Index
Y = 11.42X + 2.66
r2 = 0.97
0.0
5.0
10.0
15.0
20.0
25.0
30.0
35.0
40.0
45.0
50.0
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5
Coyote Density (No./Sq. Mile)
Sca
t Ind
ex (N
o./M
ile-D
ay)X
100
Relationship of Coyote Density and Scat Index
Y = 11.42X + 2.66
r2 = 0.97
0.0
5.0
10.0
15.0
20.0
25.0
30.0
35.0
40.0
45.0
50.0
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5
Coyote Density (No./Sq. Mile)
Sca
t Ind
ex (N
o./M
ile-D
ay)X
100 Mean
Summer Density
Relationship of Coyote Density and Scat Index
Y = 11.42X + 2.66
r2 = 0.97
0.0
5.0
10.0
15.0
20.0
25.0
30.0
35.0
40.0
45.0
50.0
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5
Coyote Density (No./Sq. Mile)
Sca
t Ind
ex (N
o./M
ile-D
ay)X
100 Mean
Summer Density
MeanFall/WinterDensity
Coyote Energy Budget
B a sa l M e ta b o lic R a te(a t re s t)
A c tiv ity M e ta b o lic R a te(fo ra g in g , te rrito ry d e fe n se)
R e pro d uc tion(p re gn a n cy, la c ta tio n )
T o ta l E n e rg y D em a nd
Daily Coyote Energy Estimates (adapted from Laundre & Hernandez, [ms. submitted 2002])
Component Male Female
• Body Mass: 11.4 kg 9.4 kg
• BMR+AMR Requirement: 1,112 kcal 922 kcal
• Reproduction – Gestation (60 days): 86 kcal
• Reproduction – Lactation (30 days): 1,441 kcal
• Extra pup food (60 days): 541 kcal 541 kcal
Total Annual Energy Demand: 438,340 417,380
kcal/yr kcal/yr
Annual Coyote Prey RequirementsPrey Species Male Female
Lepus californicus 207 199
Neotoma spp. 1,362 1,309
Dipodomys spectabilis 2,848 2,737
Dipodomys ordii 5,697 5,474
Dipodomys merriami 6,962 6,690
Peromyscus/Onychomys spp. 14,242 13,685
Reithrodontomys spp. 20,888 20,071
Perognathus flavus 28,483 27,370
Daily Coyote Prey Requirements
Prey Species # Required/day
Lepus californicus 0.6
Neotoma spp. 3.7
Dipodomys spectabilis 7.6
Dipodomys ordii 15.3
Dipodomys merriami 18.7
Perom./Onych. spp. 38.3
Reithrodontomys spp. 56.1
Perognathus flavus 76.5
Rodent Densities, 5-Points Grassland
0
500
1000
1500
2000
2500
3000
3500
4000
4500
Den
sity
(No.
/Sq.
Km
.)
Dipodomys spectabilis Dipodomys merriami Dipodomys ordii
Perognathus flavus Neotoma albigula Neotoma micropus
Onychomys arenicola Reithrodontomys megalotis Peromyscus truei
Peromyscus eremicus Peromyscus leucopus Peromyscus boylii
1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001
Rabbit Densities, SNWR McKenzie Flats
0
10
20
30
40
50
60
W S W S W S W S W S W S W S W S W S W S W S
Sampling Periods, 1992-2002
Dens
ity (N
o./S
q. K
m.)
1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002
Daily Summer Coyote Prey Requirements(shown on a per sq. km basis)
Daily # Mean # # Days forPrey Species Required Available Depletion L. californicus 0.18 19 106Neotoma spp. 1.11 7 7D. spectabilis 2.29 86 38D. ordii 4.61 115 25D. merriami 5.64 6 1Perom./Ony. spp. 11.55 31 3Reithro. spp. 16.91 2 1Perog. flavus 23.07 424 19
Daily Fall/Wtr Coyote Prey Requirements(shown on a per sq. km basis)
Daily # Mean # # Days forPrey Species Required Available Depletion L. californicus 0.79 19 24Neotoma spp. 4.86 7 2D. spectabilis 9.97 86 9D. ordii 20.08 115 6D. merriami 24.54 6 1Perom./Ony. spp. 50.27 31 1Reithro. spp. 73.63 2 1Perog. flavus 100.40 424 5
Density (Rodents + Rabbits)
0
1000
2000
3000
4000
Den
sity
(N
o./
Sq
. K
m.)
Dipodomys spectabilis Dipodomys merriamiDipodomys ordii Perognathus flavusNeotoma albigula Neotoma micropusOnychomys arenicola Reithrodontomys megalotisPeromyscus truei Peromyscus eremicusPeromyscus leucopus Peromyscus boyliiLepus californicus
1992 1993 1994 1995 1996 1997 1998 1999 2000 2001
Coyote Diet Composition
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
Die
t C
om
po
siti
on
(%
)
Rabbits Rodents Arthropods Ungulates Birds Reptiles Cattle Other Plants
W S S F W S S F W S S F W S S F W S S F W S S F W S S F W S S F W S S F W S S F W S
1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002
Density (Rodents + Rabbits)
0
1000
2000
3000
4000
Den
sity
(N
o./
Sq
. K
m.)
Dipodomys spectabilis Dipodomys merriamiDipodomys ordii Perognathus flavusNeotoma albigula Neotoma micropusOnychomys arenicola Reithrodontomys megalotisPeromyscus truei Peromyscus eremicusPeromyscus leucopus Peromyscus boyliiLepus californicus
1992 1993 1994 1995 1996 1997 1998 1999 2000 2001
Live Biomass (Rodents + Rabbits)
0
40000
80000
120000
160000
Bio
mas
s (G
ram
s/S
q. K
m.)
Dipodomys spectabilis = 110 g Dipodomys merriami = 45 gDipodomys ordii = 55 g Perognathus flavus = 11 gNeotoma albigula = 215 g Neotoma micropus = 250 gOnychomys arenicola = 25 g Reithrodontomys megalotis = 15gPeromyscus truei = 24 g Peromyscus eremicus = 20 gPeromyscus leucopus = 20 g Peromyscus boylii = 25 gLepus californicus= 2,300 g
1992 1993 1994 1995 1996 1997 1998 1999 2000 2001
Rabbit Productivity Vs. Predation
0
20
40
60
80
100
120
140
160
Den
sity
(No.
/Sq.
Km
.)
No. rabbits eaten per season Total rabbits available
W S S F W S S F W S S F W S S F W S S F W S S F W S S F W S S F W S S F W S S F W S
1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002
Rabbit Productivity Vs. Predation
0
20
40
60
80
100
120
140
160
Den
sity
(No.
/Sq.
Km
.)
No. rabbits eaten per season Total rabbits available
W S S F W S S F W S S F W S S F W S S F W S S F W S S F W S S F W S S F W S S F W S
1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002
Available = Observed + Est. Reprod.
Rabbit Productivity Vs. Predation
0
20
40
60
80
100
120
140
160
Den
sity
(No.
/Sq.
Km
.)
No. rabbits eaten per season Total rabbits available
W S S F W S S F W S S F W S S F W S S F W S S F W S S F W S S F W S S F W S S F W S
1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002
Available = Observed + Est. Reprod.Reproduction: 1 litter/season:F-A: 4.5/litter; M-J: 3/litter; A-O: 2/litter, N-J: 1/litter.
Rodent Productivity Vs. Predation
0
2000
4000
6000
8000
10000
12000
Den
sity
(No.
/Sq.
Km
.)
No. rodents eaten per season Total rodents available
S F S F S F S F S F S F S F S F S F S F
1992 1993 1994 1995 1996 1997 1998 1999 2000 2001
Rodent Productivity Vs. Predation
0
2000
4000
6000
8000
10000
12000
Den
sity
(No.
/Sq.
Km
.)
No. rodents eaten per season Total rodents available
S F S F S F S F S F S F S F S F S F S F
1992 1993 1994 1995 1996 1997 1998 1999 2000 2001
Availability = Observed + Estimated Reproduction
Rodent Productivity Vs. Predation
0
2000
4000
6000
8000
10000
12000
Den
sity
(No.
/Sq.
Km
.)
No. rodents eaten per season Total rodents available
S F S F S F S F S F S F S F S F S F S F
1992 1993 1994 1995 1996 1997 1998 1999 2000 2001
Availability = Observed + Estimated Reproduction
Reproduction: 1 litter/6 months,
which doubles population.
Coyote Impacts on Small Mammals:
• At Sevilleta, potential average reduction of rabbit productivity by 46%
• At Sevilleta, potential average reduction of rodent productivity by 32%
• In west Texas, coyote presence resulted in an average ~50% reduction of rabbits and kangaroo rats compared to coyote removal areas (Henke & Bryant 1999)
Tentative Conclusions
• Coyote predation results in substantial removal of prey biomass, prey densities.
• Coyote predation influences small mammal prey population dynamics, but cannot consistently prevent episodic population outbreaks (associated with precipitation dynamics).
• Experimental coyote manipulations needed to verify these calculations.