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Robert R. Parmenter, Lucina Hernandez, and John Laundre

“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,

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Robert R. Parmenter, Lucina Hernandez, and John Laundre

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  1. “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

  2. 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

  3. 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)

  4. 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.

  5. 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002

  6. 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002

  7. Mean Summer Density

  8. Mean Summer Density Mean Fall/Winter Density

  9. Coyote Energy Budget

  10. Daily Coyote Energy Estimates(adapted from Laundre & Hernandez, [ms. submitted 2002]) ComponentMaleFemale • Body Mass: 11.4 kg9.4 kg • BMR+AMR Requirement: 1,112 kcal922 kcal • Reproduction – Gestation (60 days): 86 kcal • Reproduction – Lactation (30 days): 1,441 kcal • Extra pup food (60 days): 541 kcal541 kcal Total Annual Energy Demand: 438,340 417,380 kcal/yr kcal/yr

  11. Annual Coyote Prey Requirements Prey Species MaleFemale Lepus californicus207199 Neotoma spp. 1,3621,309 Dipodomys spectabilis 2,8482,737 Dipodomys ordii 5,6975,474 Dipodomys merriami 6,9626,690 Peromyscus/Onychomys spp. 14,24213,685 Reithrodontomys spp. 20,88820,071 Perognathus flavus 28,48327,370

  12. 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

  13. 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001

  14. 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002

  15. Daily Summer Coyote Prey Requirements(shown on a per sq. km basis) Daily # Mean # # Days for Prey Species Required Available Depletion L. californicus 0.18 19 106 Neotoma spp. 1.11 7 7 D. spectabilis 2.29 86 38 D. ordii 4.61 115 25 D. merriami 5.64 6 1 Perom./Ony. spp. 11.55 31 3 Reithro. spp. 16.91 2 1 Perog. flavus 23.07 424 19

  16. Daily Fall/Wtr Coyote Prey Requirements(shown on a per sq. km basis) Daily # Mean # # Days for Prey Species Required Available Depletion L. californicus 0.79 19 24 Neotoma spp. 4.86 7 2 D. spectabilis 9.97 86 9 D. ordii 20.08 115 6 D. merriami 24.54 6 1 Perom./Ony. spp. 50.27 31 1 Reithro. spp. 73.63 2 1 Perog. flavus 100.40 424 5

  17. 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001

  18. 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

  19. 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001

  20. 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001

  21. 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

  22. Available = Observed + Est. Reprod. 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

  23. 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. 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

  24. 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

  25. Availability = Observed + Estimated Reproduction 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

  26. Availability = Observed + Estimated Reproduction Reproduction: 1 litter/6 months, which doubles population. 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

  27. 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)

  28. 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.

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