FORAGING ECOLOGY, VIGILANCE OF COYOTES, AND “BEHAVIORAL CASCADES” IN RESPONSE TO GRAY WOLF REINTRODUCTION IN YELLOWST - PowerPoint PPT Presentation

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FORAGING ECOLOGY, VIGILANCE OF COYOTES, AND “BEHAVIORAL CASCADES” IN RESPONSE TO GRAY WOLF REINTRODUCTION IN YELLOWST PowerPoint Presentation
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FORAGING ECOLOGY, VIGILANCE OF COYOTES, AND “BEHAVIORAL CASCADES” IN RESPONSE TO GRAY WOLF REINTRODUCTION IN YELLOWST

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FORAGING ECOLOGY, VIGILANCE OF COYOTES, AND “BEHAVIORAL CASCADES” IN RESPONSE TO GRAY WOLF REINTRODUCTION IN YELLOWST
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FORAGING ECOLOGY, VIGILANCE OF COYOTES, AND “BEHAVIORAL CASCADES” IN RESPONSE TO GRAY WOLF REINTRODUCTION IN YELLOWST

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  1. FORAGING ECOLOGY, VIGILANCE OF COYOTES, AND “BEHAVIORAL CASCADES” IN RESPONSE TO GRAY WOLF REINTRODUCTION IN YELLOWSTONE NATIONAL PARK T. Adam Switalski Post-Project Seminar December 11, 2001

  2. Introduction • Species loss: • Carnivores particularly at risk: • Inherent rarity • Large habitat requirements • Competition with humans

  3. Introduction • Extirpation of Keystone Predators leads to: • Disturbed unstable systems • Increased numbers of prey and competing carnivores • Expanded range • Loss of anti-predatory behaviors • Vigilance • Avoidance • Ultimately, cascading effects

  4. Wolf Range: Past, Present, and Future

  5. Introduction • Case study: reintroduction of wolves in Yellowstone National Park • How are coyotes learning to coexist with wolves? • How are other species responding numerically and behaviorally? • What are the cascading effects?

  6. Foraging Ecology and Vigilance of Coyotes in Response to Wolf Reintroduction • Introduction • Study area • Methods • Results • Discussion

  7. Coyote and Wolf Coexistence • No coexistence • Resource partitioning • Spatial avoidance • Temporal separation • Low degree of diet overlap • Different habitat use

  8. Return of the Wolf to YNP • Historical coexistence • 1995, wolves translocated from Canada • Designated “nonessential experimental” population • Population increased quickly with highest fecundity recorded for species

  9. Foraging Ecology and Vigilance: Research Questions

  10. Foraging Ecology and Vigilance: Research Questions • Do coyotes exhibit different behavioral time budgets now as compared to before wolves were reintroduced into YNP?

  11. Foraging Ecology and Vigilance:Research Questions • Do coyotes exhibit different behavioral time budgets now as compared to before wolves were reintroduced into YNP? • Do coyotes living between wolf packs (‘buffer zones’) exhibit different behavioral time budgets than coyotes in high wolf use areas?

  12. Foraging Ecology and Vigilance: Research Questions • Now that wolves have become established in the Lamar Valley, do coyotes exhibit different behavioral time budgets when wolves are physically present as opposed to their absence?

  13. Study Area: Lamar Valley

  14. Food Resources

  15. Methods • Observations of coyotes and wolves from winter 1998 to summer 2000

  16. Methods • Recorded: • Wolf and coyote location • Type of behavior and time of day • Travel route • Location of behavior • Sex • Social status • Age class • Pack • Pack size

  17. Coyote Behaviors • Rest (alert, sleep) • Travel • Hunting small mammals • Feeding on carcass • Vigilance • Howling • Other

  18. Small Mammal Surveys • Captured during summer 1999 and 2000 • 3 different sites for 2 sessions each year • Mini-grids trapped for 4 days 5 nights and checked twice daily • Once identified, the small mammals were: • Toenail clipped • Weighed • Sexed • Released

  19. Statistics • SAS • Factorial (split-plot) design • Analysis of variance using PROC MIXED • Snow depth was repeated measure • Sample unit was the individual coyote • Proportion of time • Each observation was given equal weight

  20. Statistics • Variables analyzed included: • Wolf activity • Wolf presence • Sex • Year

  21. Results • From December 1997 to July 2000 we made: • 1243 observations of coyotes • 1743 h of coyote activity budgets • 28 resident coyotes from 9 packs • 16 male and 12 females • 24 alphas and 4 betas

  22. Lamar Valley Coyotes • For 60 years, coyotes thrived without wolves • Coyote population reduced 25 to 33% each winter • 23 observed coyote mortalities • Average pack size 3.2 (range = 2.7-3.7) • Very low recruitment (predation and parvo)

  23. Lamar Valley Wolves • Druid Peak and Rose Creek packs introduced into Lamar Valley in 1995 and 1996 • Pack sizes: • 7-8 adults in Druid Peak • 15-22 adults in Rose Creek • Druid Peak pack denned within study area • Wolf territories overlapped creating “buffer zone”

  24. Coyote and Wolf Pack Territories Including Wolf “Buffer Zone”

  25. Mean Snow Depth

  26. Coyote Behavioral Time Budgets Before and After Reintroduction

  27. Coyote Behavioral Time Budgets

  28. Coyote Behavioral Time Budgets

  29. Coyote Behavioral Time Budgets

  30. Coyote Behavioral Time Budgets

  31. Coyote Behavioral Time Budgets

  32. Coyote Behavioral Time Budgets

  33. Different Levels of Wolf Activity

  34. Presence and Absence of Wolves

  35. Discussion • In response to wolf reintroduction coyotes have adjusted their behavior: • Spatially (buffer zone vs. non-buffer zone) • Temporally (present vs. absent)

  36. How has coyote behavior changed? • Increase in the amount of time feeding on carcasses • Consistent with wolf recolonization in NW Montana (Arjo and Pletscher 1999) • Feeding on carcasses throughout the year • Contrasts Gese et al. (1996) • Decrease in travel

  37. Energetic Benefits • Wild coyotes need 930 g of food daily (Bekoff and Wells 1986) • Coyote must consume the equivalent of: • 27 mice • 11 microtines • 6 pocket gophers • 4 ground squirrels • or • Risking a few minutes feeding on a wolf-killed carcass

  38. How is behavior different in the “buffer zone?” • Wolf buffer zones: • Higher deer survivorship • Refuge for coyotes • In YNP, coyotes between Rose Creek and Druid Peak wolf packs have: • Fewer agonistic interactions • Lower mortality rates • Different behaviors

  39. How is behavior different in the “buffer zone?” • Coyote behavior in the buffer zone: • Fed on carcasses less • Little wolf-killed carrion available • Rested more • Vigilant less • Less wary of predation by wolves

  40. Is Behavior Different Wolf Presence? • When wolves were present: • Fed on carcasses more • Wolf-killed carrion almost always present • Rested less • Vigilant more • More wary of predation by wolves • Most coyotes were killed while scavenging wolf kills

  41. Coyote Behavior - Conclusion • Coyote population reduced • Surviving coyotes adjusted behavior • Coyotes benefit from wolf-killed carcasses • Increased feeding on carcasses • Increased costs: • Increased vigilance • Decreased rest • Higher predation risk • Impact varies spatially and temporally

  42. What is the big picture? • Reintroduction of large carnivores leads to: • Numeric response • Behavioral response • Cascading effects

  43. Numeric Response to Reintroductions

  44. Numeric Response to Reintroductions • Contrary results in prey species • In NW MT, elk and deer populations decreased • No prey reduction in YNP, MN, and WI • Reduction of competing carnivores • Coyote population reduced in NW MT and YNP

  45. Behavioral Response to Reintroduction • Minimize encounters • Adjust spatial and/or temporal use: • Elk in National Elk Refuge dispersed • Coyotes in NW MT avoided wolves • Decrease success of attacking predator • Increased vigilance

  46. Vigilance • Aids in: • Detection of predators • Observation of conspecifics • Food acquisition • Prevention of kleptoparasitism

  47. Environmental and Social Variables • Group size • Distance to refuge • Position in the herd • Body size • Age • Parenthood • Habitat type • Predation pressure • Ecotourism

  48. Vigilance Conclusions • Increased risk of predation results in increase in vigilance • Increase in vigilance increases the animals safety, however decreases foraging • In GYE since wolf reintroduction: • Elk, moose, and coyotes have increased their vigilance