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

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

16. Food Resources

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

18. 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

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

20. 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

21. 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

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

23. 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

24. 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)

25. 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”

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

27. Mean Snow Depth

28. Coyote Behavioral Time Budgets Before and After Reintroduction

29. Coyote Behavioral Time Budgets

30. Coyote Behavioral Time Budgets

31. Coyote Behavioral Time Budgets

32. Coyote Behavioral Time Budgets

33. Coyote Behavioral Time Budgets

34. Coyote Behavioral Time Budgets

35. Different Levels of Wolf Activity

36. Presence and Absence of Wolves

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

38. 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

39. 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

40. 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

41. 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

42. 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

43. 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

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

45. Numeric Response to Reintroductions

46. 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

47. 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

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

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

50. 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