The Ecology of FEAR

1. The Ecology of FEAR

3. Fear in the South African Landscape – Augrabies NP Rock Hyrax

4. The view away from the Kopje -

5. Comparison of the lethal and fear approaches Lethal Fear • predators kill their prey • N (population size) - driven systems • Brownian motion behavior of pred/prey • predators scare their prey • - driven systems: fierce predators and • fearful prey • Sophisticated game of stealth and fear L W W L W W L W

6. The Catch-22 of the lethal approach Inefficient predators lead to extinction of the predator in variable environments Efficient predators lead to highly unstable predator- prey interactions K

7. Incorporating the Ecology of Fear (Brown et al. 1999) Prey are apprehensive – i.e., they engage in vigilance behavior M Fear (i.e., predation risk) = ---------------- (prey have perfect info) (k + bu*) Fear: -  w/likelihood of encountering a predator, M -  w/predator’s lethality, 1/k -  w/effectiveness of vigilance, b -  w/level of vigilance, u* # pred, #prey, feeding opportunities

8. Tradeoff: Too much vigilance  miss out on valuable feeding opportunities Too little vigilance  likely killed by a predator • bend down the predator’s • isocline. • Predator’s have reduced • efficiency because more • predators results in greater • vigilance in the prey making • them harder to catch • Interference or Behavioral Resource Depression Shift the hump in the prey’s isocline. Still safety in #s, but reduced vigilance reduces effectiveness K K*

9. Implications: • Greater stability in predator-prey interactions – no Catch-22, • Predator regulation is not tied to the number of prey killed • (3) Territoriality in fierce predators may function to protect the • catchability of the prey – avoid the “wayward” Mnt. Lion • stumbling into your territory • (4) Behavior (e.g., vigilance) is a leading indicator of ecological • change

10. Wolves, elk, and bison in Yellowstone: reestablishing the “Landscape of Fear” (Laundre et al. 2001 – Can J. Zool. 79:1401) Wolves reintroduced into the Lamar Valley of Yellowstone in 1994-1995.

11. This now becomes a familiar scene – wohoo!!!

12. Vigilance in female elk w/calves increases… ...while time spent foraging declines

13. Similarly for bison, however, males and females w/o calves no show behavioral shift

14. 1996 2002

15. 1997 versus 2001

16. Three kinds of evidence: • The changes are much faster • than could occur from elk • mortality • Reduced herbivory is restricted • to risky habitats • Elk have exhibited behavioral • changes consistent with an • Ecology of Fear Hypothesis: • (1) avoid forest edge (scat) • (2) increased vigilance and • less feeding • These changes have left • physiological evidence

17. Cottonwood trees need wolves in order to establish their populations.... ...as does willow and aspen.

18. Predation Risk So what other responses are there?

19. Red Knot Calidris canutus Tidal mudflat foragers

20. Ruddy turnstone Arenaria interpres Inshore foragers

21. Differences in predator escape? • Knots – advanced warning and collective flight maneuvers • Turnstones – little warning, find cover, every turnstone for itself

23. At the Netherlands Institute for Sea Research the animal caretaker kept track of knots’ abilities to make 90 degree turns into the aviary….. > 160 g, knots compromise their flight abilities

24. Flight performance increases with an increase in the ratio of: Pectoral Muscle Mass/Body Mass So how do you increase flight performance?

25. Body Building to defy death

26. Red-eyed tree frog Agalychnis callidryas

27. What’s the tradeoff?

28. Early hatchers Late hatchers

29. Snakes Wind Rain

30. http://people.bu.edu/kwarken/KWvideo.html