Questions of whether trophic cascades occur in Isle Royale National Park (IRNP) or Yellowstone National Park's northern range (NR) cannot lead to simple, precise, or definitive answers. Such answers are limited especially by multicausality in the NR and by complex temporal variation in IRNP. Spatial heterogeneity, contingency, and nonequilibrium dynamics also work against simple answers in IRNP and NR. The existence of a trophic cascade in IRNP and NR also depends greatly on how it is defined. For example, some conceive of trophic cascades as entailing essentially any indirect effect of predation. This may be fine, but the primary intellectual value of such a conception may be to assess an important view in community ecology that most species are connected to most other species in a food web through a network of complicated, albeit weak, indirect effects. These circumstances that work against simple answers likely apply to many ecosystems. Despite the challenges of assessing the existence of trophic cascades in IRNP and NR, such assessments result in considerable insights about a more fundamental question: What causes population abundance to fluctuate?

Keyword(s): ecosystemelkherbivorymoosepredationwolf

Article metrics loading...

Loading full text...

Full text loading...


Literature Cited

  1. Adams JR, Vucetich LM, Hedrick PW, Peterson RO, Vucetich JA. 2011. Genomic sweep and potential genetic rescue during limiting environmental conditions in an isolated wolf population. Proc. R. Soc. B 278:17233336–44 [Google Scholar]
  2. Allen DL. 1954. Our Wildlife Legacy New York: Funk & Wagnalls [Google Scholar]
  3. Barber-Meyer SM, Mech LD, White PJ. 2008. Elk calf survival and mortality following wolf restoration to Yellowstone National Park. Wildl. Monogr. 169:1–30 [Google Scholar]
  4. Bartos DL. 2001. Landscape dynamics of aspen and conifer forests. Sustaining Aspen in Western Landscapes: Symposium Proceedings WD Shepperd, D Binkley, DL Bartos, TJ Stohlgren, LG Eskew 5–14 Fort Collins, CO: USDA For. Serv. [Google Scholar]
  5. Bergman BG, Bump JK. 2014. Experimental evidence that effects of moose and beaver aquatic herbivory may be contingent on water body type. Freshw. Biol. Accepted [Google Scholar]
  6. Beschta RL. 2005. Reduced cottonwood recruitment following extirpation of wolves in Yellowstone's northern range. Ecology 86:2391–403 [Google Scholar]
  7. Beschta RL, Ripple WJ. 2012. The role of large predators in maintaining riparian plant communities and river morphology. Geomorphology 157–58:88–98 [Google Scholar]
  8. Beschta RL, Ripple WJ. 2013. Are wolves saving Yellowstone's aspen? A landscape-level test of a behaviorally mediated trophic cascade: comment. Ecology 94:61420–25 [Google Scholar]
  9. Beschta RL, Ripple WJ. 2014. Divergent patterns of riparian cottonwood recovery after the return of wolves in Yellowstone, USA. Ecohydrology Epub ahead of print; doi: 10.1002/eco.1487 [Google Scholar]
  10. Beyer HL, Merrill EH, Varley N, Boyce MS. 2007. Willow on Yellowstone's northern range: evidence for a trophic cascade?. Ecol. Appl. 17:61563–71 [Google Scholar]
  11. Botkin DB. 2012. The Moon in the Nautilus Shell: Discordant Harmonies Reconsidered New York: Oxford Univ. Press [Google Scholar]
  12. Boyce MS. 1998. Ecological-process management and ungulates: Yellowstone's conservation paradigm. Wildl. Soc. Bull. 26:3391–98 [Google Scholar]
  13. Boyce MS, Gaillard JM. 1992. Wolves in Yellowstone, Jackson Hole, and the North Fork of the Shoshone River: simulating ungulate consequences of wolf recovery. Wolves for Yellowstone? A Report to the United States Congress IV Research and Analysis JD Varley, WG Brewster 4–116 Yellowstone Natl. Park: Natl. Park Serv. [Google Scholar]
  14. Brandner TA, Peterson RO, Risenhoover KL. 1990. Balsam fir on Isle Royale: effects of moose herbivory and population density. Ecology 71:155–64 [Google Scholar]
  15. Brodie J, Post E, Watson F, Berger J. 2012. Climate change intensification of herbivore impacts on tree recruitment. Proc. R. Soc. B 279:17321366–70 [Google Scholar]
  16. Brown K, Hansen AJ, Keane RE, Graumlich LJ. 2006. Complex interactions shaping aspen dynamics in the greater Yellowstone ecosystem. Landsc. Ecol. 21:6933–51 [Google Scholar]
  17. Bump JK, Peterson RO, Vucetich JA. 2009. Wolves modulate soil nutrient heterogeneity and foliar nitrogen by configuring the distribution of ungulate carcasses. Ecology 90:113159–67 [Google Scholar]
  18. Cook RC, Cook JG, Mech LD. 2004. Nutritional condition of northern Yellowstone elk. J. Mammal. 85:4714–22 [Google Scholar]
  19. Creel S, Christianson D, Liley S, Winnie JA. 2007. Predation risk affects reproductive physiology and demography of elk. Science 315:5814960 [Google Scholar]
  20. Creel S, Christianson D, Winnie JA. 2011. A survey of the effects of wolf predation risk on pregnancy rates and calf recruitment in elk. Ecol. Appl. 21:2847–53 [Google Scholar]
  21. Creel S, Winnie JA, Christianson D. 2009. Glucocorticoid stress hormones and the effect of predation risk on elk reproduction. Proc. Natl. Acad. Sci. USA 106:3012388–93 [Google Scholar]
  22. Creel S, Winnie JA, Christianson D. 2013. Underestimating the frequency, strength and cost of antipredator responses with data from GPS collars: an example with wolves and elk. Ecol. Evol. 3:165189–200 [Google Scholar]
  23. DeJager NR, Pastor J. 2009. Declines in moose population density at Isle Royale National Park, MI, USA and accompanied changes in landscape patterns. Landsc. Ecol. 24:101389–403 [Google Scholar]
  24. Eberhardt LL, White PJ, Garrott RA, Houston DB. 2007. A 70-year history of trends in Yellowstone's northern elk herd. J. Wildl. Manag. 71:2594–602 [Google Scholar]
  25. Eisenberg C, Seager ST, Hibbs DE. 2013. Wolf, elk, and aspen food web relationships: context and complexity. For. Ecol. Manag. 299:70–80 [Google Scholar]
  26. Endress BA, Wisdom MJ, Vavra M, Parks CG, Dick BL. et al. 2012. Effects of ungulate herbivory on aspen, cottonwood, and willow development under forest fuels treatment regimes. For. Ecol. Manag. 276:33–40 [Google Scholar]
  27. Evans SB, Mech LD, White PJ, Sargeant GA. 2006. Survival of adult female elk in Yellowstone following wolf restoration. J. Wildl. Manag. 70:51372–78 [Google Scholar]
  28. Frank DA. 2008. Evidence for top predator control of a grazing ecosystem. Oikos 117:111718–24 [Google Scholar]
  29. Frank DA. 2013. Assessing the effects of climate change and wolf restoration on grassland processes. Yellowstone's Wildlife in Transition PJ White, RA Garrott, GE Plumb 195–208 Cambridge, MA: Harvard Univ. Press [Google Scholar]
  30. Frelich LE, Peterson RO, Dovčiak M, Reich PB, Vucetich JA, Eisenhauer N. 2012. Trophic cascades, invasive species and body-size hierarchies interactively modulate climate change responses of ecotonal temperate-boreal forest. Philos. Trans. R. Soc. B 367:16052955–61 [Google Scholar]
  31. Fretwell SD. 1987. Food chain dynamics: the central theory of ecology?. Oikos 50:291–301 [Google Scholar]
  32. Fuller TK, Mech LD, Cochrane JF. 2003. Wolf population dynamics. Wolves: Behavior, Ecology, and Conservation LD Mech, L Boitani 161–91 Chicago, IL: Univ. Chicago Press [Google Scholar]
  33. Gray ST, Graumlich LJ, Betancourt JL. 2007. Annual precipitation in the Yellowstone National Park region since AD 1173. Quat. Res. 68:18–27 [Google Scholar]
  34. Hairston NG, Smith FE, Slobodkin LB. 1960. Community structure, population control, and competition. Am. Nat. 94:421–25 [Google Scholar]
  35. Hamlin KL, Garrott RA, White PJ, Cunningham JA. 2009. Contrasting wolf-ungulate interactions in the greater Yellowstone ecosystem. The Ecology of Large Mammals in Central Yellowstone: Sixteen Years of Integrated Field Studies RA Garrott, PJ White, FGR Watson 541–77 San Diego, CA: Elsevier [Google Scholar]
  36. Hedrick PW, Peterson RO, Vucetich LM, Adams JR, Vucetich JA. 2014. Genetic rescue in Isle Royale wolves: genetic analysis and the collapse of the population. Conserv. Genet. 151111–21 [Google Scholar]
  37. Hessl AE. 2002. Aspen, elk, and fire: the effects of human institutions on ecosystem processes. Bioscience 52:111011–22 [Google Scholar]
  38. Hessl AE, Graumlich LJ. 2002. Interactive effects of human activities, herbivory and fire on quaking aspen (Populus tremuloides) age structures in western Wyoming. J. Biogeogr. 29:7889–902 [Google Scholar]
  39. Hjeljord O, Hövik N, Pedersen HB. 1990. Choice of feeding sites by moose during summer, the influence of forest structure and plant phenology. Ecography 13:4281–92 [Google Scholar]
  40. Houston DB. 1982. The Northern Yellowstone Elk: Ecology and Management New York: MacMillan [Google Scholar]
  41. Huber NK. 1973. Glacial and postglacial geologic history of Isle Royale National Park, Michigan Geol. Surv. Prof. Paper 754-A, US Gov. Print. Off., Washington, DC [Google Scholar]
  42. Hung C-L, Gurarie V, Chin C. 2013. From cosmology to cold atoms: observation of Sakharov oscillations in a quenched atomic superfluid. Science 341:1213–15 [Google Scholar]
  43. Interag. Grizzly Bear Study Team 2013. Response of Yellowstone grizzly bears to changes in food resources: a synthesis. Rep. Interag. Grizzly Bear Comm. Yellowstone Ecosyst. Subcomm., US Geol. Surv., Northern Rocky Mount. Sci. Cent., Bozeman, Mont. [Google Scholar]
  44. Janke RA, McKaig D, Raymond R. 1978. Comparison of presettlement and modern upland boreal forests on Isle Royale National Park. For. Sci. 24:115–21 [Google Scholar]
  45. Jordan PA, McLaren BE, Sell SM. 2000. A summary of research on moose and related ecological topics at Isle Royale, U. S.A. Alces 36:233–67 [Google Scholar]
  46. Kauffman MJ, Brodie JF, Jules ES. 2010. Are wolves saving Yellowstone's aspen? A landscape-level test of a behaviorally mediated trophic cascade. Ecology 91:92742–55 [Google Scholar]
  47. Kauffman MJ, Brodie JF, Jules ES. 2013. Are wolves saving Yellowstone's aspen? A landscape-level test of a behaviorally mediated trophic cascade: reply. Ecology 94:1425–31 [Google Scholar]
  48. Kimble DS, Tyers DB, Robison-Cox J, Sowell BF. 2011. Aspen recovery since wolf reintroduction on the northern Yellowstone winter range. Rangel. Ecol. Manag. 64:2119–30 [Google Scholar]
  49. Kulakowski D, Kaye MW, Kashian DM. 2013. Long-term aspen cover change in the western US. For. Ecol. Manag. 299:52–59 [Google Scholar]
  50. Kulakowski D, Veblen TT, Drinkwater S. 2004. The persistence of quaking aspen (Populus tremuloides) in the Grand Mesa area, Colorado. Ecol. Appl. 14:51603–14 [Google Scholar]
  51. Lemke TO. 2003. Gardiner late elk hunt. Annu. Rep. 2003, Montana Fish Wildl. Parks, Livingston, Mont. [Google Scholar]
  52. Lemke TO, Mack JA, Houston DB. 1998. Winter range expansion by the northern Yellowstone elk herd. Intermount. J. Sci. 4:1/21–9 [Google Scholar]
  53. Lime DW, Koth BA, Vlaming JC. 1993. Effects of restoring wolves on Yellowstone big game and grizzly bears: opinions of scientists. Ecological Issues on Reintroducing Wolves into Yellowstone National Park RS Cook 306–28 Sci. Monogr. NPS/NRYELL/NRSM-93/22 Washington, DC: US Dep. Inter., Natl. Park Serv. [Google Scholar]
  54. Linn RM. 1957. The spruce-fir maple-birch transition in Isle Royale National Park PhD thesis. Duke Univ., Durham [Google Scholar]
  55. Marshall KN, Cooper DJ, Hobbs NT. 2014. Interactions among herbivory, climate, topography, and plant age shape riparian willow dynamics in northern Yellowstone National Park, USA. J. Ecol. 102:3667–77 [Google Scholar]
  56. Marshall KN, Hobbs NT, Cooper DJ. 2013. Stream hydrology limits recovery of riparian ecosystems after wolf reintroduction. Proc. R. Soc. B 280:120122977 [Google Scholar]
  57. McCann KS. 2011. Food Webs Princeton, NJ: Princeton Univ. Press [Google Scholar]
  58. McLaren BE. 1996. Plant-specific response to herbivory: simulated browsing of suppressed balsam fir on Isle Royale. Ecology 77:228–35 [Google Scholar]
  59. McLaren BE, Janke RA. 1996. Seedbed and canopy cover effects on balsam fir seedling establishment in Isle Royale National Park. Can. J. For. Res. 26:5782–93 [Google Scholar]
  60. McLaren BE, Peterson RO. 1994. Wolves, moose, and tree rings on Isle Royale. Science 266:1555–58 [Google Scholar]
  61. Mech LD. 2012. Is science in danger of sanctifying the wolf?. Biol. Conserv. 150:143–49 [Google Scholar]
  62. Metz MC, Smith DW, Vucetich JA, Stahler DR, Peterson RO. 2012. Seasonal patterns of predation for gray wolves in the multi-prey system of Yellowstone National Park. J. Anim. Ecol. 81:3553–63 [Google Scholar]
  63. Middleton AD, Kauffman MJ, McWhirter DE, Cook JG, Cook RC. et al. 2013a. Animal migration amid shifting patterns of phenology and predation: lessons from a Yellowstone elk herd. Ecology 94:61245–56 [Google Scholar]
  64. Middleton AD, Morrison TA, Fortin JK, Robbins CT, Proffitt KM. et al. 2013b. Grizzly bear predation links the loss of native trout to the demography of migratory elk in Yellowstone. Proc. R. Soc. B 280:20130870 [Google Scholar]
  65. Miller JRB, Ament JM, Schmitz OJ. 2013. Fear on the move: predator hunting mode predicts variation in prey mortality and plasticity in prey spatial response. J. Anim. Ecol. 83:214–22 [Google Scholar]
  66. Monbiot G. 2014. How wolves change rivers. Sustainable Man: there are other ways of doing things Feb. 17. http://sustainableman.org/blog/2014/02/17/how-wolves-change-rivers/ [Google Scholar]
  67. Montgomery RA, Vucetich JA, Peterson RO, Roloff GJ, Millenbah KF. 2012. The influence of winter severity, predation and senescence on moose habitat use. J. Anim. Ecol. 82:2301–09 [Google Scholar]
  68. Montgomery RA, Vucetich JA, Peterson RO, Roloff GJ, Millenbah KF. 2014. Where wolves kill moose: the influence of prey life history dynamics on the landscape ecology of predation. PLOS ONE 9:3e91414 [Google Scholar]
  69. Natl. Res. Counc 2002. Ecological Dynamics on Yellowstone's Northern Range. Washington, DC: Natl. Acad. Press [Google Scholar]
  70. Oksanen L, Fretwell SD, Arruda J, Niemela P. 1981. Exploitation ecosystems in gradients of primary productivity. Am. Nat. 118:240–61 [Google Scholar]
  71. Pace ML, Cole JJ, Carpenter SR, Kitchell JF. 1999. Trophic cascades revealed in diverse ecosystems. Trends Ecol. Evol. 14:12483–88 [Google Scholar]
  72. Painter LE. 2013. Trophic cascades and large mammals in the Yellowstone ecosystem PhD thesis. Fish. Wildl. Dep., Or. State Univ., Corvallis [Google Scholar]
  73. Pastor J, Dewey B, Naiman RJ, McInnes PF, Cohen Y. 1993. Moose browsing and soil fertility in the boreal forests of Isle Royale National Park. Ecology 74:2467–80 [Google Scholar]
  74. Peterson RO. 1977. Wolf ecology and prey relationships on Isle Royale Natl. Park Serv. Sci. Monogr. Ser. 11 Washington, DC: Natl. Park Serv. [Google Scholar]
  75. Peterson RO, Vucetich JA, Page RE, Chouinard A. 2003. Temporal and spatial aspects of predator-prey dynamics. Alces 39:215–32 [Google Scholar]
  76. Peterson RO, Romanski M. 2012. Beaver survey 2010 and summary report for beaver surveys 2006–2010, Isle Royale National Park Isle Royale National Park, Natl. Park Serv., Houghton, MI. [Google Scholar]
  77. Peterson RO, Thomas NJ, Thurber JM, Vucetich JA, Waite TA. 1998. Population limitation and the wolves of Isle Royale. J. Mammal. 79:828–41 [Google Scholar]
  78. Polis GA, Sears ALW, Huxel GR, Strong DR, Maron J. 2000. When is a trophic cascade a trophic cascade?. Trends Ecol. Evol. 15:11473–75 [Google Scholar]
  79. Renaud PC, Verheyden-Tixier H, Dumont B. 2003. Damage to saplings by red deer (Cervus elaphus): effect of foliage height and structure. For. Ecol. Manag. 181:31–37 [Google Scholar]
  80. Ripple WJ, Beschta RL. 2004. Wolves and the ecology of fear: Can predation risk structure ecosystems?. Bioscience 54:8755–66 [Google Scholar]
  81. Ripple WJ, Beschta RL. 2007. Restoring Yellowstone's aspen with wolves. Biol. Conserv. 138:3514–19 [Google Scholar]
  82. Ripple WJ, Beschta RL. 2012. Trophic cascades in Yellowstone: the first 15 years after wolf reintroduction. Biol. Conserv. 145:205–13 [Google Scholar]
  83. Ripple WJ, Beschta RL, Fortin JK, Robbins CT. 2013. Trophic cascades from wolves to grizzly bears in Yellowstone. J. Anim. Ecol. 83:223–33 [Google Scholar]
  84. Ripple WJ, Estes JA, Beschta RL, Wilmers CC, Ritchie EG. et al. 2014. Status and ecological effects of the world's largest carnivores. Science 343:61671241484 [Google Scholar]
  85. Ripple WJ, Larsen EJ, Renkin RA, Smith DW. 2001. Trophic cascades among wolves, elk and aspen on Yellowstone National Park's northern range. Biol. Conserv. 102:3227–34 [Google Scholar]
  86. Ripple WJ, Painter LE, Beschta RL, Gates CC. 2010. Wolves, elk, bison, and secondary trophic cascades in Yellowstone National Park. Open Ecol. J. 3:31–37 [Google Scholar]
  87. Romme WH, Turner MG, Wallace LL, Walker JS. 1995. Aspen, elk, and fire in northern Yellowstone Park. Ecology 76:72097–106 [Google Scholar]
  88. Ruth TK, Buotte PC, Hornocker MG. 2014. Yellowstone Cougars: Ecology Before and During Wolf Reestablishment Boulder: Univ. Press Colo. [Google Scholar]
  89. Ruth TK, Murphy K. 2010. Cougar-prey relationships. Cougar M Hornocker, S Negri 163–74 Chicago, IL: Univ. Chicago Press [Google Scholar]
  90. Sandercock BK, Nilsen EB, Brøseth H, Pedersen HC. 2011. Is hunting mortality additive or compensatory to natural mortality? Effects of experimental harvest on the survival and cause specific mortality of willow ptarmigan. J. Anim. Ecol. 80:244–58 [Google Scholar]
  91. Sankey TT. 2012. Decadal-scale aspen changes: evidence in remote sensing and tree ring data. Appl. Veg. Sci. 15:1 doi: 10.1111/j.1654-109X.2011.01141.x [Google Scholar]
  92. Schmitz OJ. 2004. Perturbation and abrupt shift in trophic control of biodiversity and productivity. Ecol. Lett. 7:5403–9 [Google Scholar]
  93. Schmitz OJ. 2010. Resolving Ecosystem Complexity Princeton, NJ: Princeton Univ. Press [Google Scholar]
  94. Schmitz OJ, Hamback PA, Beckerman AP. 2000. Trophic cascades in terrestrial systems: a review of the effects of carnivore removals on plants. Am. Nat. 155:2141–53 [Google Scholar]
  95. Schwartz CC, Haroldson MA, White GC. 2010. Hazards affecting grizzly bear survival in the Greater Yellowstone Ecosystem. J. Wildl. Manag. 74:4654–67 [Google Scholar]
  96. Schwartz CC, Haroldson MA, White GC, Harris RB, Cherry S. et al. 2006. Temporal, spatial, and environmental influences on the demographics of grizzly bears in the Greater Yellowstone Ecosystem. Wildl. Monogr. 161:1–68 [Google Scholar]
  97. Seager ST, Eisenberg C, St Clair SB. 2013. Patterns and consequences of ungulate herbivory on aspen in western North America. For. Ecol. Manag. 299:81–90 [Google Scholar]
  98. Severud WJ, Belant JL, Bruggink JG, Windels SK. 2011. Predator cues reduce American beaver use of foraging trails. Hum. Wildl. Interact. 5:2296–305 [Google Scholar]
  99. Shelton PC. 1962. Ecological studies of beavers, wolves, and moose in Isle Royale National Park, Michigan PhD thesis, Purdue Univ., Lafayette, IN [Google Scholar]
  100. Silliman BR, Angelini C. 2012. Trophic cascades across diverse plant ecosystems. Nat. Educ. Knowl. 3:1044 [Google Scholar]
  101. Sinclair ARE, Mduma S, Brashares JS. 2003. Patterns of predation in a diverse predator-prey system. Nature 425:6955288–90 [Google Scholar]
  102. Singer FJ, Harting A, Symonds KK, Coughenour MB. 1997. Density dependence, compensation, and environmental effects on elk calf mortality in Yellowstone National Park. J. Wildl. Manag. 61:12–25 [Google Scholar]
  103. Smith DW, Stahler DR, Stahler E, Metz M, Quimby K. et al. 2013. Yellowstone Wolf Project: Annual Report, 2012 Natl. Park Serv., Yellowstone Cent. Resour., Yellowstone Natl. Park [Google Scholar]
  104. Tercek MT, Stottlemyer R, Renkin R. 2010. Bottom-up factors influencing riparian willow recovery in Yellowstone National Park. West. N. Am. Nat. 70:3387–99 [Google Scholar]
  105. Thompson DW. 1942. On Growth and Form Cambridge, UK: Cambridge Univ. Press, 2nd. ed. [Google Scholar]
  106. Valeix M, Loveridge AJ, Chamaille-Jammes S, Davidson Z, Murindagomo F. et al. 2009. Behavioral adjustments of African herbivores to predation risk by lions: spatiotemporal variations influence habitat use. Ecology 90:23–30 [Google Scholar]
  107. Vucetich JA, Hebblewhite M, Smith DW, Peterson RO. 2011. Predicting prey population dynamics from kill rate, predation rate and predator-prey ratios in three wolf ungulate systems. J. Anim. Ecol. 80:61236–45 [Google Scholar]
  108. Vucetich JA, Nelson MP, Peterson RO. 2012. Should Isle Royale wolves be reintroduced? A case study on wilderness management in a changing world. George Wright Forum 29:126–47 [Google Scholar]
  109. Vucetich JA, Peterson RO. 2004a. The influence of prey consumption and demographic stochasticity on population growth rate of Isle Royale wolves (Canis lupus). Oikos 107:309–20 [Google Scholar]
  110. Vucetich JA, Peterson RO. 2004b. The influence of top-down, bottom-up, and abiotic factors on the moose (Alces alces) population of Isle Royale. Proc. R. Soc. Lond. B 271:183–89 [Google Scholar]
  111. Vucetich JA, Peterson RO. 2005. The wolves of Isle Royale.. Annu. Rep. 2004–2005 Michigan Technol. Univ., Houghton, Mich. [Google Scholar]
  112. Vucetich JA, Peterson RO, Nelson MP. 2013a. Discernment and precaution: a response to Cochrane and Mech. George Wright Forum 30:3333–40 [Google Scholar]
  113. Vucetich JA, Peterson RO, Nelson MP. 2013b. Response to Gostomski. George Wright Forum 30:101–02 [Google Scholar]
  114. Vucetich JA, Peterson RO. 2014. The wolves of Isle Royale. Annu. Rep. 2013–2014, Mich. Technol. Univ., Houghton, Mich. [Google Scholar]
  115. Vucetich JA, Smith DW, Stahler DR. 2005. Influence of harvest, climate, and wolf predation on Yellowstone elk, 1961–2004. Oikos 111:2259–70 [Google Scholar]
  116. Wagner FH. 2006. Yellowstone's Destabilized Ecosystem: Elk Effects, Science, and Policy Conflict New York: Oxford Univ. Press [Google Scholar]
  117. White PJ, Garrott RA. 2005. Yellowstone's ungulates after wolves—expectations, realizations, and predictions. Biol. Conserv. 125:141–52 [Google Scholar]
  118. White PJ, Garrott RA, Hamlin KL, Cook RC, Cook JG, Cunningham JA. 2011. Body condition and pregnancy in northern Yellowstone elk: evidence for predation risk effects?. Ecol. Appl. 21:3–8 [Google Scholar]
  119. White PJ, Proffitt KM, Lemke TO. 2012. Changes in elk distribution and group sizes after wolf restoration. Am. Midl. Nat. 167:174–87 [Google Scholar]
  120. Willems EP, Hill RA. 2009. Predator-specific landscapes of fear and resource distribution: effects on spatial range use. Ecology 90:546–55 [Google Scholar]
  121. Wilmers CC, Crabtree RL, Smith DW, Murphy KM, Getz WM. 2003a. Trophic facilitation by introduced top predators: grey wolf subsidies to scavengers in Yellowstone National Park. J. Anim. Ecol. 72:6909–16 [Google Scholar]
  122. Wilmers CC, Post E, Peterson RO, Vucetich JA. 2006. Predator disease out break modulates top down, bottom up and climatic effects on herbivore population dynamics. Ecol. Lett. 9:4383–89 [Google Scholar]
  123. Wilmers CC, Stahler DR, Crabtree RL, Smith DW, Getz WM. 2003b. Resource dispersion and consumer dominance: scavenging at wolf and hunter killed carcasses in Greater Yellowstone, USA. Ecol. Lett. 6:11996–1003 [Google Scholar]
  124. Winnie JA. 2012. Predation risk, elk, and aspen: tests of a behaviorally mediated trophic cascade in the Greater Yellowstone Ecosystem. Ecology 93:2600–14 [Google Scholar]
  125. Wittmer HU, Sinclair AR, McLellan BN. 2005. The role of predation in the decline and extirpation of woodland caribou. Oecologia 144:2257–67 [Google Scholar]
  126. Wolf EC, Cooper DJ, Hobbs NT. 2007. Hydrologic regime and herbivory stabilize an alternative state in Yellowstone National Park. Ecol. Appl. 17:61572–87 [Google Scholar]
  127. Wright GJ, Peterson RO, Smith DW, Lemke TO. 2006. Selection of northern Yellowstone elk by gray wolves and hunters. J. Wildl. Manag. 70:41070–78 [Google Scholar]
  128. Yellowstone Natl. Park 1997. Yellowstone's Northern Range: Complexity and Change in a Wildland Ecosystem. Mammoth Hot Springs, WY: Natl. Park Serv. [Google Scholar]

Data & Media loading...

Supplementary Data

  • Article Type: Review Article
This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error