Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Ecosystem consequences of wolf behavioural response to climate


Because apex predators exert considerable influence on the structure and function of top-down ecosystems1,2,3, their responses to climate may shape responses at lower trophic levels4. Previous reports of trophic cascades and ecosystem dynamics induced by predators have focused on changes in their abundance5,6,7,8, whereas we investigated whether changes in predator behaviour could precipitate cascades of similar ecological scale. Here we report the ecological consequences of predator behavioural response to global climatic variation using 40 years of data on wolf predation from Isle Royale, USA, where wolves limit abundance of moose9, which limit productivity of fir trees10. In response to increases in winter snow related to the North Atlantic Oscillation, wolves hunted in larger packs and, consequently, tripled the number of moose killed per day compared with less snowy years when they hunted in smaller packs. Following increased predation rates, moose abundance declined, and, following release from heavy browsing, growth of understory fir increased. Hence, cascading behavioural responses of apex predators may be a substantial link in the pathway from climatic change to ecosystem function.

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Figure 1: Dynamics of the three-trophic-level system on Isle Royale, USA, and the North Atlantic Oscillation index, 1958–97.
Figure 2: Progression of climatic influence on ecosystem function from wolf behaviour to growth of fir trees.


  1. 1

    Estes,J. A. & Palmisano,J. F. Sea otters: their role in structuring nearshore communities. Science 185, 1058–1060 (1974).

    ADS  CAS  PubMed  Google Scholar 

  2. 2

    Spiller,D. A. & Schoener,T. W. A terrestrial field experiment showing the impact of eliminating top predators on foliage damage. Nature 347, 469–472 (1990).

    ADS  Google Scholar 

  3. 3

    McPeek,M. A. The consequences of changing the top predator in a food web: a comparative experimental approach. Ecol. Monogr. 68, 1–23 (1998).

    Google Scholar 

  4. 4

    Sanford,E. Regulation of keystone predation by small changes in ocean temperature. Science 283, 2095–2097 (1999).

    ADS  CAS  PubMed  Google Scholar 

  5. 5

    Paine,R. T. Food web complexity and species diversity. Am. Nat. 100, 65–75 (1966).

    Google Scholar 

  6. 6

    Paine,R. T. Intertidal community structure: Experimental studies on the relationship between a dominant competitor and its principal predator. Oecologia 15, 93–120 (1974).

    ADS  CAS  PubMed  Google Scholar 

  7. 7

    Estes,J. A. & Duggins,D. O. Sea otters and kelp forests in Alaska: generality and variation in a community ecological paradigm. Ecol. Monogr. 65, 75–100 (1995).

    Google Scholar 

  8. 8

    Estes,J. A., Tinker,M. T., Williams,T. M. & Doak,D. F. Killer whale predation on sea otters linking oceanic and nearshore ecosystems. Science 282, 473–476 (1998).

    ADS  CAS  PubMed  Google Scholar 

  9. 9

    Post,E. & Stenseth,N. C. Large-scale climatic variability and population dynamics of moose and white-tailed deer. J. Anim. Ecol. 67, 537–543 (1998).

    Google Scholar 

  10. 10

    McLaren,B. E. & Peterson,R. O. Wolves, moose, and tree rings on Isle Royale. Science 266, 1555–1558 (1994).

    ADS  CAS  PubMed  Google Scholar 

  11. 11

    Peterson,R. O. Wolf Ecology and Prey Relationships on Isle Royale (National Park Services Scientific Ser. No. 11, Washington DC, 1977).

    Google Scholar 

  12. 12

    Peterson,R. O., Page,R. E. & Dodge,K. M. Wolves, moose, and the allometry of population cycles. Science 224, 1350–1352 (1984).

    ADS  CAS  PubMed  Google Scholar 

  13. 13

    McLaren,B. E. & Janke,R. A. Seedbed and canopy cover effects on balsam fir seedling establishment in Isle Royale National Park. Can. J. For. Res. 26, 782–793 (1996).

    Google Scholar 

  14. 14

    Brandner,T. A., Peterson,R. O. & Risenhoover,K. L. Balsam fir on Isle Royale: effects of moose herbivory and population density. Ecology 71, 155–164 (1990).

    Google Scholar 

  15. 15

    McInnes,P. F., Naiman,R. J., Pastor,J. & Cohen,Y. Effects of moose browsing on vegetation and litter of the boreal forest, Isle Royale, Michigan, USA. Ecology 73, 2059–2075 (1992).

    Google Scholar 

  16. 16

    Pastor,J., Dewey,B., Naiman,R. J., McInnes,P. F. & Cohen,Y. Moose browsing and soil fertility in the boreal forests of the Isle Royale National Park. Ecology 74, 467–480 (1993).

    Google Scholar 

  17. 17

    Hurrell,J. W. Decadal trends in the North Atlantic Oscillation: regional temperatures and precipitation. Science 269, 676–679 (1995).

    ADS  CAS  Article  Google Scholar 

  18. 18

    Mech,L. D., McRoberts,R. E., Peterson,R. O. & Page,R. E. Relationship of deer and moose populations to previous winters' snow. J. Anim. Ecol. 56, 615–627 (1987).

    Google Scholar 

  19. 19

    Post,E. & Stenseth,N. C. Climatic variability, plant phenology, and northern ungulates. Ecology 80, 1322–1339.

  20. 20

    Peterson,R. O., Thomas,J. N., Thurber,J. M., Vucetich,J. A. & Waite,T. A. Population limitation and the wolves of Isle Royale. J. Mamm. 79, 828–841 (1998).

    Google Scholar 

  21. 21

    Thurber,J. M. & Peterson,R. O. Effects of population density and pack size on the foraging ecology of gray wolves. J. Mamm. 74, 870–889 (1993).

    Google Scholar 

  22. 22

    Schmidt,P. A. & Mech,L. D. Wolf pack size and food acquisition. Am. Nat. 150, 513–517 (1997).

    CAS  PubMed  Google Scholar 

  23. 23

    Peterson,R. O. & Page,R. E. The rise and fall of Isle Royale wolves, 1975–1986. J. Mamm. 69, 89–99 (1988).

    Google Scholar 

  24. 24

    Peterson,R. O. & Allen,D. L. Snow conditions as a parameter in moose-wolf relationships. Le Naturaliste Canadien 101, 481–492 (1974).

    Google Scholar 

  25. 25

    Kelsall,J. P. Structural adaptations of moose and deer for snow. J. Mamm. 50, 302–310 (1969).

    Google Scholar 

  26. 26

    Molvar,E. M. & Bowyer,R. T. Moose herbivory, browse quality, and nutrient cycling in an Alaskan treeline community. Oecologia 94, 472–479 (1993).

    ADS  PubMed  Google Scholar 

  27. 27

    Mech,L. D. The Wolf (Univ. Minnesota Press, 1970).

    Google Scholar 

  28. 28

    Ben-David,M., Bowyer,R. T., Duffy,L. K., Roby,D. D. & Schell,D. M. Social behavior and ecosystem processes: river otter latrines and nutrient dynamics of terrestrial vegetation. Ecology 79, 2567–2571 (1998).

    Google Scholar 

  29. 29

    Beckerman,A. P., Uriarte,M. & Schmitz,O. J. Experimental evidence for a behavior-mediated trophic cascade in a terrestrial food chain. Proc. Natl Acad. Sci. USA 94, 10735–10738 (1997).

    ADS  CAS  PubMed  Google Scholar 

  30. 30

    Schmitz,O. J., Beckerman,A. P. & O'Brien,K. M. Behaviorally mediated trophic cascades: effects of predation risk on food web interactions. Ecology 78, 1388–1399 (1997).

    Google Scholar 

Download references


We thank the U.S. National Science Foundation for grants to E.P. and R.O.P., the US National Park Service and Earthwatch for grants to R.O.P. and the Norwegian Science Council (NFR) for a grant to N.C.S. We thank G.-P. Saetre for discussions.

Author information



Corresponding author

Correspondence to Eric Post.

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Post, E., Peterson, R., Stenseth, N. et al. Ecosystem consequences of wolf behavioural response to climate. Nature 401, 905–907 (1999).

Download citation

Further reading


By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing