Trophic cascades in Yellowstone: the first 15 years after wolf reintroduction

  • Published source details Ripple W.J. & Beschta R.L. (2012) Trophic cascades in Yellowstone: the first 15 years after wolf reintroduction. Biological Conservation, 145, 205-213.


This study is summarised as evidence for the following.

Action Category

Translocate predators for ecosystem restoration

Action Link
Terrestrial Mammal Conservation
  1. Translocate predators for ecosystem restoration

    A before-and-after study in 1990–2010 of riparian and adjacent upland habitat in a national park in Wyoming, USA (Ripple & Beschta 2012) found that following reintroduction of wolves Canis lupus, populations of beavers Castor canadensis and bison Bison bison increased. There were more beaver colonies in a monitored area 13 years after wolf reintroduction began (12 colonies) than at the start of reintroduction (one colony). Average summer bison counts were higher in the decade after wolf reintroduction began (1,385 bison) than in the preceding decade (708 bison). Following the start of reintroduction in 1995–1996, wolf numbers in the study area increased to 98 in 2003, followed by a decline and substantial fluctuations. Their establishment was associated with a fall in elk Cervus canadensis numbers from >15,000 in the early 1990s to approximately 6,100 in 2010. Elk browsing on woody vegetation reduced, increasing resources available to beaver and bison. Beaver and bison numbers were derived from annual surveys.

    (Summarised by: Nick Littlewood)

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