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Providing evidence to improve practice

Individual study: Reintroducing the gray wolf to Central Idaho and Yellowstone National Park

Published source details

Bangs E.E. & Fritts S.H. (1996) Reintroducing the gray wolf to Central Idaho and Yellowstone National Park. Wildlife Society Bulletin, 24, 402-413


This study is summarised as evidence for the intervention(s) shown on the right. The icon shows which synopsis it is relevant to.

Release translocated/captive-bred mammals in family/social groups Terrestrial Mammal Conservation

A replicated study in 1995–1996 in two forest sites in Idaho and Wyoming, USA, (Bangs & Fritts 1996) found that translocated gray wolves Canis lupus had similar survival rates and breeding success in the first two years after release when adult family groups were released together from holding pens or when young adults were released directly into the wild. No statistical analyses were conducted. Thirty out of 35 young adult wolves released directly into the wild were still alive seven months after the last releases, and had produced up to 40 pups from 3-8 pairs. Thirty-one adult wolves released from holding pens in family groups had produced 23 pups four months after the last releases. From these 54 animals, nine had died. Six of the seven adult pairs released together from holding pens remained together, and five of these pairs established territories in the vicinity of the pens. Wolves were wild-caught from Canada in January 1995 and 1996. In Idaho, young adults were directly released in January 1995 and 1996. In Wyoming, family groups of 2–6 wolves spent 8–9 weeks in 0.4-ha chain-link holding pens before release in March 1995 and April 1996. Wolves were radio-tracked every 1–3 weeks until August 1996.

(Summarised by Matt Rogan)

Use holding pens at release site prior to release of translocated mammals Terrestrial Mammal Conservation

A replicated study in 1995–1996 in two forest sites in Idaho and Wyoming, USA (Bangs & Fritts 1996) found that translocated gray wolves Canis lupus had similar survival rates and breeding success in the first two years after release when adult family groups were released together from holding pens or when young adults were released directly into the wild. No statistical analyses were conducted. Thirty out of 35 young adult wolves released directly into the wild were still alive seven months after the last releases, and had produced up to 40 pups from 3-8 pairs. Thirty-one adult wolves released from holding pens in family groups had produced 23 pups four months after the last releases. From these 54 animals, nine had died. Six of the seven adult pairs released together from holding pens remained together, and five of these pairs established territories in the vicinity of the pens. Wolves were wild-caught from Canada in January 1995 and 1996. In Idaho, young adults were directly released in January 1995 and 1996. In Wyoming, family groups of 2–6 wolves spent 8–9 weeks in 0.4-ha chain-link holding pens before release in March 1995 and April 1996. Wolves were radio-tracked every 1–3 weeks until August 1996.

(Summarised by Matt Rogan)