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Individual study: Successful swift fox Vulpes velox reintroductions on the Blackfeet Indian Reservation, Montana, USA

Published source details

Ausband D.E. & Foresman K.R. (2007) Swift fox reintroductions on the Blackfeet Indian Reservation, Montana, USA. Biological Conservation, 136, 423-430


Swift foxes Vulpes velox once occurred commonly on prairie grasslands throughout western North America. They are of cultural importance to Blackfeet Indians (and some other Native American tribes). In response to extirpation from their tribal lands in Montana (USA), and Montana State as a whole by the mid-1950s, the Blackfeet Tribe and Defenders of Wildlife reintroduced 123 captive-raised swift foxes from 1998 to 2002 to the Blackfeet Indian Reservation. After the fifth year of releases, the Blackfeet Tribe and Defenders of Wildlife wanted to determine if the reintroduction was successful. Therefore a programme of monitoring was undertakenfrom 2003 to 2005.

Study area: The swift fox reintroductions took place on the Blackfeet Indian Reservation in Glacier County, Montana, northwest USA. The Reservation comprises 607,000 ha of mostly grassland habitat with some cropland. All swift foxes were released on a 3,200 ha tribally owned ranch located along the Two Medicine River approximately 30 km southeast of the town of Browning.

Releases and monitoring: From 1998 to 2002, 123 mostly juvenile (89%), captive-raised swift foxes (66 females and 57 males), from Cochrane Ecological Institute, Canada were released. Subsequent monitoring located natal dens and wild-born kits every year from 1999 to 2002.

To determine if the reintroduction was successful, a combination of radio-tracking and field observations from 2003 to 2005 were undertaken to estimate survival, fecundity and population size.

The swift fox population grew at a rate of 16% during 2003/2004 and 14% in 2004/2005. In the summer of 2005, 93 foxes were observed, and this in combination with additional swift fox sign in areas where direct observations had not been made, suggested that there were 100 individuals present in this year. Indications of swift fox presence were found up to 110 km from the release site, and they now range beyond the Reservation border to the Rocky Mountain Front.

Given the population growth rates, the number of direct and indirect observations, and the apparent increasing area of occupancy, this reintroduction is considered a success, at least in the short-term.

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