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Individual study: Reintroduction of swift foxes Vulpes velox to Grassland National Park, Saskatchewan, Canada

Published source details

Smeeton C. & Weagle K. (2000) The reintroduction of the swift fox Vulpes velox to south central Saskatchewan, Canada. Oryx, 34, 171-179

Summary

The swift fox Vulpes velox was extirpated from Canada in 1978, and by 1995 was considered to occupy less than 10% of its historical range in the USA. The causes of the swift fox's decline were attributed to the rapid change of the Great Plains from native prarie grasslands into farmland, and accompanying hunting, trapping and poisoning. The aim of the National Recovery Plan for the swift fox in Canada was to establish a viable self-sustaining population distributed across the Canadian Prairies within its formwer range. A reintroduction attempt entailing releases of foxes of both captive-bred and wild translocated individuals between 1989-1997 in Saskatchewan is described here.

The swift fox Vulpes velox reintroduction took place in the East Block and West Block areas of the Grassland National Park in south-central Saskatchewan, Canada. Realease were made in the years 1990 to 1997.

Release methods:

‘Hard-release’ - foxes were taken from a captive breeding colony and transported in plastic transport kennels (wherein they remained up to 58 h) prior to liberation at the selected release site;

‘PPS-release' - portable protective shelters (PPS) was placed at each pre-selected release site no more than two days prior the release. The PPS were left at the release sites for a minimum of four days after the release. On the release date the animals were loaded into individual plastic transport kennels and transported to the release sites with PPS, where they could come out of their kennels in their own time. After release, the foxes were monitored for 24 h.

Release season: In an attempt to determine the most suitable time of year for releases, a study was conducted during 1989-91.  The releases of captive-bred juveniles and wild translocated adults (from Colorado and Wyoming, USA) were compared.

Spring releases (1989-91) included: 33 adult wild foxes; 41 captive-raised juveniles born the previous year; and
122 captive-bred adult foxes

Autumn releases included: 58 adult wild foxes and 81 captive-raised juveniles.
 

In total, 126 foxes (14 wild translocated foxes and 112 captive-bred foxes) were released in 1990-91 using the ‘hard-release’ method. The government agencies continued to release swift foxes into the East Block area until 1997 using the ‘PPS-release’ method. From 1992 until 1997 the CEI released captive-bred foxes only in the West Block using the ‘PPS-release’ method (Table 1, attached).

Fox establishment: The Grasslands National Park had a density of 2.2 swift foxes/sq km, and a population of 87 individuals in 1997. A swift fox population in south-central Saskatchewan has become re-established, but numbers are low making long-term survival uncertain.

The effectiveness of the ‘PPS-release’ method was still under review at the time of writing. Further evaluation of the methodology is necessary and is being carried out in conjunction with a new reintroduction project at the Blackfeet Reservation, Montana, USA (for a summary see: www.conservationevidence.com/ViewEntry.asp?ID=1251).

Spring and autumn releases: Of those foxes released in spring, survival was much higher for wild translocated adults (58.9%) than that of captive-raised juveniles (7.4%). However, survival of juveniles was much higher (39.7%) when they were released in the autumn.

Conclusions: Captive-bred swift foxes appeared less suitable for reintroduction than wild adult translocated foxes. However captive-bred animals faired much better when released in the autumn when survival was consequently much higher, as compared to spring released individuals.


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