Influence of prerelease experience on reintroduced black-footed ferrets (Mustela nigripes)

Captive breeding is increasingly being used to create supplies of endangere d animals for release into natural habitats, but rearing strategies vary an d debates arise over which methods an most efficient. We assessed postrelea se behaviors and survival of three groups of black-footed ferrets,each with different prerelease experience. Eighteen ferret kits less than or equal t o 60 days of age were moved with their dams from cages to 80-m(2) outdoor p ens with prairie dog burrows. These animals were compared to animals reared in standard cages (n = 72), some of which were given experience killing pr airie dogs (n = 32). Ferrets were released onto white-tailed prairie dog (C ynomys leucurus) colonies in Wyoming, USA, in fall, 1992. Radio-tagged cage -reared ferrets made longer nightly moves and dispersed further from releas e sites than their pen-reared counterparts. The band return rate was 4-fold higher for pen-reared animals than for cage-reared animals during surveys conducted about 1 month after release. We recommend routine use of quasi-na tural outdoor pens for prerelease conditioning of black-footed ferrets. Pub lished by Elsevier Science Ltd.