Cage trapping and field anaesthesia of brown bears as part of nuisance bear management

Abstract

The population and distribution of the European brown bear (Ursus arctos) in Slovakia are expanding as bears were observed beyond the southern border of the country in Hungary. This study presents the authors' experience with field anaesthesia of wild brown bears trapped in a custom-made container trap and of free-ranging individuals. A total of 25 bears were captured and translocated using a specially designed metal cage trap. The study compared the effectiveness of three anaesthetic protocols in managing both free-ranging and trapped bears. For juveniles, or small adults up to 70 kg body weight (BW), ketamine-xylazine mixture was used at doses of 3.0-4.0 mg kg-1 ketamine and 1.0-1.5 mg kg-1 xylazine BW. The immobilisation of free-ranging bears, which are usually attracted by municipal solid garbage, was performed remotely using PneuDart darts with 2-3 ml of anaesthetics. For this purpose, tiletamine-zolazepam-detomidine (T-Z-D) was preferred at a dose of 1.7-2.5 (T) mg kg-1, 1.7-2.5 (Z) mg kg-1, and 0.1-0.2 (D) mg kg-1 BW. Induction time was from 7 to 18 min post darting with the average of 12.04 min. The same combination was applied to bears trapped in a container trap, with anaesthesia lasting from 40 to 150 min. If T-Z-D was used, no further anaesthetic was needed. In all cases, anaesthesia was antagonised by atipamezole at a dose of 0.15-0.225 mg kg-1 BW. Atipamezole was injected at a half dose intramuscularly and a half dose subcutaneously at the time when the palpebral reflex reappeared and the bear was able to move his tongue. It was shown that the T-Z-D mixture is a safe, low-volume anaesthetic darting protocol that is reversible, has minimal adverse effects on physiological parameters, and has a sufficient duration. The results can be used to manage large carnivore populations in the Carpathian region.

Keywords: European brown bear; Zoletil; cage trap; detomidine; immobilisation; xylazine.