Amphibia-Reptilia 31 (2010): 229-237 A comparison of external and internal attachments of radio transmitters on adult crested newts Triturus cristatus Børre Dervo 1 , Jon K. Skei 2,3 ,∗ , Ole K. Berg 2 , Morten Kraabøl 1,3 , Jon M. Arnemo 4,5 , Dag Dolmen 3 Abstract. Telemetry studies of newt species demand small transmitters. Two types of external attachments (sutured to epidermis and backpack) and traditional implanting in the peritoneal cavity were tested between groups of 5 adult individuals of the crested newt Triturus cristatus (mass 6-15 g) held in terrariums under controlled environmental conditions. The newts were anaesthetized with 1.5 g l −1 MS222, delivered in water and buffered to pH 6.9 by Na 2 CO 2 . Surgical plane of anaesthesia was achieved after 5-12 minutes and lasted for 30-60 minutes. External tagging proved unsuitable because transmitters became entangled in vegetation, and all animals shed their transmitters shortly after tagging, except for one that died. Transmitters that were surgically implanted in the peritoneal cavity were more successful. By the fourth day following surgery, the animals that had undergone surgery behaved similarly to control animals with respect to the use of cover. Two of the newts died, however, without showing any signs of illness in advance, and the cause of death could not be established. Based on the present experiments and published studies, implantable transmitters appear to be the best method for radiotagging small and medium sized urodele species such as T. cristatus, to gain crucial information on spatio-temporal terrestrial activity patterns, habitat utilization and hibernation sites. Additional research is needed to evaluate both short and long term effects on activity, behaviour and survival. Keywords: Amphibia, anaesthesia, conservation biology, telemetry, transmitter attachment. Introduction Studies dealing with individual movements form the basis for understanding and predict- ing habitat preferences and connectivity among populations of amphibians in various land- scapes (Gibbs, 1998; Semlitsch, 1998, 2000). Movement studies involving telemetry provide precise information for scaling up from the in- dividual to population level. Newt species in temperate regions have a complex life cycle, alternating between aquatic 1 - Norwegian Institute of Nature Research, Human Di- mension Department, Fakkelgården, NO-2624 Lille- hammer, Norway 2 - Norwegian University of Science and Technology, De- partment of Biology, NO-7491 Trondheim, Norway 3 - Norwegian University of Science and Technology, Mu- seum of Natural History and Archaeology, NO-7491 Trondheim, Norway 4 - Faculty of Forestry and Wildlife Management, Hed- mark University College, Campus Evenstad, NO-2418 Elverum, Norway 5 - Department of Wildlife, Fish and Environmental Stud- ies, Faculty of Forest Sciences, Swedish University of Agricultural Sciences, SE-901 83 Umeå, Sweden ∗ Corresponding author; e-mail: krisskei@online.no and terrestrial stages. These habitat changes imply specific conservation challenges as both habitats and their connections have to be intact for surviving populations (Becker et al., 2007; Fonseca et al., 2008). To gain knowledge on newt habitat use, it is essential to obtain ade- quate data from all stages of the life cycle. The crested newt Triturus cristatus (Laurenti, 1768) is a threatened species in most of its range (Edgar and Bird, 2006), and the species is classified as vulnerable on the Norwegian Red List (Dolmen, 2006). The aquatic activity of the species is relatively well known considering the rarity of data concerning the use of the ter- restrial habitat, where the species spends most of its life cycle (Jehle, 2000; Schabetsberger et al., 2004). Information on temporal and spatial patterns of microhabitat use and activity range is needed to develop appropriate conservation measures for the species. The need for detailed information on life-history, such as habitat use and dispersal behaviour, has been highlighted for some time (Madison, 1997; Rowley and Al- © Koninklijke Brill NV, Leiden, 2010. Also available online - www.brill.nl/amre