Choosing the best of both worlds

The great crested newt (Triturus cristatus) is dependent on two environments for its survival: the aquatic habitat necessary for breeding and development, and the terrestrialhabitat required for post-breeding and juvenile activities. For a population to be able to survive in a landscape, both habitat types must be present within migration distancefrom each other. The overall aim of this thesis is to find and describe prerequisites of environments and landscapes that make them sufficient as habitats for the great crestednewt. The purpose is also to present the results in a conservation perspective and to discuss them in relation to practical examples. In five separate studies, performed inÖrebro County, south-central Sweden, the aquatic and terrestrial habitats of the species were examined. The first study examined aquatic plants in a variety of ponds and landscapes, to determine if the diversity of plant species was higher in ponds where great crested newts were present. I found that ponds with newts had a significantlyhigher mean number of plant species than ponds without the species. The second study focused on the question if there are chemical and physical characteristics that determineoccurrence of great crested newts. The results showed that temperature and nutrient levels (nitrogen and phosphorus) were important in distinguishing between ponds withand without newts, whereas other physical variables were less important. My results also suggest that the great crested newt selects ponds with low nutrient levels forbreeding, while the species may also be present in ponds with higher nutrient levels. The third study used radio-telemetry in an attempt to determine how the great crestednewt moved in its terrestrial habitat and which micro-habitats it used while the focal point of study four was the landscape and if landscape composition may predict use of ponds as aquatic habitats. Combined, studies three and four suggest that management of the species should to a greater extent include terrestrial habitat, with special attention given to older, deciduous-rich forest within approximately 200 m of breeding ponds. The aim of the last study was to describe and evaluate a project concerningtranslocation of a great crested newt population. I point out the necessity of long-term monitoring to distinguish any possible success with respect to site sustainability andpopulation size.