From faeces to ecology and behaviour : non-invasive microsatellite genotyping as a means to study wild otters (lutra lutra)
The threatened Eurasian otter (Lutra lutra) is of high conservation concern because of its earlier massive decline and range contractions, its important role as a top predator in its ecosystem, and because of its current increase and expansion in Germany that evokes conflicts with humans living on aquaculture. To understand the population dynamic and hence the current spread and to be able to manage it, we require knowledge that is either unavailable, not well understood, or has to be checked whether it also applies to fish pond systems, the main otter habitat in the Upper Lusatia that is the main source population for the recent expansion in Saxony, Germany. For this purpose, I used non-invasive genetic CMR methods to gain information about actual population sizes, population dynamic parameters, marking behaviour, and spatial use of one source population in Eastern Germany. To make this method more efficient, especially for otter scats, I first optimised the required genetic methods to receive high success rates and low genotyping errors rates (Chapter two). Following this, I applied non-invasive genetic CMR to the first sampling year (2006) to demonstrate pitfalls and risks of this method and present a road map in which I offer solutions for the outlined problems (Chapter three). This road map is not only valid for otters, but is written as a general guideline when using non-invasively collected samples with low quality. Finally, I used this road map to obtain reliable estimates and information on population size, sex ratio, and marking behaviour (Chapter four), as well as survival, temporary migration, dispersal, and spatial use (Chapter five) over six sampling years (2006–2012). Chapter six completes the thesis by first giving an overview of the conducted research, followed by a synthesis of the four key findings and a discussion about limitations and methodological constraints. The chapter closes with suggestions for further research and for otter conservation.