Research Group 1: Evolutionary Ecology

The Eurasian Otter Project

Investigations of wild otters (Lutra lutra L.)
in the Nossentiner / Schwinzer Heide national park(Mecklenburg-Western Pomrania)

Eurasian otter in the otter centre of Hankensbüttel

The Eurasian otter (Lutra lutra L.) is one of the most endangered mammalian species in Europe. But very little is known about the otters living conditions and environmental requirements compared with other large mammal species. The reason for this knowledge deficit is the relative unsuitability of common wildlife research methods for otters. Direct otter observation is rare, they are hard to distinguish visually and difficult to catch or trace by radio- tracking. We lack information about population density, spatial patterns, reproduction, causes and proportion of mortality and parameters for habitat quality, which are necessary for actions in conservation and control of their success.

We use a new non-invasive method in order to gather fresh data about free-living otters - avoiding any stress for the animals. Faecal samples from wild otters can be collected easily as they are the basis for intraspecific communication. As of recently it is possible to extract DNA material from faecal samples. Through genetic analysis we can identify and count the individuals from our study population, study their spatial movements as well as sex composition. So we can research otter populations with much better results than before. In addition we will monitor the numbers of surviving animals, those found dead and those that have disappeared in order to assess the influence of road kills and fish traps as mortality factors.

The nature park "Nossentiner / Schwinzer Heide" (Mecklenburg-Western Pomerania), is located between Goldberg, Dobbertin, Krakow am See und Waren on an area of 36.500 ha. There are 60 lakes with an area of 4.600 ha, 2.370 ha are nature reserve. Two rivers, Nebel and Mildenitz, flow through several lakes and create a system of habitats which is attractive not only for otters. Here we defined nearly 200 sample points with periodically control of spraints.

map of our study area with sample points

By microsatellite fingerprinting a DNA profiles of every otter individual will be established. By means of this database we can identify the donor animal of new samples.

DNA profiles of 18 samples from 15 otter individuals

In addition, hormonal pregnancy and stress tests on samples of individually known otters will follow. Otter carcasses from the same area were examined for selected diseases and parasites known to be indicative for a variety of ecological conditions. DNA profiles of dead otters were compared with those of known animals to investigate the influence of traffic accidents and fish traps on the mortality of otter populations. Informations about free-living specimens with regular occurrence are compared with data of dead found animals. The combination of all these results will not only increase the knowledge on habitat use, fitness parameters and causes of death but would also provide a deeper understanding of ecological requirements needed for the protection of these highly endangered animals.

During the first four months of our current study we analysed 48 spraint samples of which we identified 32 individuals. Four animals were resampled three times, five others twice. These results are useful to analyse time and spatial habitat use. According to the microsatellite data, marking points were frequented by up to nine individuals. Allelic pattern retrieved from dead found animals showed so far no match with already identified animals from the investigation area.