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Article

Author(s): Sabrina Streif, Annette Kohnen, Carolin Wilhelm
Editorial office: FVA, Germany
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The European Wildcat in the Upper Rhine Valley and region Kaiserstuhl

Its spatial organization in a highly fragmented landscape

Since 1912, the European Wildcat (Felis silvestris silvestris) was considered to be extinct in Baden-Württemberg for almost a century. In 2006 and 2007 two carcasses were found in the Upper Rhine Valley and genetically identified as pure wildcats. Ever since, continuous evidence of its occurrence has been found.

Content

Europäische Wildkatze (Felis s. sylvestris)
Fig. 1: The European Wildcat  (Felis s. silvestris). (Photo: K. Echle)

The known occurrence of the wildcat in Baden-Württemberg mainly ranges from Lörrach to Karlsruhe along the Upper Rhine Valley. Sporadic evidence has been found over the whole state indicating either solitary dispersing individuals or small groups resulting from recent dispersals from the Upper Rhine Valley or from neighboring populations in Bavaria or Switzerland.

Wildkatzenvorkommen in Baden-Württemberg und angrenzenden Ländern (Stand 2016)
Fig. 2: Distribution of the European wildcat in Baden-Württemberg and bordering areas (2016).

In Germany, wildcats inhabit areas with contiguous forests. Their core distribution is mainly in the Pfälzer Wald, the Eifel and the Harz region. In contrast, the Upper Rhine Valley represents a highly-fragmented landscape with intensive agriculture and a high density of roads and human settlements with only small forest patches along the Rhine River.

Between 2010 and 2015, a research project was conducted in the Kaiserstuhl region and adjacent floodplain forests to investigate the spatio-temporal behavior and habitat use of wildcats in the patchy forests using GPS- telemetry. Furthermore, the connectivity to wildcat populations of neighbouring countries (France and Switzerland) was studied using genetic analyses to gain information about the origin of this recolonizing population.

Twenty-one individuals were captured in wooden live-traps and fitted with GPS collars. For genetic analysis, a blood sample was taken. The periods in which the wildcats could be observed via telemetry ranged between two weeks and almost two years. The short periods are due to the loss of the collar or the death of the individual. Most of the individuals were captured twice in order to remove the collar.

Space Use of Wildcats in Highly Anthropogenic Cultivated Landscape

The results of the telemetry study suggested that wildcats were able to occupy habitats in the sparsely forested cultural landscape of the Upper Rhine Valley. However, wildcats’ habitat use was limited almost exclusively to forested areas or places with a high proportion of shelter. Spatial organization of the collared individuals within the study area was comparable to other studies. However, home range sizes were smaller compared to those reported in studies in contiguous forests in Europe. Reasons for smaller home ranges in the floodplain forests could be explained by the high structural diversity and high prey abundance within the study area.

Wildcats prefer high structural cover to cross open plains and agricultural areas.
Fig. 3: Wildcats were captured in wooded traps and were tagged with GPS-collars to study their habitat use. (Photo: K. Echle)
 
Wildcats prefer high structural cover to cross open plains and agricultural areas.
Fig. 4: Wildcats prefer high structural cover to cross open plains and agricultural areas.

Male wildcats especially were less restricted to forested habitats and were frequently found in open landscape habitats along field margins and hedgerows. In contrast, the use of open landscape habitats by females was very rare and no agricultural areas were traversed. The results of the study also emphasized the threat of roads, especially in fragmented landscapes where road density is high. Three of the collared males as well as seven unknown wildcats (which were detected within the monitoring program) were killed by cars.

Recolonization of the Wildcat

Genetic analyses show that there was no genetic differentiation between individuals of the Upper Rhine Valley and individuals inhabiting the Vosges (France) and the Jura Mountains (Switzerland). Thus, we can assume that the Rhine River did not act as a barrier and both populations were sufficiently interconnected to facilitate adequate dispersal and gene flow. The lack of wildcat occurrence outside the Upper Rhine Valley and the genetic attributes of the two populations support the hypothesis that the wildcat was extinct in Baden-Württemberg and has recolonized its former habitat in recent years.

We found introgression in the wildcat population of the Upper Rhine Valley to be ten percent. A small proportion of hybrids in a population is often detected after dispersal events and can even facilitate colonizing new habitats. Therefore, the small hybridization rate was not considered as a threat, but for a successful recolonization of the wildcat in Baden-Württemberg, hybridization processes need to be monitored in the long term.

Conclusion

The highly-fragmented landscape in the Upper Rhine Valley shows that it can be suitable habitat for a wildcat population. However, the success of a long term recolonization of its former habitat is highly dependent on the structural diversity in forested areas as well as the connectivity of those habitats.

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