Mapping the spatial configuration of hybridization risk for an endangered population of the European wildcat (Felis silvestris silvestris) in Scotland
Kilshaw K., Montgomery RA., Campbell RD., Hetherington DA., Johnson PJ., Kitchener AC., Macdonald DW., Millspaugh JJ.
© 2015, Mammal Research Institute, Polish Academy of Sciences, Białowieża, Poland. The wildcat in Scotland, UK, is currently at risk of extinction because of hybridization with feral domestic cats (ferals) and hybrids (wildcat × domestic cat crosses). Conservation efforts are hampered by limited information on the distribution of these three cat types and the spatial variation in hybridization risk. From January 2010 to July 2013, we conducted widespread camera-trapping surveys throughout northern Scotland to document the distribution of ferals, hybrids, and wildcats. Using single-season occupancy models, we predicted the probability of occupancy for these three cat types across Scotland. Over 49,031 camera-trapping days, we had 87 captures (photo of a cat at a camera-trap station within a 24-h period) of wildcats, 145 captures of hybrids, and 193 captures of ferals. At over 48 % of the camera-trap stations where we detected wildcats, we also detected ferals or hybrids. We predicted wildcat occupancy as a function of habitat covariates. Wildcat occupancy probability increased in habitat with a higher proportion of mixed woodland habitat and decreased in habitat with more edge (transition from closed to open habitats). Hybrids showed a clear overlap in their distribution pattern with both ferals and wildcats. The results indicate that wildcats in Scotland are at risk of hybridization across much of their current distribution from ferals and/or hybrids. In particular, hybrids have an increased probability of occupying much of the same habitat as wildcats compared to ferals, supporting recent suggestions that hybrids may pose a significant additional hybridization threat by facilitating gene flow between wildcats and ferals.