Domestic cats and predation on a free-ranging primate, Gursky’s tarsier (Tarsius spectrumgurskyae)

Introduced species, also known as invasive species, alien species and exotic species, are a major contributing factor to environmental problems in that they modify or disrupt the ecosystem they colonize. While some invasive species arrive in new areas through natural migration, more often than not they are introduced by the activities of humans. For example, domestic cats (Felis catus) were introduced by humans and are now common pets. Cats have been so successful invading new areas that their worldwide population is reported to exceed 500 million. Over 3 decades of u observations, cats were observed 169 times while observing Gursky's tarsier. Over time, the frequency that cats were observed while observing tarsiers increased. Similarly, the distance from the village that cats were observed increased over time indicating that the cats are moving further into the protected area. The tarsiers exhibited numerous responses to the presence of a cat. They always alarm called, and occasionally mobbed the cat. Several behavioral changes were made including increasing time traveling, increasing their height in the forest canopy, decreasing distance between group members. The cats attempted to prey on a tarsier 19 times. Twelve attempts were successful. Given that cat predation is known to have already caused faunal extinctions on islands, this threat to the tarsiers and other endemic species in Tangkoko Nature Reserve should not be taken lightly. One potential way to mitigate the negative impacts of cats on the tarsier population is by developing bylaws that restrict cat ownership adjacent to protected areas.