Effects of El Niño on the population dynamics of the Malay civet east of the Wallace line

Abstract

The effect of climate on the population dynamics of rainforest vertebrates is known only for a limited subset of species and study locations. To extend this knowledge, we carried out an 8-year population study of a Viverrid (Malay civet Viverra tangalunga) in the Wallacea biogeographical region (Buton Island, Sulawesi). Civets were trapped annually from 2003 to 2010, during which there were four weak to moderate El Nino events and one moderate La Nina event. In Indonesia, El Nino events are associated with drier than normal conditions, while La Nina is associated with wetter conditions. The number of individuals captured was strongly correlated with the 12-month summed Southern Oscillation Index (SOI) prior to trapping, with significantly fewer individuals caught in years with lower summed SOI (i.e. stronger El Nino conditions). Adult civet body mass was significantly higher in El Nino years; mean adult male and female body masses were 10.6% and 4.0% greater in El Nino years. There was support for a 1-year time lagged effect of El Nino on the apparent survival (1 – probability of disappearing from the study site due to death or emigration) of male (but not female) civets, which was approximately 50% higher in the year following El Nino events. Using spatially explicit capture–mark–recapture models, we were unable to detect any significant change in civet density between years, which was estimated as 1.36 ± 0.14 (se) individuals km−2. We suggest that increased apparent survival of males observed in the year after El Nino events was brought about by reduced dispersal (possibly associated with a change in mating tactic) rather than reduced mortality.