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A population survey of the Critically Endangered Macaca nigra within the KPHK reserve, Tangkoko, north Sulawesi, following the most recent El Niño (2015) event

Anna Starky, MSc student, Liverpool John Moores University, UK

Anna Starkey 250x320Macaca nigra is the most threatened of the seven endemic macaque species in Sulawesi. As anthropogenic threats continue to be a problem for the species, it is vital that regular surveys are carried out to be aware of their abundance in order to understand the effects of current and ongoing threats and to apply appropriate and effective conservation management.

A line-transect survey using distance sampling (between July and August 2017) was carried out in KPHK Tangkoko Reserve to obtain a reliable estimate of the M. nigra population. Data was then compared with a previous survey which used a similar approach, most recently in 2010, to determine any increases/decreases in abundance. The effects of El Niño 2015 on vegetation condition and meteorological measures were also assessed using radiances measured by the Advance Very High Resolution Radiometer (AVHRR) on NOAA operational orbiting environmental satellites, provided by NOAA STAR (National Oceanic and Atmospheric Administration - Center for Satellite Applications and Research) and climatic data recorded in KPHK. Abundance has decreased by 21%, which was evident across 80% of transects walked. Density of individuals has decreased by 20% and cluster size have on average decreased by almost 5 fold. The main contributors to their decline are thought to be the continuation of hunting and habitat disturbances i.e. logging and land conversion. Analysis of climate data from before, during and after El Niño provided evidence that climate change is altering M. nigra habitat by increasing fire risk and intensifying drought. Collectively these factors reduce vegetation condition. There was no evidence for El Niño 2015 contributing to their decline, however, it is predicted populations will suffer from projected future increases in frequency and intensity of El Niño events. For M. nigra to recover and remain stable in the future, it is recommended that current conservation strategies are continued to be developed and regularly reviewed.