The ecology of venom use in the Javan slow loris (Nycticebus javanicus) and its implications for conservation

• Main Author: Rode-Margono, Eva Johanna
• Other Authors: Nekaris, Anna ; Nijman, Vincent
• Published: Oxford Brookes University 2015
• Subjects: 300
• Online Access: https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.758007

The slow loris Nycticebus spp. belongs to the few venomous mammals. I aimed to explore sources for venom sequestration and the ecological function of slow loris venom, which has never been studied before. I examined the hypotheses that venom is used for intraspecific competition, predator defence and/or (ecto-) parasite avoidance. From April 2012 to June 2013 I observed 12 radio-collared and several uncollared wild Javan slow lorises (N. javanicus) at the rural agricultural field site Cipaganti in West Java, Indonesia. I collected behavioural observations including feeding and ranging data, examined faecal samples for diet remains and parasites, and regularly checked animals for ectoparasites. I also captured arthropods over five months. I monitored the coexistence with potential predator species using camera traps and by conducting forest surveys throughout Java. Venom may be sequestered from secondary plant metabolites and noxious arthropods, as the latter were abundant at the study site. Javan slow lorises fed extensively on gum (56 %) and 95 % of faecal samples contained arthropod remains. With regard to the ecological function, ranging patterns and social interactions indicated that the social system, with a monogamous social organisation and mating system with promiscuous tendencies, has potential for high sexual and non- sexual intraspecific competition. Camera trapping and forest surveys revealed the coexistence of Javan slow lorises with potential predators. However, predator avoidance could not explain the detected lunarphobia in Javan slow lorises. Additionally, animals were surprisingly ectoparasite-free. My results support all three hypotheses explaining the ecological function but should be enforced by analysing the venom composition in relation to various dietary and environmental factors, aided by (behavioural) experiments with potential predator and parasites. Finally, I applied my results to conservation of the Critically Endangered Javan slow loris, providing recommendations for the conservation of wild populations, husbandry of captive animals and reintroduction.