Social organisation, ecology and conservation of loris tardigradus tardigradus (lorisformes; primates)
Loris tardigradus tardigradus, the red slender loris, is a small nocturnal primate inhabiting the rainforests of Sri Lanka. This study provides new information on the natural history, social organisation and ecology of this endangered strepsirrhine, from which conservation action plans are derived. The study was conducted in Masmullakele, a 290ha forest reserve. Vegetation, diurnal and nocturnal surveys were conducted between October 2004 to August 2005 and the radio-tracking study from August 2005 to July 2006. Seventeen lorises were radio-tracked for 339 nights, and observed for 579hrs. Average home range size was 3.2ha ± 1.7, and core area size 2.2ha ± 1.1 with no significant inter- or intra-sexual differences. Overlap was significantly higher inter-sexually than intra-sexually. Lorises formed spatial pairs with coinciding home ranges and little overlap with neighbouring animals and had high indices of territoriality. Lorises were social 21.4% of the time, with neutral interactions being the most frequent, and direct negative interactions the least. 'Paired' lorises had a significantly higher degree of cohesiveness and sociality than unpaired lorises. Lorises did not use anthropogenically disturbed habitats and preferred interior forest, although they used patch perimeter habitat (forest edge microhabitat) significantly more than was available. Temperature had a significant positive effect on activity, whilst a significant negative correlation was found between rainfall and home range size. There was indication that lorises may have had two breeding seasons in that year based on time of oestrous and births, and changes in ranging patterns. Lorises have a complex social organisation. The spatial system is unimale-unifemale, and the social system, gregarious or dispersed depending on degree of spatial overlap. The mating system does not appear to be monogamous. Possible mating systems are: 1) serial monogamy; 2) long-term pair-bond with the occurrence of EPCs; 3) formation of social and spatial pair but with a polygynous mating system. Conservation actions proposed are to: increase baseline data on L. t. tardigradus across the Wet Zone, continue this study's research objectives, conduct process-based models, decrease fragmentation within small forests and create a network of protected forests.
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