Abstract
The red slender loris (Loris tardigradus tardigradus) is endemic to Sri Lanka’s southern rainforests, where less than 2% of their habitat remains in small, fragmented patches. Because of continued encroachment on these small areas, the species is considered endangered. We present data on red slender loris abundance in nine of the last remaining forest patches in Sri Lanka’s Wet Zone and examine the relationship between habitat characteristics and abundance. Slender lorises were present at 7 out of 9 patches, and 44 animals were encountered. Density estimates ranged from 3.4 to 28 lorises/km2 with linear encounter rates of 0.1–1.1 lorises/km. Patch size heavily influenced encounter rate, with the largest patches containing more lorises. Removing the effect of patch size, we explored whether support size, undergrowth continuity, number of lianes/vines, and canopy continuity influenced loris density. We found slight evidence that increased numbers of lianes and vines were associated with decreased numbers of lorises. Although lorises rely on continuous substrates for movement, increased numbers of lianes and vines are also associated with the smallest and most disturbed habitats. In order to persist, red slender lorises require continuous forest. Unless forest encroachment can be halted and reforestation programmes started, their future in all but the largest of Sri Lanka’s remaining forest patches is bleak.
Resume
Le loris rouge (Loris tardigradus tardigradus) est endémique de la forêt pluviale du sud de Sri Lanka, où moins de 2% de son habitat subsiste sous forme de petits fragments isolés. Parce que ces fragments sont détruits continument, l’espèce est considérée en danger d’extinction. Nous présentons des estimations de l’abondance du loris rouge obtenues pour neuf des fragments de forêt subsistants dans la partie humide de Sri Lanka, et examinons les caractéristiques de ces habitats. Des loris ont été trouvés dans 7 fragments sur 9, et 44 animaux ont été rencontrés. La densité estimée était de 3.4 à 28 loris/km2, avec un taux de rencontre linéaire de 0.1 à 1.1 loris/km. La taille des fragments avait une très forte influence sur le taux de rencontre, avec davantage de loris rencontrés dans les plus grands fragments. Nous avons exploré les effets possibles de la taille des supports, de la continuité du sous-bois et de la canopée, et la présence de lianes, indépendamment de la taille des fragments. La densité de loris tendait à diminuer légèrement quand le nombre de lianes augmentait. Bien que les loris aient besoin de supports continus, la présence de nombreuses lianes est souvent observée dans les plus petits et les plus dégradés des fragments. Les loris ont besoin, pour subsister, de forêt continue. A moins que la destruction de la forêt ne cesse, et qu’un programme de reforestation soit initié, leur avenir dans les forêts de Sri Lanka est compromis, à l’exception des plus grands fragments.
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Acknowledgments
We thank Judith Masters and Carol Scheepers for organizing the International Congress on Prosimians and for inviting us to participate in this volume. We thank the Department of Forestry and the Department of Wildlife Conservation for research permits to carry out this study. We are grateful to the following individuals who assisted in the project: S. Wimalasuriya and G. de Silva Wijeyeratne for logistical aid and M. Abare, S. Gamage, E. Leavitt, Madumadarawa, Nallaka, and J. Stokes for assistance in the field. Funds for the project were provided by People’s Trust for Endangered Species, Columbus Zoological Park and Aquarium, Primate Action Fund of Conservation International, and Primate Conservation Inc.
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Nekaris, K.AI., Jaffe, S.M., Donati, G. (2012). Forest Fragmentation Imperils Red Slender Lorises (Loris tardigradus tardigradus) in South-Western Sri Lanka. In: Masters, J., Gamba, M., Génin, F. (eds) Leaping Ahead. Developments in Primatology: Progress and Prospects. Springer, New York, NY. https://doi.org/10.1007/978-1-4614-4511-1_10
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