Social structure of the solitary slow loris Nycticebus coucang (Lorisidae)

Abstract

The social structure and social interactions of the nocturnal slow loris Nycticebus coucang are described from locational as well as observational data on wild animals. Data were collected during 600 h of nocturnal radio-tracking and 400 h spent radio-locating sleeping slow lorises during the day. Data are also presented on morphometrics, injuries and ectoparasites, and dispersal. The slow loris is generally described as solitary, but although closerange encounters were rare, animals were observed to form stable social units ('spatial groups') characterized by home-range overlap and friendly interactions among members and non-overlap between units. Four spatial groups were observed, each consisting of a single adult female, a single adult male and a varying number of younger individuals. Group composition, together with relatively small testis volume and natal dispersal occurring in both sexes, hints towards a monogamous mating system. One extended family group was formed by the delayed dispersal of a primary pair's offspring. We did not find another often quoted correlate of monogamy -a weak sexual size dimorphism. Friendly interactions among members of a spatial group included allogrooming, following, alternate click-calls, and sleeping in contact. Yet, members did not engage in any co-operative behaviour of the types usually thought to be responsible for group formation in gregarious mammals. One important factor contributing to the sharing of space between slow lorises is probably that chances of successful dispersal are low. However, subtle benefits arising from the presence of conspecifics (allogrooming, transfer of information on food resources) may also be crucial for the formation or maintenance of slow loris spatial groups.

Chronic intake of fermented floral nectar by wild treeshrews

“…Trapping, tracking, and observation techniques have been described (38). We captured 11 life pentailed treeshrews and 33 life slow lorises.…”

Living together in the night: abundance and habitat use of sympatric and allopatric populations of slow lorises and tarsiers

“…Lorises appear to lack a defined microhabitat, as differences between loris plots and control plots were not significant. Past studies on slow lorises have found that they occupy numerous types of environment, from plantations and other agricultural areas to heavily degraded forests and pristine forests (Elliot & Elliot 1967, Wiens & Zitzmann 2003, Radhakrishna et al 2006). An important limitation for lorises is that they are quadrupedal and are incapable of leaping, thus requiring canopy continuity to move easily throughout the forests, although they can move on Merker et al 2005).…”

“…In our study we observed an average height of 1.8 m (range 0 to 20 m). Slow lorises occupied heights that ranged from the ground to as high as 30+ m (Wiens & Zitzmann 2003, Nekaris & Bearder 2007, but until now almost all studies have been conducted on species that do not share height ranges with tarsiers. The median height of trees used by Bornean lorises was 15 m, with a range of 8.5 to 30 m. The Bornean loris range overlaps the range of the tarsiers, but only by 1.5 m. Compared with other Nycticebus spp., the Bornean lorises do significantly favor higher canopy levels.…”

“…Bornean slow lorises N. menagensis have even been observed attempting to predate on tarsiers (Niemitz 1979). Some argue that because tarsiers are strict undergrowth foragers, most competition is avoided (Niemitz 1984, Crompton & Andau 1987, but all slow loris species forage at all levels of the forest (Wiens & Zitzmann 2003, Pliosoengeon & Savini 2008, suggesting an absence of spatial niche separation.…”

Spatial Patterns and Dynamic Interactions Among Raccoons in Eastern Kansas

“…Solitary species often occupy habitats with dense vegetative cover, are nocturnal and secretive, and consequently are difficult to observe (Gittleman 1989;Wiens and Zitzmann 2003). These difficulties historically have limited the study of social behavior to more gregarious species (Cooper and Randall 2007;Gittleman 1989).…”