Sahamalaza Sportive Lemur (Lepilemur sahamalazensis)

Mohamed bin Zayed Species project number 13255890

To date, not much is known about the biology and ecology of sportive lemurs in general; data on the social organisation, habitat preferences, home range size and anti-predator behaviour is available for only four out of the 26 named species. Many species of Lepilemur occur only in single locations and, as arboreal species, are dependent on undisturbed forests for their survival (Craul et al., 2009; Seiler, 2012), which makes them highly vulnerable to human-caused disturbances. In addition, increased unsustainable hunting diminishes population numbers even faster (Schwitzer et al. 2006). Since July 2012 all 26 sportive lemur species have either been classified as Vulnerable, Endangered or Critically Endangered by the IUCN (C. Schwitzer, pers. comm.).

One of the species classified as Critically Endangered is the Sahamalaza sportive lemur (Lepilemur sahamalazensis). The Sahamalaza sportive lemur is confirmed only for a single location in Madagascar, the Sahamalaza Peninsula. Taking in consideration the habitat quality and structure of the forest patches in its range, a remaining population of about 3000 individuals was estimated, making this one of the most endangered species of lemur (Ruperti, 2007). Recent studies investigating the habitat requirements found that Sahamalaza sportive lemurs are highly depended on factors such as tree density, canopy cover, crown diameter and abundance of sleeping sites and occur nearly exclusively in primary forests (Ruperti, 2007; Seiler 2012). Severe destruction of habitat is likely to cause a significant decline in population numbers as the range of this species is very limited.

Considering these issues the Sahamalaza sportive lemur has gained remarkably little scientific attention so far. This project adds to the body of acquired knowledge by collecting data on the social organisation of the Sahamalaza sportive lemur. From preliminary observations, – sleeping alone during the day, rare social encounters during activity phases, interactions being mainly agonistic – it was assumed that this species is solitary. In contrast to other Lepilemur species, the Sahamalaza sportive lemur may thus be the first entirely solitary species of Lepilemur.

L. sahamalazensis inhabit relatively small home ranges (~0.5 ha) (Seiler, 2012), but data on differences between the sexes and on whether or not home ranges overlap are missing. Obtaining these data is a necessary step towards concluding the social system of the Sahamalaza sportive lemur.

Taking in consideration the potentially energy-saving behaviour necessary due to the low-energy diet of this species, and the preliminary observations of social interactions, we hypothesised that the Sahamalaza sportive lemur lives solitary with no pronounced pair bonds.

 

To determine whether this species is truly solitary this study aimed:

(1) To investigate the size of the home ranges of males and females and compare them. Additionally the degree of overlap will be calculated.

(2) To examine the level of gregariousness displayed both during the day and the activity phase at night.

 

By combining these factors, we aimed to infer the social organisation of the Sahamalaza sportive lemur.

The information gained through this study will be used as a basis for further projects involving research of the ecology and behaviour of this Critically Endangered species.