Hapalemur alaotrensis Rumpler, 1975
English: Alaotran Gentle Lemur
French: Hapalémur du Lac Alaotra
German: Alaotra Halbmaki
Dutch: Alaotra Halfmaki
The total length of this gentle lemur is 77 to 81 cm. The upper parts are medium to darkish grey-brown. The underparts and face are slightly paler grey. The back of neck and top of head are brownish tinged. The head is somewhat more rounded and the fur is relatively longer, compared to H. griseus. Pelage colour of H. alaotrensis is similar to that of H. griseus but somewhat darker. Weights are approximately 1550 g for females and 1350 g for males. The females are to be 15 % heavier than the males.
H. alaotrensis occurs very locally - in contrast to Hapalemur griseus. At present, its distribution area is restricted to a small part of the semi-aquatic vegetation (the reed and papyrus beds) at the perimeter of the Lac Alaotra and the neighbouring marshes. Actually, the area of Lac Alaotra is very much reduced, because it has been desiccating during the last hundred years, similar as the other water bodies of the island. The depth is not more than 2.5 m, whereas it was still 8 m in the year 1900. In the south and the southwest it is bordered by some 75000 ha of swamps, which vegetation is regularly burned during the dry season (especially in September - October). Thus the future of its habitat is dark.
Recently the population has been estimated to be between 7.000 and 11.000 animals. More realistic is a figure of 7.500. This species is certainly declining and its numbers are probably very low.
Habitat and ecology
There have been only a few observations of this species in the reed beds around Lac Alaotra. Local fishermen reported that H. alaotrensis are most commonly sighted in small groups of three to four individuals in July, while a few months later, groups of around a dozen animals are seen; during February at the height of the wet season, as many as 30 - 40 individuals gather together. There is no bamboo in the region of Lac Alaotra, instead H. alaotrensis feeds on the leaves and the young shoots of the reed (Phragmites communis) and on the buds and pith of Papyrus (Cyperus madagascariensis).
This species is reported never to come to the ground, its usual mode of locomotion is vertical clinging and leaping. It is said to be able to swim very well, even females carrying infants on their backs can cross canals over 15 m wide. The Alaotran Gentle Lemur is most active in the morning and evening.
They give birth in January and February. Singletons are born and are carried on their mother's back from the moment of birth.
Hapalemur alaotrensis is particularly threatened by the burning of the reed beds that occurs every year. As well as having their habitat destroyed, the Gentle Lemurs are caught for food as they flee the fires, though Pollock, 1986a says they are not hunted directly. In addition, the lake is being drained for rice irrigation and both the papyrus and the reeds are cut for mats, fish traps, screens, barriers and fencing. This species is not found in any protected area.
A detailed ecological study and census of this species is recommended to determine its status and ecological requirements. It is suggested that translocation to a similar but better protected habitat is a possibility.
It is proposed that part of Lac Alaotra should be made into a reserve for the sake, particularly, of protecting H. alaotrensis and some of the aquatic birds which are also endemic to the area.