Thalmann, U., Geissmann, T., Mutschler, T., and Rakotoarison, N. (1992). Field observations on a recently discovered population of Avahi in western Madagascar. In: Abstracts, Fourteenth Congress of the International Primatological Society, Strasbourg, France, August 16-21, 1992, p. 240, Strasbourg.

Field observations on a recently discovered population of Avahi in western Madagascar

U. Thalmann ¹; T. Geissmann ¹; T. Mutschler ¹ & N. Rakotoarison<sup>2

1</sup> Anthropological Institute, University Zürich-Irchel, Switzerland
² Lab. de Zoologie, Parc Botanique et Zoologique de Tsimbazaza, Antananarivo, Madagascar

In 1990, a new population of Avahi (Indridae) was found in the Reserve Naturelle Intégrale de Bemaraha in Western Madagascar which was recently classified as a World Heritage Landscape by UNESCO. The species was provisionally determined as Avahi cf. occidentalis. A short expedition was undertaken in 1991 to collect first field data on morphology, etho-ecology, and habitat of Avahi in Bemaraha. One animal was captured with a blowpipe and collared with an activity sensitive radiotransmitter. The group with the marked animal had four members. During the observation period (100 h) the animals were strictly nocturnal and showed an activity pattern with about three nightly peaks. The animals used a range of about 0.5 ha. Two frequently uttered types of vocalization have been recorded on tape, a third vocal signal only occurred twice. Pelage coloration differes between Avahi observed in Bemaraha and Avahi occidentalis from Ampijoroa (NW-Madagascar). At our study site a total of 9 different lemur species were observed. Local people said that Daubentonia also occurs in the region, but we failed to find them. The actual distribution range of Avahi is much larger than previously believed, although limits are not yet clear. A definite assessment of the taxonomic identity of the population from Bemaraha based on pelage coloration is not yet possible, because variation is not well known. Karyotype or DNA analyses may be necessary to solve this problem.

The project was supported by: A.H. Schultz-Foundation, anonymous donations, G. and A. Claraz-Donation, Leica Heerbrugg Ltd., Rentenanstalt, Swiss Academy for Science, Vontobel Holding, Zool. Soc. Zurich.