Distribution, population size and morphometrics of the giant-striped mongoose Galidictis grandidieri Wozencraft 1986 in the sub-arid zone of south-western Madagascar

Abstract

Galidictis grandidieri (Wozencraft 1986) is a nocturnal carnivoran endemic to the threatened spiny forest ecosystem of the Mahafaly Plateau in southern Madagascar. Previous investigations estimated a total population size of about 3000 individuals restricted to an area of 440 km2, making it one of the geographically most limited and rarest mammalian carnivoran species worldwide. Given the increasing threat through habitat destruction we compiled additional morphometric measurements and investigated the distribution and abundance of the species, using grid and transect captures. G. grandidieri were larger than indicated by previous samples and showed significant sexual dimorphism with a mean body mass of 1640 g for males and 1400 g for females (overall mean: 1500 g). The highest densities were found in the littoral forest at the western edge of the Mahafaly Plateau (six to eight individuals/km2). From there, its abundance declined exponentially towards the east. The distribution of G. grandidieri is probably determined by decreasing water accessibility away from the cliff. We estimate a total distribution area of about 1500 km2 and a total population size between 3115 and 4995 animals. Based on these estimates, G. grandidieri occurs in a much larger area than assumed so far, but reaches lower densities.