populations are isolated (Sussman et al., 2003). Densities are somewhat higher in the remaining scattered gallery forest areas. The southernmost population of L. catta occurs in the region of Cap Ste. Marie, on the very southern tip of Madagascar. Little is known about this population, but Sussman et al. note that it may be seasonally mobile, as ring-tailed lemurs were observed feeding on seasonal fruits around the Cap Ste. Marie Reserve in October of 2001 and 2002 by a forestry worker, but they are not found there at other times of the year. Four Kilometers from the reserve, they have been seen on a more regular basis (Kelley, personal communication). The habitat in this area is a combination of crops, sacred forests, and introduced Opuntia cacti, and the lemurs have been observed most often in the Opuntia hedges (Kelley, personal communication).
Moving eastward along the south coast, much of the original natural vegetation was cut before 1950 for both crops and sisal plantations, which now dominate this area. Only a few small patches of gallery forest remain, including Berenty Private Reserve. Throughout this area, Sussman et al. (2003) note the existence of small circular patches of vegetation, which have not changed since at least 1950. These are sacred forests, and some contain lemurs; however, no lemurs exist in the surrounding agricultural areas. In the Andohahela Reserve near the south coast, L. catta live both in disturbed dry forest at low densities, and in higher numbers in the gallery forest areas (Raharivololona and Ranaivosoa, 2000). Their southeastern limit occurs at the border of the eastern and western watersheds, with populations living both dry and gallery forests. They have been spotted at Petriky near Tolagnaro (Goodman et al., 2006) and in littoral forest south of Tolagnaro (Sussman et al., 2003).
A high-altitude population of L. catta was discovered in the mid-1990s inhabiting an area of the Andringitra mountain range near the eastern edge of its range. This population has been studied by Goodman and Langrand (1996), Goodman and Rasolonandrasana (2001), and Rakotoarisoa (2000), and described genetically by Yoder et al. (2000). These ring-tailed lemurs live in the coldest locality on Madagascar, with nightly temperatures falling to -16°C, but reaching up to 30-35°C during the day. Here, L. catta groups live between 900 and 2600 m, well above the end of the tree line at 1950 m (Goodman and Langrand, 1996; Goodman et al., 2006; Rakotoarisoa, 2000). Andringitra L. catta exhibit somewhat different pelage coloration from other populations but they are not a subspecies (Yoder et al., 1999, 2000). They have a thicker coat, suggested to be an adaptation to extremely low temperatures, and lighter pelage color, which may result from exposure to intensive solar radiation in their environment. The diet and ranging pattern of this population will be discussed later in the chapter.
In Madagascar's southwest, L. catta occurs at very low densities in the remaining areas of the coastal Mikea Forest, and Sussman et al. (2003) note that even before massive cutting of this forest occurred, low densities were recorded, but with the disappearance of habitat in this area, the few remaining populations are now extremely isolated. In the Zombitse forest, between Toliara and Isalo, few L. catta exist. The forest here is drier than the gallery forests in the southwest, and does not support tamarind trees, which L. catta rely upon in gallery forest habitats.
In the Lake Tsimanampetsotsa region near Toliara (very close to the western coastal area), L. catta groups are found in government-protected areas or sacred forests in these regions. Inland, much of the natural dry-adapted vegetation in the Mahafaly Plateau region has been cleared for swidden and subsistence agriculture, although Sussman et al. (2003) found ring-tailed lemur populations to varying degrees in remaining riverine forest areas, and well-protected populations exist at the Beza Mahafaly Special Reserve near Betioky-Sud and at Isalo National Park. Sacred forests also exist in the Beza Mahafaly region, which have been maintained over time, and are inhabited by ring-tailed lemur groups (Sauther, Gould, and Whitelaw, personal observation).
The question of adaptation to extremely arid environments has been discussed by Goodman et al. (2006). They note that the presence of water sources could be a limiting factor in the distribution of this species; however, ring-tailed lemur vocalizations have been heard in an area of Kirindy-Mitea National Park in the west where no permanent water source exists. Goodman et al. suggest that they obtain water in this area by licking dew in the early morning and from the water content in some of their food plants. Similarly in and around the Beza Mahafaly Reserve, the home ranges of some groups do not include any freshwater source, yet some of these groups are very large, and in the dry season, no group has access to fresh water because the riverbed is dry. Thus, dew and moisture from food sources in the dry season, and water cachement areas in the wet season can sustain such groups. L. catta inhabiting spiny forest must cope with as little as 30-50 cm of annual rainfall, and must obtain water from dew and succulent plants, including Aloe (Jolly, 2003).
Goodman et al. (2006) emphasize that because ring-tailed lemurs are a semi-terrestrial species (degree of terrestriality averages 30% [Jolly, 1966; Sussman, 1972, 1977] and ranges from 3 to 75% depending upon season [Sauther, 2002]), they are able to disperse across nonforested areas, and across riverbeds in the dry season, and therefore their geographic range is not constrained by river systems. Nonetheless, the overall population of this species has decreased significantly in the past 50 years due to deforestation (Sussman et al., 2003).
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