In the extreme south of Madagascar,  Lemur catta regularly utilize the introduced cactus species, Opuntia ficus indica and Opuntia stricta. This finding is significant as the habitat of this region, which is comprised of these cactus species as well as xerophytic Didiereaceae-Euphorbiaceae forest , represents over 90% of this species' potential range. Moreover, the use of cacti as a primary ecotone for a primate species has never before been documented. Finally,  it appears that nearly all of the remaining forests in this region are protected because they contain tombs, and that many of these forests have remained stable for over 50 years as sacred sites.
         I have recently spent 15 months studying  two troops of  L. catta in the extreme south investigating four primary research questions: (a) How does the behavioral ecology of  the cactus adapted L. catta compare with gallery forest L. catta? (b) Are there any indications that these cactus dwellers suffer in health, nutrition, and reproduction? (c) How important is Opuntia as a dietary resource for these individuals? (d) What is the daily interaction between these lemurs and the local villagers? Behavioral observations, ranging data, health assessments, and nutritional analyses were used to addresse these questions.
        The results of this study are in the process of being analyzed.  However, some notable observations are worth mentioning here. First, two males are known to have ranged for a minimum of 6 km before they integrated into one of the troops. Moreover, these same two males were observed within  the region's reserve, Cap Sainte-Marie, prior to finding the troop. Ironically, it is believed they were there to feed upon the Opuntia that the forestry management ministry (ANGAP) is working so hard to eradicate. Second, with the exception of the Opuntia fruit, nearly all of the vegetation consumed by both troops are endemic and abundant. Seventy varieties of plants observed to have been eaten by the ring-tailed lemurs were collected for the nutritional analyses. Third, despite all of the taboos associated with human activity within sacred forests, these sites did not seem to be places of refuge for the lemurs. In fact, the few aggressive encounters by humans towards the lemurs that I observed occurred at these sites. Fourth, both troops used the Opuntia hedges as their only sleeping sites and as places for refuge when they were spooked. Similarly, the Opuntia hedges were used frequently during the day when it was rainy and cold. The fruits of this plant were consumed throughout the year. One troop fed upon the Opuntia almost exclusively several months of the year.