when morning comes, they take extented sunbaths high in the trees to bring their temperatures back up to normal. Remarkably, the females give birth at this time of year; nursing sifaka mothers produce very dilute milk and thus lose significant amounts of water during lactation. Nevertheless, these animals never descend to the ground to drink, seemingly able to balance their water budget by choosing plants high in liquid content and by occasionally licking dew from leaves and tree trunks in the early morning hours. Early morning is a time when members of the other group-living lemur species in Kirindy may take a breather from their efforts for a few hours, Red-fronted lemurs (Eulemur fulvus rufus), like other members of the genus Eulemur and the closely related bamboo, or gentle, lemurs (genus Hapalemur), have an unusual circadian rhythm, consisting of several bursts of activity irregularly distributed over the twenty-four-hour cycle. This type of activity pattern, which is termed cathemeral, has been reported outside Madagascar in only one other primate: Azara´s night monkey (Aotus azari) in South America. (More generally, among the tropical arboreal mammals of Africa, Asia, and South America, only sloths have such an on-again, off-again lifestyle.) Perhaps the cathemeral cycle of these lemurs represents an evolutionary midpoint in the transition from a nocturnal to a diurnal pattern; night vision requires increased sensitivity to light and generally comes at the expense of color vision and acuity. The transition to cathemeral activity may have been triggered by ecological changes associated with the extinction of large raptors and giant, probably diurnal, lemurs after the onset of human settlement in Madagascar about 2,000 years ago and the resultant hunting deforestation.