DEMOGRAPHY AND LIFE-HISTORY OF FREE-RANGING PROPITHECUS-DIADEMA-EDWARDSI IN RANOMAFANA-NATIONAL-PARK, MADAGASCAR

I conducted the first long-term study of the life history patterns of Propithecus diadema edwardsi-Milne-Edward's sifaka-in the rain forests of southeastern Madagascar beginning in 1986. I report behavioral observations on a total of 33 individuals from three groups over a 9-year span. We captured, marked, and released 21 individuals. Individual group size ranged from three to nine sifakas. Two breeding females lived in groups I and II until 1993. A newly formed group (III) had one breeding female. Age at first reproduction is 4 years for females and 5 years for males. Gestation length is 179 days (n = 2). Most births occurred in June (n = 17), but infants were also born in May (n = 2) and July (n = 2). Nine of 21 (43%) infants born died before the age of I year and 15 (67%) died before the age of reproduction. One female bred in her natal group after the death of the resident male and the immigration of an adult male. Another two females disappeared at 4 and 5 years of age; they could have emigrated or died. All 5-to-6-year-old males (n = 4) have emigrated from their natal groups to adjacent groups. Two have committed infanticide. Five or more individuals were killed by Cryptoprocta ferox. Despite high mortality and offspring dispersal, the number of individuals in the two main groups remained nearly the same over the 9-year study.