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 obs ervations on a total of 33 individuals from three groups over a 9-year span. We captured, marked, and released 21 individuals. Individual gr oup 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 bre eding female. Age at first reproduction is 4 years for females and 5 y ears for males. Gestation length is 179 days (n = 2). Most births occu rred in June (n = 17), but infants were also born in May (n = 2) and J uly (n = 2). Nine of 21 (43%) infants born died before the age of I ye ar and 15 (67%) died before the age of reproduction. One female bred i n her natal group after the death of the resident male and the immigra tion of an adult male. Another two females disappeared at 4 and 5 year s 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. Tw o have committed infanticide. Five or more individuals were killed by Cryptoprocta ferox. Despite high mortality and offspring dispersal, th e number of individuals in the two main groups remained nearly the sam e over the 9-year study.