Department of Anthropology, Portland State University, Portland, OR 97207
Saturday 1:45-2:00, Grand Ballroom II
Few primates give birth to litters or build nests in which to care for them. Those that do are small-bodied, nocturnal and solitary. There is one enigmatic exception. Variegated lemurs (Varecia) are large, day-active, gregarious primates that bear litters in arboreal nests. Furthermore, they raise their young cooperatively and practice absentee parenting (infant stashing combined with oral transport of young). Till recently we lacked quantitative records of infant care. Observations, supplemented by canopy-level photography, were made in one population of Varecia rubra on the Masoala Peninsula, Madagascar. Data were collected on three litters and all care-givers during the first three months after birth (November 2010 - January 2011). Focal litter sampling determined which individuals provide care, how often, and of what type. Types of infant care of long duration were recorded at 5-minute time point intervals providing time budgets (e.g., guarding), while those of short duration were recorded on an all occurrence basis to obtain raw frequencies and hourly rates (e.g., infant transport). Simultaneously, focal mother sampling produced a record of maternal absence and activity when not in contact with young. Results demonstrate that litters benefit from costly forms of alloparental care, though rates and frequencies vary across helper age-sex classes. Furthermore, the total number of helpers varied enormously between litters; from one to over five. Four co-adapted traits appear to underlay the variegated lemur’s ability to raise litters of non-clinging young while simultaneously relying on a patchily-distributed diet of ripe fruit: long-distance foraging, fission-fusion sociality, absentee parenting, and alloparenting.
The National Geographic Society-Waitt Foundation and a Faculty Enhancement Grant from Portland State University provided support for this research.