Litter size, infant mortality and female body weight in captive black-and-white ruffed lemurs Varecia variegata

Abstract

We describe the development of selected life history traits (infant mortality, litter size) in a captive primate population and assess the role of resource abundance in observed changes in these traits. We studied patterns in the long-term development of litter size and infant mortality in the world captive population of Varecia variegata comprising 2186 ind. registered in the International Studbook and in the European Regional Studbook over a period of 40 yr. We also collected body weight data from 98 ruffed lemurs in 14 European zoos. Infant mortality increased significantly over the study period and from the founder to the F1 generation, with a mean litter size of 1.78 in the wild- born founder generation, compared to 2.14 for the zoo-born generations combined. A litter size of 4 had the highest rate of survival per litter. Female body weight, which we found to increase over the generations, had a significant positive correlation with litter size, but did not correlate with infant mortality. We suggest that changes in life history traits of a captive primate population, such as those in infant mortality and litter size of V. variegata, may be due to altered living conditions in captivity and that these changes may ultimately lead to a loss of genetic variability. High female body weight in captivity may indirectly contribute to changes in the demographic structure of a population. Our results suggest that management tools to control such developments need to be established for use in coordinated breeding programmes for endangered species.