Researchers studying the endangered population of the Milne-Edwards’ sifaka, a lemur found in south-eastern Madagascar, have found that the females can live for up to twice as long as their male counterparts.
While females tend to outlive males in many animals, including humans, the Milne-Edwards’ sifaka — a rainforest-dweller with orange-red eyes, a black face and woolly dark brown fur — does not seem to differ in any of the ways thought to give other female animals a survival advantage. Both sexes have similar levels of testosterone, and are equally likely to pick fights, explained lead author Stacey Tecot (University of Arizona); they also grow at similar rates, reach the same size and stray from the safety of their social groups.
After observing these animals for more than two decades in the wild, Patricia Wright (Director at the Institute for the Conservation of Tropical Environments) and her colleagues analysed the detailed records of births, deaths, and dispersal behaviour of more than 70 individual lemurs. While both males and females dispersed equally frequently, and wandered just as far, females generally stopped dispersing after reaching 11 years old. The males continued to disperse to older ages, which could carry greater costs, as the older animals are not as agile or quick to heal from injury.
Read more at Stony Brook University