'Nursery nests' are better for survival of young black-and-white ruffed lemurs

Aug 06, 2013
Black-and-white ruffed lemur (Varecia variegata variegata) in a tree. Credit: TONY CAMACHO/SCIENCE PHOTO LIBRARY

Young Malagasy black-and-white ruffed lemurs are more likely to survive when they are raised in communal crèches or "nursery nests" in which their mothers share the draining responsibility of feeding and caring for their offspring. This is according to anthropological research on lemur infant care by Andrea Baden and colleagues of Yale University. The study, published in Springer's journal Behavioral Ecology and Sociobiology, describes a rare case in which fitness differences, such as infant survival, between cooperative and non-cooperative lemurs are observed.

Baden and her team studied eight female black-and-white ruffed lemurs (Varecia variegata) in the Ranomafana National Park in Madagascar who only once reproduced large litters during the six consecutive years of observation. Combined data on their nesting behavior, and the survival of infants showed a positive relationship between crèche-use, a mother's time spent feeding and infant survival.

Ruffed lemurs are large-bodied and gregarious primates with slow life histories that form social communities to cooperatively help defend territory. They are the only diurnal non-human primates who bear litters of altricial or undeveloped offspring. This means that, as in humans, newborn ruffed lemurs need special care and feeding. Newborns, for instance, cannot yet cling to their mothers at birth, which makes travel together in the impossible. This places a specific energy burden on the mother, who provides exclusive care for the first six weeks of her infants' lives and therefore has less time to spend on feeding and foraging.

Only a small percentage of female ruffed lemurs opt for solitary brooding and raise their young on their own. The others participate in communal nesting, breeding and babysitting in which several mothers regularly pool resources to cooperatively rear their offspring until they are about 10 weeks of age and are capable of independent travel. This method of infant care is unusual in mammals, and especially among primates, with the most notable exceptions being humans and some nocturnal primates of the suborder Strepsirrhini.

Communal nesting allowed female ruffed to spend less time at their nests and gave them more opportunity to feed elsewhere than was possible for single nesting females. Infant survival was also significantly higher the more this crèche system was used. Genetic tests showed that cooperation was common among kin, but not exclusively so. This is the same as with humans and several other communally breeding birds and mammals.

"Kinship may have helped the evolution of cooperative breeding in primates, but the mutual benefits may outweigh the costs of helping, irrespective of any family relationships," says Baden, who believes that the current research sheds light on understanding just how communal breeding evolved. "Our results contribute to a growing body of evidence suggesting that kin selection alone cannot explain the extensive cooperation observed in many animal taxa."

Explore further: China bans ivory carving imports for one year

More information: Baden A.L., et al. (2013). Communal nesting, kinship, and maternal success in a social primate, Behavioral Ecology and Sociobiology. DOI: 10.1007/s00265-013-1601-y

add to favorites email to friend print save as pdf

Related Stories

Mother's little helpers let her relax

Oct 24, 2012

Having relations around to help look after the kids lets mothers ease off and save energy for the next lot, a study of Australian cooperative birds shows.

Recommended for you

China bans ivory carving imports for one year

4 hours ago

Beijing has imposed a one-year ban on the import of ivory carvings, amid international criticism that rapidly-growing Chinese demand could push wild African elephants to extinction within a generation.

Forest tree seeds stored in the Svalbard seed vault

21 hours ago

A new method for the conservation of the genetic diversity of forest trees will see its launch on 26 February 2015, as forest tree seeds are for the first time stored in the Svalbard Global Seed Vault on the Spitsbergen Island, ...

Baby sea turtles starved of oxygen by beach microbes

22 hours ago

On a small stretch of beach at Ostional in Costa Rica, hundreds of thousands of sea turtles nest simultaneously in events known as arribadas. Because there are so many eggs in the sand, nesting females freque ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.