Unusual sleeping site selection by southern bamboo lemurs

Arboreal mouse lemurs discovered sleeping in a burrow on the ground

Finding sleeping sites is important for the fitness of many mammal species. Like most nonhuman primates, Madagascar's mouse lemurs (genus: Microcebus) are thought to exclusively use arboreal sleeping sites. The rufous mouse lemurs (Microcebus rufus) in Ranomafana National Park (southeastern Madagascar) have always been documented to sleep in either tree holes or leaf nests. However, in our recent field expedition, we observed, with the help of telemetry technologies, an unprecedented event of M. rufus sleeping in a burrow on the rainforest ground, curled up with a very slow heartbeat. Thus far, such behavior has not been observed in any other Microcebus species but is common in high-altitude dwarf lemurs (genus: Cheirogaleus), a closely related genus to the mouse lemurs. We believe that this discovery could illustrate an ecophysiological response strategy to habitat changes, which warrants further investigation.

Deciding Where to Sleep: Spatial Levels of Nesting Selection in Chimpanzees (Pan troglodytes) Living in Savanna at Issa, Tanzania

To understand how animals select resources we need to analyze selection at different spatial levels or scales in the habitat. We investigated which physical characteristics of trees (dimensions and structure, e.g., height, trunk diameter, number of branches) determined nesting selection by chimpanzees (Pan troglodytes) on two different spatial scales: individual nesting trees and nesting sites. We also examined whether individual tree selection explained the landscape pattern of nesting site selection. We compared the physical characteristics of actual (N = 132) and potential (N = 242) nesting trees in nesting sites (in 15 plots of 25 m × 25 m) and of all trees in actual and potential nesting sites (N = 763 in 30 plots of 25 m × 25 m). We collected data in May and June 2003 in Issa, a dry and open savanna habitat in Tanzania. Chimpanzees selected both the site they used for nesting in the landscape and the trees they used to build nests within a nesting site, demonstrating two levels of spatial selection in nesting. Site selection was stronger than individual tree selection. Tree height was the most important variable for both nesting site and tree selection in our study, suggesting that chimpanzees selected both safe sites and secure trees for sleeping.