Life in Unpredictable Environments: First Investigation of the Natural History of Microcebus griseorufus

The dry spiny forest of southern Madagascar is a highly unpredictable environment in terms of the amount and distribution of rainfall. The region is also subject to marked El Niño oscillations. One of the inhabitants of the region is Microcebus griseorufus (Kollman, 1910), the reddish-grey mouse lemur. During the 4 yr of the study, the focal population underwent marked fluctuations in size and exhibited a relatively long reproductive season: September–May. Subjects used daily torpor and expressed opportunistic seasonal fattening when food availability was high. They fed mainly on gum, especially during periods of drought. The estimated sex-ratio of the population is 54% female. Young males dispersed. Females and less frequently, males, associated in same-sex pairs that sometimes joined to form larger sleeping groups. I observed both erratic and resident males, the latter sometimes associated with females in sleeping groups. Mating occurred from September to January and involved mate-guarding. Individual female home ranges (N?=?14) overlapped with, on average, 2.8?±?0.3 male home ranges (range 2–5), whereas individual male home ranges (N?=?12) overlapped with 4.7?±?0.4 female home ranges (range 2–7). Female estrus was not synchronized, even within the female pairs, allowing alloparental care. Gestation lasted 52 d in 1 female, and litter size could be as high as 3; 20 reproductive females out of 37 adult females raised only 1 or 2 young per year.