Group size, composition and stability in a wild population of blue-eyed black lemurs (Eulemur flavifrons) at Ankarafa, Sahamalaza National Park

Abstract

Four groups of blue-eyed black lemurs ( Eulemur flavifrons ) were under continuous observation over a 3-year period. Data on group composition and dynamics were regularly recorded. Groups were multimale, multifemale ranging in size from six to eleven individuals, including three to seven adults. The number of resident individuals (those remaining in the same social group for the duration of the study) varied between groups, but any given group never contained more than three adult females. Both male and female migrations occurred, but only males were seen immigrating to a foreign social group. Sex ratio at birth varied strongly between years and could be male biased.