Maternal condition and offspring sex ratio in a group of free- ranging rhesus monkeys: an eleven-year study

Significant differences among lineages of Macaca mulatta on Caya Santiago, Puerto Rico, resulted from a strong tendency for middle-lineage females to produce biased proportions of daughters, but overall maternal condition does not appear to be a probable explanation for variations in sex ratio in this group. Random variation or a genetic predisposition in the middle lineage to produce daughters, along with a general tendency for shorter interbirth intervals following the birth of viable daughters than sons, may account for the differences in neonatality. -from Author