Ecological Drivers of Breeding Peak in Hamadryas Baboons (Papio hamadryas) Across Two Contrasting Habitats in Saudi Arabia

Abstract

Reproduction could be the most important control point for the spread of hamadryas baboons (Papio hamadryas). Understanding the drivers of reproduction is necessary to determine which interventions may work best, in which locations, and at what time of year. We analyzed monthly variation in the proportion of estrous females and black infants in two troops inhabiting two different sites (Dam and Al Hada) in Saudi Arabia over the course of one year (one week per month; ~720 h per site-year; non-contemporaneous). The effects of season, rainfall, natural food diversity, and anthropogenic foods were studied using generalized linear models with additive nonlinear terms. At the hotter and drier Dam site, seasonality explained most variation, with a higher proportion of estrous females observed during the hot season. At the cooler and wetter Al Hada site, infant proportions and estrous females responded nonlinearly to rainfall, natural food diversity, and human food subsidies, with less seasonality. Patterns in the proportion of infants broadly aligned with the estrous data and provided insight into the temporal distribution of births across the two troops. The two-troop contrast in this study suggests reproductive flexibility. Specifically, there may be a dual control system with an intrinsic seasonal control modulated by a flexible ecological response. Further work is needed to understand the scales and conditioning of environmental drivers of baboon reproduction to inform wildlife management.