Home range, sleeping site use, and band fissioning in hamadryas baboons: Improved estimates using GPS collars.

Variation in spatial and temporal distribution of resources drives animal movement patterns. Links between ecology and behavior are particularly salient for the multilevel society of hamadryas baboons, in which social units cleave and coalesce over time in response to ecological factors. Here, we used data from GPS collars to estimate home range size and assess temporal patterns of sleeping site use in a band of hamadryas baboons in Awash National Park, Ethiopia. We used GPS data derived from 2 to 3 collared baboons over three 8-12-month collaring intervals to estimate annual and monthly home ranges using kernel density estimators (KDEs) and minimum convex polygons (MCPs). The 95% KDE home range was 64.11 km2 for Collaring Interval I (July 2015-March 2016), 85.52 km2 for Collaring Interval II (October 2016-October 2017), 76.43 km2 for Collaring Interval III (July 2018-May 2019), and 75.25 km2 across all three collaring intervals. MCP home ranges were 103.46 km2 for Collaring Interval I, 97.90 km2 for Collaring Interval II, 105.22 km2 for Collaring Interval III, and 129.33 km2 overall. Ninety-five percent KDE home range sizes did not differ across months, nor correlate with temperature or precipitation, but monthly MCP home ranges increased with monthly precipitation. Our data also revealed a southward home range shift over time and seven previously unknown sleeping sites, three of which were used more often during the wet season. Band cohesion was highest during dry months and lowest during wet months, with fissioning occurring more frequently at higher temperatures. One pair of collared individuals from Collaring Interval III spent 95% of nights together, suggesting they were members of the same clan. Our results both suggest that previous studies have underestimated the home range size of hamadryas baboons and highlight the benefits of remote data collection.

Contexts and consequences of takeovers in hamadryas baboons: Female parity, reproductive state, and observational evidence of pregnancy loss.

The evolutionary consequences of sexual selection and sexual conflict are epitomized in the hamadryas baboon, a species characterized by strong sexual dimorphism and intense male-male competition. Hamadryas males coerce individual females into reproductively exclusive one-male units via aggressive takeovers, and infants involved in such takeovers are at least four times more likely to be killed (or otherwise die) after takeovers compared to other times. Here we examine female reproductive state before and after takeovers to further investigate the determinants of takeovers and their impact on female reproduction. Our data set consists of 162 takeovers over a period of 20 years in a population of wild hamadryas baboons at Filoha, Ethiopia. Results show that, in contrast to their polygynandrous relatives, hamadryas males show no bias with regard to female reproductive state at the time of the takeover, but are more likely to take over nulliparous compared to multiparous females. In addition, these results reinforce previous findings demonstrating the high likelihood of infant loss after hamadryas takeovers and suggest that females may use an additional strategy of pregnancy termination to curtail investment in offspring that are very likely to die anyway. Thus, hamadryas males may target females with high future reproductive value and hamadryas females may employ counterstrategies to help mitigate the effects of sexual coercion and infanticide on their own fitness.