Maternal tactics for mitigating neonate predation risk during the postpartum period in Thomson’s gazelle

Abstract

The time immediately following birth is a period of high predation risk for ungulate neonates. Ungulate mothers exhibit perinatal behaviors that appear to mitigate offspring risk during this time. However, few studies of infant mortality include the postpartum period. Therefore, the function and effectiveness of these maternal behaviors are untested. We observed perinatal behavior in 11 Thomson’s gazelle (Eudorcas thomsonii) mother-infant pairs in a free-ranging population under predation pressure. Five of the six fawns that were detected by predators during the perinatal period were killed. Fawn survival therefore depended on avoiding detection by predators. Considered individually, neither prepartum isolation from conspecifics nor birth site selection affected the risk of being detected by a predator. However, analyses revealed two distinct perinatal tactics: mothers either isolated and gave birth in tall grass or remained in their social groups and gave birth in short grass. Both of these tactics resulted in lower risk of predator detection compared to behavior that was inconsistent with either tactic. The tactics represent a maternal trade-off between minimizing the duration of the highly vulnerable postpartum period and minimizing conspicuousness to predators.