Behaviour 2019
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Understanding the risk of infanticide in Shark Bay bottlenose dolphins
Diana C. Alvarado1, Molly H.F. McEntee2, Ewa Krzyszczyk2, Janet Mann2. 1826 S Loretta St., Rialto, CA, United States; 2Georgetown University, Washington, D.C., United States

Infanticide is documented in several delphinid species, particularly bottlenose dolphins. Despite 35 years of longitudinal data on bottlenose dolphins (Tursiops aduncus, Shark Bay, Australia) where males exhibit allied sexual coercion and aggression, evidence of infanticide is lacking. We propose that because this population is bisexually philopatric, females are protected from infanticide by males who are familiar with and related to local females and their offspring, albeit at some cost of inbreeding. Here, we investigate infanticide risk by examining adult male association with females throughout the calf period (N= 320 calves). Results show large predicted group sizes for newborn calves (< 3 months) with low male inclusion. We hypothesize that if local males serve as buffers against infanticide, then females may be largely avoiding unfamiliar males when calves are young and vulnerable. Understanding the risk of infanticide is necessary to understand female reproductive behavior and to determine whether socioecological strategies (e.g., polygamous mating, polyestrous cycling, and bisexual philopatry) actually counter the threat of male aggression and infanticide.