Prenatal Cues of Predation Risk Modulate the Lasting Effects of Postnatal Predator Exposure in Gull Chicks.

AbstractPrenatal environmental cues can affect embryonic development to produce suitable phenotypes to match the expected conditions after birth. In gulls, parental alarm calls during incubation affect postnatal antipredator behavior, but how chicks integrate reliable prenatal and postnatal information and how this influences their development and viability remain unclear. In this study, we performed a match-mismatch experiment in which we manipulated acoustic cues of predator presence during embryonic development (adult alarm calls vs. colony noise) and the nestling period (simulated intrusions of a mink decoy triggering adult alarm calls vs. a rabbit decoy) in yellow-legged gulls. Our results show that embryonic exposure to predator cues alters the antipredator responses of chicks in early postnatal life, as indicated by increased tonic immobility. Chicks exposed to prenatal adult alarm calls also displayed faster crouching behavior but, unexpectedly, only in the absence of predators during the postnatal period. Chicks exposed to postnatal predator presence begged less during a standardized begging behavior test. The chicks experiencing mismatched prenatal and postnatal cues of predator presence showed smaller skeletal size and greater genomic damage at fledging compared with those developed in matched environments. Our results highlight the importance of the late embryonic stage in shaping phenotypic outcomes, depending on alignment with the postnatal environment.