Heterospecific egg destruction by Wattled Starlings and the impact on Pied Babbler reproductive success

While egg destruction by brood parasites is a relatively well-known phenomenon, such destruction by non-brood-parasitic heterospecifics is less common. Here, we provide the first evidence of egg destruction by Wattled Starlings Creatophora cinerea on Pied Babblers Turdoides bicolor. We find that the incubation success of Pied Babblers decreases significantly following the arrival of Wattled Starlings at the study site, and we provide video evidence of Wattled Starlings destroying Pied Babbler eggs. This behaviour is costly to Pied Babblers, whose current reproductive attempt is abandoned, with subsequent reproductive attempts delayed by several weeks. We found no evidence that egg destruction occurred for nutritional benefit: Wattled Starlings never consumed the eggs they destroyed. Rather, this behaviour appears to represent a form of resource competition, since Wattled Starlings only predate babbler nests in habitats where the starlings also build their nests.