Nest material preferences by spotless starlings

The avian nest is an essential structure for offspring development. For adults, nest building entails costs in terms of time, energy and exposure to predators and parasites. Amount and diversity of materials used for nest building depend on their availability and functionality in scenarios of sexual selection and parasitism. Green plants and feathers of different colors have been hypothesized to play key roles in offspring protection against pathogens, and we here experimentally assessed spotless starling (Sturnus unicolor) preferences for pigmented vs. unpigmented feathers and for different green plants (aromatic vs. non-aromatic plants) as nest materials. We predicted a preferential selection of unpigmented feathers and aromatic plants according to the antimicrobial properties of these materials described in the literature. We evaluated these predictions during nest building and during egg-laying stages. As expected, starlings preferentially selected unpigmented feathers both before a...