Moonlight influence on quality of nestlings of scops owls depends on paternal coloration

The moon might favour the maintenance of colour polymorphism via disruptive selection if the different colour variants performed differently in terms of prey capture under different moonlight levels. Moonlight, however, may affect prey capture as a by side effect of its influence on prey behaviours. Here we combine data of parental provisioning and owlets' quality with one ex-situ study of grasshoppers' activity to test whether Eurasian scops owls (Otus scops) with different plumage colour and their prey are differently affected by moonlight. Food provisioning increased from new- to full-moon. However, the effect of moonlight on owlet mass gain and immune response depended on paternal coloration. On the one hand, body mass gain of nestlings of the greyest fathers increased from nights with new- to full-moon, whereas it did not change with moonlight for the brownest fathers. On the other hand, PHA response of nestlings of the brownest fathers increased with high moonlight levels during t...