Bacteria in starling nests

We investigated the bacterial frequency and identified 11 genera of bacteria in starling-nests of a nest box colony in southern Germany. We sampled bacteria with a new method: agar paddles, developed for the food industry, were pressed against the naked belly of nestlings at an age of 14 days for 5 seconds. The bacteria colonies on the paddle surface were counted after incubation and their numbers served as an estimate of bacterial infestation of a nest. Bacteria numbers increased with season and precipitation. No relationship between bacteria load of the nests and hatching and fledging success, nestling mortality and body mass close to fledging was detected. The reason for this may be that a high bacteria load is not necessarily harmful but may even act in a beneficial way on the digestive and immune system. Nevertheless we consider it possible that the higher load of bacteria of late nests may under certain conditions be one of the factors responsible for the frequently observed lower quality of second brood nestlings.