Female Spotless Starlings (Sturnus unicolor) remove green plants from their nests

The males of the European Starling (Sturnus vulgaris) and Spotless Starling (S. unicolor) carry green plants to their nests. However, the consequences of this behaviour for the females are still poorly known. In this study, we evaluated the behavioural responses of female Spotless Starlings to the green plants that they find in their nests. We added green plants to a group of experimental nests (E nests) and quantified the activity of the nesting females in the E nests and in a group of non-manipulated nests (C nests). The females never added green plants to their nests, but they removed the green plants more frequently from the E nests than from the C nests. The number of departures from the nest by females that carried green plants was positively correlated with the number of visits by females that carried nothing. In contrast, the number of departures by females carrying green plants was uncorrelated with the number of visits made by females that carried nest-building materials. These results suggest that the females made a specific additional effort to remove the green plants from the E nests. We propose that this behaviour may be an adaptive response of mated females that serves to counteract the eventual negative effects of green plants on their reproductive success. However, competing hypotheses cannot be rejected, and additional work is needed to better understand the removal of green plants by female Spotless Starlings.