Flying consumes lot of energy. Feathers, being the tools of the flight, have pivotal role in birds' energy consumption. Recent research showed that even minor injuries in feather structure may greatly increase energetic costs of flying. Thus, the quality of feathers should be important for birds, and it is expected to influence reproductive decisions.
We used field observations to investigate whether the quality of primary wing feathers of house sparrows are related to the start of breeding and the number of eggs laid. We used digital photographs to measure the quality of feathers. Publication in preparation.