CLUTTERED HABITATS REDUCE WING ASYMMETRY AND INCREASE FLIGHT PERFORMANCE IN EUROPEAN STARLINGS

Fluctuating asymmetry is a measure of developmental instability and re sults from both genomic and environmental influences. Levels of asymme try are (in part) influenced by mechanical constraints, as asymmetry i s believed to reduce efficiency. Here we have investigated the influen ce of habitat structure (''open'' and ''cluttered'' environments) on p rimary flight feather asymmetry and flight performance in European sta rlings. Our findings indicate that the increased flight demands of clu ttered habitats act to reduce primary asymmetry and increase flight pe rformance. These data are discussed in terms of the influence of asymm etry on flight performance and the mechanisms that give rise to asymme try. This study also presents a novel method, i.e., examining within-i ndividual changes in asymmetry, by which the detrimental and positive influence of the environment could be studied in subsequent field and laboratory studies without confounding environmental effects with geno mic influences.