Aerial pursuit flights in the shoveler

Abstract

Analysis of 266 pursuit flights of wild birds provided a qualitative and quantitative description of aspects of this phenomenon. Flight behavior and frequency were analyzed for the general prelaying, laying, incubation, and renesting periods.Flight behavior of pursued males and females and that of the pursuing male varied little throughout the breeding season. No difference was detected on a daily basis.Flight frequency was greatest during the morning (0500 to 1000 h) period throughout the season. On a seasonal basis, frequency was greatest during territory establishment and declined after general incubation began. Another peak of activity occurred during the renesting period. Frequency during all periods reflected the number of non-territorial pairs interacting with territorial pairs.Attempted rape and associated flight was rare, with most flights apparently resulting from hostility associated with territorial defense. The pursuer was invariably a territorial male.The pursuit flight functioned in the establishment and maintenance of territories and was the major active mechanism in the spacing of breeding pairs.