Behavior of Common Swift Apus apus and House Martin Delichon urbicum towards a flying dummy

We tested for airborne epimeletic (care-giving) behaviour in Common Swift Apus apus towards young swifts during their first flight. Tests were performed where colonies of Common Swift and Western House Martin Delichon urbicum co-occur. Three variants of a flying dummy were used; two with pointed wings of which one entirely black (1) and one with partly white body (2). The third was black with broad wings (3). Reactions were documented on film. Swifts and martins had opposite reactions to dummies 1 and 2. As we anticipated, martins seemed supportive in a test with dummy 2 and seemed to “guide” the dummy epimeletically. However, a swift approached dummy 2 in a support-like attempt, but deviated after a close look. In a test with dummy 3, swifts acted highly hostilely. We discuss reasons for these outcomes and the importance of dummy appearance. We illustrate the flight paths of the dummy, swifts and martins with trajectories, and the behaviour of the Western House Martin is shown in stepwise larger magnification stills of a video.