Dauerbeobachtung von Singvogelnestern mit Hilfe von Videokameras. Eine Pilotstudie

Abstract

About 50 of songbird nests in Central Europe fall victim to predators. It is rarely possible to identify these predators with certainty. The present study was designed (i) to discover, if possible, what nest predators there are in a small region around Schloß Möggingen, by continuously monitoring nests of the Blackcap (Sylvia atricapilla) there; (ii) to test the suitability of the videotechnique for larger-scale investigations; and (iii) to collect data on the breeding biology of this warbler species.During ten weeks, from May to July 1998, fifteen nests were monitored by time-lapse video equipment, with infrared illumination for the hours of darkness. Eight of these nests were robbed, by the following predators: Jay (Garrulus glandarius, prey: young and eggs), Red-backed Shrike (Lanius collurio: eggs), Eurasian Dormouse (Muscardinus avellanarius: eggs), Eurasian Badger (Meles meles: eggs), Stone-Marten (Martes foina: young) and Stoat (Mustela erminea: young). Sometimes the entire brood was taken, at other times only part of it; in the latter case, the remainder was eaten later by the same predator or one of another species.Apart from the absence of the brood, the nests showed no sign at all of what had happened. Evidently, then, video monitoring is the only reliable method of identifying predators.The extent to which the predators were affected by the monitoring setup, in particular by the IR radiators as a source of light or heat, is not yet clear. The birds being observed usually seemed restless on the first day, while the equipment was being installed, and after the camera was in place they stayed away from the nest for up to an hour. Then they soon settled down, and none of the nests was abandoned.With respect to breeding biology, this approach opens the way to many interesting new research aspects - for instance, regarding the incubation rhythm, the singing of males on the nest, the behaviour of the young when fledging, construction activities during