Prädationseinfluss und Feindvermeidungsstrategien beim Auerhuhn Tetrao urogallus/ Influence of predation and predator-avoidance strategies in the Capercaillie
Auteur : Müller (Franz)
Année de publication : 2009
Publication : Ornithologischer Anzeiger
Volume :
48
Pagination : 56-59
Résumé :
Capercaillies have a number of abilities which help them to avoid predators: very good eyesight and hearing, camouflage colour and behaviour, fast flight, if necessary effective defence (especially by cock birds) or deception (injury-feigning by hen birds). Their sedentary nature promotes a knowledge of escape routes and hiding places; life in social groups reduces the threat from enemies through visual and audible warnings and because different birds look out in turn.The influence of predation can only be assessed indirectly by finding the remains of killed birds. Since not all of these are found, minimum values result. Findings in a relict population in 1000 ha of the Vorderrhön, Hessen between 1962 and 1980 give a to some extent realistic indication of affairs in the Central Uplands. Annual losses of adult birds fluctuated strongly (0 – 50%, mean 12%). Ten years of trials with artificial clutches resulted mostly in total losses so long as wild pigs were present. Only when this predator was temporarily eliminated did losses fall to about 30% – considered to be a normal level amongst ground-nesting species.