Prey size affects global distribution of the golden eagle
Submitted by avianbiology on 7 October 2014.
In this study we show that the availability of optimal-sized prey (between 0.5-5 kg) is a crucial driver of foraging behaviour, breeding success and distribution patterns of the Golden Eagle Aquila chrysaetos L. on a continental scale.
The initial idea for our study arise from observations about the feeding behaviour of breeding Golden Eagles, which were conducted in the Bavarian Alps (Southern Germany) over a period of 10 years (1998-2008). Located at the northern range edge within the European Alps, breeding success of the birds studied is remarkably low in comparison to populations in the centre of the Alps (e.g. Switzerland). Furthermore, Bavarian Golden Eagles forage on a wide range of prey including large ungulates (Chamois, Roe deer) and mesopredators (Red fox), together with small passerines, rodents, reptiles and amphibians. In comparison, Golden Eagles in the central part of this distribution area are known to be highly specialised for foraging optimal-sized marmots with an average weight of about 3-4 kg.
To test the generality of the observations we made on regional scale, we combined our own data with 64 literature accounts about the diet choices, breeding success and distribution patterns of Golden Eagles of from the entire Northern Hemisphere.
Read the paper online: http://onlinelibrary.wiley.com/doi/10.1111/jav.00396/abstract
Photos by: Jochen Fünfstück www.5erls-naturfotos.de