Ardea
Official journal of the Netherlands Ornithologists' Union

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Mouritsen H. (2001) Ringing recoveries contain hidden information about orientation mechanisms. ARDEA 89 (1): 31-42
Ringing recoveries are normally used to elucidate where and when specific populations of birds migrate. So far, however, ringing data have rarely been used to answer questions about how the birds' orientation mechanisms function to produce the patterns found in recovery data. The main reason for the lack of study is due to the vast number of birds, which an experimenter must ring in order to produce sufficient recovery data. However, existing recovery data collected during the entire first century of ringing can actually be used for studying orientation mechanisms. This can be done by examining the distribution of recoveries after all ringing and recovery sites have been parallel displaced to originate at one common point. Such an analysis has been performed on Pied Flycatchers Ficedula hypoleuca. It showed that a simple clock-and-compass/vector navigation strategy is sufficient to explain the distribution of young Pied Flycatchers. An equivalent analysis on European Robins Erithacus rubecula is presented, which will highlight some of the potential pit-falls of this type of approach. Finally, some important ecological implications of using a vector navigation strategy are discussed


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