The large volume of experimental work* by the author, and his associates at the Max- Planck-Institut, is not as well known in Britain as it ought to be, much of it having been published in the German language. This short review stems from a paper read by Professor Bert hold at the Trust's Ringing and Migration Conference held at Swan wick (Derbyshire) in January 1983.
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Peter R. Berthold (1984) studied this question.
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