SEEN - SE European Bird Migration Network
Using stable isotopes and ring recoveries to infer avian migratory patterns - lessons from the Reed and Marsh Warblers
Petr Procházka
Institute of Vertebrate Biology AS CR, v.v.i., KvÄ›tná 8, CZ-60365 Brno, Czech Republic

Until recently, ring recoveries have been the most valuable source of information on migration of small passerines. The current accessibility of stable isotope analysis has the potential to bridge the gaps and biases in recovery patterns across the globe. Here I will compare costs and benefits of using stable isotopes and ring recoveries to infer migration patterns in two long-distance migrants, the Reed (Acrocephalus scirpaceus) and Marsh Warblers (A. palustris). Bird ringing is an inexpensive method, which, however, suffers from low and unequal recovery rates. Stable isotope analysis is quick since it does not require recapturing of marked individuals, but its spatial resolution is lower. Both approaches have their weaknesses, yet often provide information that would not be possible to get by other methods. Although stable isotope analysis can answer questions that we would hardly dare to ask before, ring recoveries remain one the most precise sources of geographic information we can get at the moment for small-bodied birds. Nevertheless, a combination of different approaches may help us to study bird migration more efficiently.
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