First insights into the migration route and migratory connectivity of the Paddyfield Warbler using geolocator tagging and stable isotope analysis
Abstract
The Paddyfield Warbler Acrocephalus agricola has recently expanded its breeding range westwards to the western coast of the Black Sea. Although its non-breeding range is known (southern Iran to northern Myanmar), current knowledge on how individual birds migrate and how their routes evolve alongside range expansion processes is very limited.
Data from one geolocator deployed on a Paddyfield Warbler at a recently established breeding site in Bulgaria show that this individual retraced the recent range expansion and followed a rather conservative route instead of migrating directly to India. An additional stable hydrogen (delta H-2) analysis of feathers from 25 individual breeding birds in Bulgaria that had been grown during their stay in the non-breeding grounds indicated a low degree of migratory connectivity at the non-breeding grounds.
Our results provide a first insight into the migration pattern of the Paddyfield Warbler and should stimulate further research on the use of the understudied Indo-European flyway by this species.