SEEN - SE European Bird Migration Network
Connectivity in Paddyfield Warbler (Acrocephalus agricola Jerd.) - orientation behavior, avian malaria and genetic variability of the population.

Pavel Zehtindjiev1, Mihaela Ilieva1, Bengt Hansson2 & Staffan Bensch 2
1 Insitute of Zoology, Bulgarian Academy of Sciences, Blvd. Tzar Osvoboditel 1, 1000 Sofia Bulgaria
2 Department of Ecology, Lund University, Ecology Building, SE-223 62 Lund, Sweden

According to our results European Paddyfield Warblers still follow the route of their historical breeding range expansion during the seasonal migrations. The Bulgarian population circumvents the Black Sea in autumn. The migratory program in adult and first year birds includes changes from NNE to SE direction with the progress of the autumn season. The switch is not gradual. Population sizes vary considerably across the breeding range. In order to investigate whether the specific orientation behavior of Bulgarian birds correlates with the population structure of the species we analyzed the genetic variability and the prevalence of malaria parasites using samples from three localities in the breeding range. A portion of the mitochondrial control region (456 bp) was sequenced in 104 Paddyfield Warblers sampled in 3 breeding populations in Bulgaria, Russia and Kazakhstan. There was little evidence of divergence between Bulgarian and Russian populations (Fst: -0.0024) whereas the samples from Kazakhstan differed significantly from the European breeding populations (Fst: 0.033 Russian/Kazakhstan and 0.046 Bulgarian/Kazakhstan). The degree of microsatellite differentiation was weaker than was the case for the mtDNA data, which may be explained by differences in effective long-term population size and/or in the mutation-drift equilibrium for these two types of markers. The overall prevalence of haemosporidian parasites was 28%. The most common haemosporidian infection in the breeding Bulgarian population was a new lineage of Haemoproteus described for the first time in the present study. Parasites of the genus Plasmodium were present only in Russian and Bulgarian birds. One lineage was found only in birds breeding in Kazakhstan or at the border region with Russia. The lack of Plasmodium infections in the Kazakhstan population and abundance of these parasites in Russian and Bulgarian birds indicate different wintering sites and migratory routes of the populations.

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