Migration distance does not predict blood parasitism in a migratory songbird

Sorensen, M. C., Dixit, T., Kardynal, K. J., Newton, J. , Hobson, K. A., Bensch, S., Jenni-Eiermann, S. and Spottiswoode, C. N. (2019) Migration distance does not predict blood parasitism in a migratory songbird. Ecology and Evolution, 9(14), pp. 8294-8304. (doi: 10.1002/ece3.5404) (PMID:31380090) (PMCID:PMC6662322)

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Migration can influence host–parasite dynamics in animals by increasing exposure to parasites, by reducing the energy available for immune defense, or by culling of infected individuals. These mechanisms have been demonstrated in several comparative analyses; however, few studies have investigated whether conspecific variation in migration distance may also be related to infection risk. Here, we ask whether autumn migration distance, inferred from stable hydrogen isotope analysis of summer‐grown feathers (δ 2Hf) in Europe, correlates with blood parasite prevalence and intensity of infection for willow warblers (Phylloscopus trochilus ) wintering in Zambia. We also investigated whether infection was correlated with individual condition (assessed via corticosterone, scaled mass index, and feather quality). We found that 43% of birds were infected with Haemoproteus palloris (lineage WW1). Using generalized linear models, we found no relationship between migration distance and either Haemoproteus infection prevalence or intensity. There was spatial variation in breeding ground origins of infected versus noninfected birds, with infected birds originating from more northern sites than noninfected birds, but this difference translated into only slightly longer estimated migration distances (~214 km) for infected birds. We found no relationship between body condition indices and Haemoproteus infection prevalence or intensity. Our results do not support any of the proposed mechanisms for migration effects on host–parasite dynamics and cautiously suggest that other factors may be more important for determining individual susceptibility to disease in migratory bird species.

Item Type:Articles
Additional Information:Isotope analyses at the LSMSF were funded by a NERC LSMSF grant (EK206-16/12). MCS was funded by the Gates Cambridge Trust and the Natural Sciences and Engineering Research Council of Canada. CNS was supported by a Royal Society Dorothy Hodgkin Fellowship, a Biotechnology and Biological Sciences Research Council David Phillips Fellowship (BB/J014109/1), and the DST-NRF Centre of Excellence at the FitzPatrick Institute of African Ornithology.
Glasgow Author(s) Enlighten ID:Newton, Dr Jason
Authors: Sorensen, M. C., Dixit, T., Kardynal, K. J., Newton, J., Hobson, K. A., Bensch, S., Jenni-Eiermann, S., and Spottiswoode, C. N.
College/School:College of Science and Engineering > Scottish Universities Environmental Research Centre
Journal Name:Ecology and Evolution
ISSN (Online):2045-7758
Published Online:01 July 2019
Copyright Holders:Copyright © 2019 The Authors
First Published:First published in Ecology and Evolution 9(14):8294-8304
Publisher Policy:Reproduced under a Creative Commons licence

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