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Migration distance does not predict blood parasitism in a migratory songbird.

Accepted version
Peer-reviewed

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Authors

Sorensen, Marjorie C  ORCID logo  https://orcid.org/0000-0002-5556-0502
Dixit, Tanmay 
Kardynal, Kevin J 
Newton, Jason 
Hobson, Keith A 

Abstract

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.

Description

Keywords

Palearctic–African songbird, disease ecology, malaria parasites, migration

Journal Title

Ecol Evol

Conference Name

Journal ISSN

2045-7758
2045-7758

Volume Title

9

Publisher

Wiley

Rights

All rights reserved
Sponsorship
Biotechnology and Biological Sciences Research Council (BB/J014109/1)
Royal Society (RG2010/RZ)
BBSRC NERC Royal Society Gates Cambridge Trust DST-NRF, South Africa