Effects of blood parasite infections on spatiotemporal migration patterns and activity budgets in a long-distance migratory passerine.

Tamara Emmenegger,Staffan Bensch,Silke Bauer,Steffen Hahn,Petr Procházka,Dmitry Kishkinev,Pavel Zehtindjiev

doi:10.1002/ece3.7030

Abstract

How blood parasite infections influence the migration of hosts remains a lively debated issue as past studies found negative, positive, or no response to infections. This particularly applies to small birds, for which monitoring of detailed migration behavior over a whole annual cycle has been technically unachievable so far. Here, we investigate how bird migration is influenced by parasite infections. To this end, we tracked great reed warblers (Acrocephalus arundinaceus) with multisensor loggers, characterized general migration patterns as well as detailed flight bout durations, resting times and flight heights, and related these to the genus and intensity of their avian haemosporidian infections. We found migration distances to be shorter and the onset of autumn migration to be delayed with increasing intensity of blood parasite infection, in particular for birds with Plasmodium and mixed‐genus infections. Additionally, the durations of migratory flight bout were prolonged for infected compared to uninfected birds. But since severely infected birds and particularly birds with mixed‐genus infections had shorter resting times, initial delays seemed to be compensated for and the timing in other periods of the annual cycle was not compromised by infection. Overall, our multisensor logger approach revealed that avian blood parasites have mostly subtle effects on migratory performance and that effects can occur in specific periods of the year only.

Highlights

Infection-related deviations in host migration performance have already been described for a variety of parasite and host taxa: Monarch butterflies migrated slower when infected by ectoparasites (Bradley & Altizer, 2005), reindeer herds with more ectoparasites performed shorter migrations (Folstad, Nilssen, Halvorsen, & Andersen, 1991) and the timing of arrival at the breeding site was delayed for blood parasite infected compared to uninfected passerines (Rätti, Dufva, & Alatalo, 1993)
The recorded patterns were related to the parasite genus and the individual intensities of avian haemosporidian parasite infections assessed by real-time quantitative PCR
If partial oxygen pressures experienced aloft are limiting for migrating birds, we expect infected individuals to fly at lower altitudes. All these potential effects are expected to increase with growing intensity of infection and are to some degree expected to differ between parasite genera, as Haemoproteus and Plasmodium infections are known to differ in their average pathogenicity and co-infections with several genera are known to be most virulent (Valkiūnas, 2005)

Summary

Introduction

Infection-related deviations in host migration performance have already been described for a variety of parasite and host taxa: Monarch butterflies migrated slower when infected by ectoparasites (Bradley & Altizer, 2005), reindeer herds with more ectoparasites performed shorter migrations (Folstad, Nilssen, Halvorsen, & Andersen, 1991) and the timing of arrival at the breeding site was delayed for blood parasite infected compared to uninfected passerines (Rätti, Dufva, & Alatalo, 1993). Seminal works indicated that Plasmodium infections decreased the oxygen consumption rates of experimentally infected canaries during nocturnal rest (Hayworth, Riper, & Weathers, 1987) and naturally infected lizards during exercise (Schall, Bennett, & Putnam, 1982). Benign avian influenza infections lowered the feeding rates and prolonged stop-over durations in migratory swans (van Gils et al, 2007) and infections with multiple intestinal parasites were correlated with delayed spring migration timing in passerines (López, Muñoz, Soriguer, & Figuerola, 2013).

Results

Conclusion