Blood parasites prevalence of migrating passerines increases over the spring passage period. (5th June 2018)

• Record Type: Journal Article
• Authors: Emmenegger, T.; Bauer, S.; Hahn, S.; Müller, S. B.; Spina, F.; Jenni, L.
• Is Part Of: Journal of zoology. Volume 306:Number 1(2018)
• Page Start: 23
• Page End: 27
• Publication Date: 2018-06-05
• Subjects: blood parasites -- haemosporida -- immune response -- migration timing -- spring passage -- stopover -- passerines -- parasite transmission; Zoology -- Periodicals; Zoologie -- Périodiques; 590.5
• DOI: 10.1111/jzo.12565
• Languages: English
• ISSNs: 0952-8369

Abstract

Abstract: Whether long‐distance animal migration facilitates or hampers pathogen transmission depends on how infections affect the routes and timing of migrating hosts. If an infection directly or indirectly impedes migratory flight capacity, infected individuals lag behind their uninfected conspecifics. Although such temporal segregation can limit parasite transmission and thus play an important role for host–parasite interactions, empirical evidence remains scarce. Here, we investigated haemosporidians – blood parasites commonly infecting birds – in four passerine species on spring passage and linked infection status to passage date. As a step towards identifying the mechanisms behind infection‐related delays, we incorporated sets of individual, energetic, haematological and biometric variables into the analysis. Haemosporidian prevalence virtually doubled between birds sampled at the beginning of the passage period with those sampled 1 month later. This indicates that infected individuals arrived later than uninfected individuals. Both the average prevalence and its increase over time varied among host species. In addition, the leucocyte counts of infected birds were elevated, suggesting that immune response may require resources which could otherwise be allocated to migratory flights. However, infection status was not related to any other variable such as body mass, energy stores, sex, age and feather length. Yet regardless of the underlying mechanisms, infection‐related differential timing might influence transmission and affect pathogen prevalence in wildlife populations year‐round. Abstract : We investigated blood parasites in several passerine species on a migratory stopover site. The prevalence almost doubled over 1 month during spring passage, and this indicates that infected individuals arrive later than their uninfected counterparts. As migrants gather in great numbers at migration hotspots, this pattern might be beneficial for the birds: even small differences in prevalence and in the timing of migration may reduce transmission rates compared to when infected and uninfected individuals migrate in mixed waves. Migratory allochrony – i.e. infection‐induced delays in timing of migration – may play a decisive role in the transmission dynamics on a population level.