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Constitutive immune function is not associated with fuel stores in spring migrating passerine birds
  • Shivani Ronanki,
  • Arne Hegemann,
  • cas eikenaar
Shivani Ronanki
Wageningen University & Research

Corresponding Author:[email protected]

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Arne Hegemann
Lund Univeristy
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cas eikenaar
Institute of Avian Research
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Migratory birds may either upregulate their immune system during migration as they might encounter novel pathogens or downregulate their immune system as a consequence of trade-offs with the resource costs of migration. Support for the latter comes not least from a study that reports a positive correlation in autumn migrating birds between fuel stores and parameters of innate and acquired immune function, i.e., energy exhausted migrants appear to have lowered immune function. However, to our knowledge, no study has tested whether this pattern exists in spring migrating birds, which may face other trade-offs than autumn migrants. Here, we investigate if in spring there is a relationship between fuel stores and microbial killing ability, a measure of innate immune function, and total immunoglobulin (IgY), a measure of acquired immune function, in four migrating bird species: Chaffinches (Fringilla coelebs), Dunnocks (Prunella modularis), Song thrushes (Turdus philomelos) and Northern wheatears (Oenanthe oenanthe). We found no correlation between fuel stores and bacterial killing ability or IgY levels in any of the species. However, there was a significant negative correlation between microbial killing ability and Julian date in Song thrushes and Northern wheatears, and between IgY levels and Julian date in Song thrushes. Sex did not affect immune function in any of the species. Our study suggests that the relationship between immune function and fuel stores may be different during spring migration compared to autumn migration. Differences in the speed of migration or pathogen pressure may result in different outcomes of the trade-off between investment in immune function and in migration among the seasons.
04 May 2023Submitted to Ecology and Evolution
13 May 2023Submission Checks Completed
13 May 2023Assigned to Editor
15 May 2023Reviewer(s) Assigned
18 Jul 2023Review(s) Completed, Editorial Evaluation Pending
24 Jul 2023Editorial Decision: Revise Minor
30 Oct 20231st Revision Received
04 Nov 2023Submission Checks Completed
04 Nov 2023Assigned to Editor
04 Nov 2023Review(s) Completed, Editorial Evaluation Pending
06 Nov 2023Reviewer(s) Assigned
18 Mar 20242nd Revision Received