skip the tropics ... avoid malaria parasites?
Animal migrations help us understand how species are distributed across space and time. Many migratory animals travel huge distances each year, leaving us to wonder why such long migration routes are necessary. One possible explanation is the avoidance of harmful parasite infections (migratory escape). Some of the most impressive migrations are shown by wading shorebirds (waders), with some species travelling over 22,000km on migrations from arctic breeding grounds to non-breeding grounds in the southern hemisphere. In two recent papers, published in OIKOS (full text here and a blogpost by the journal here) and Oecologia (full text here), we tested if different migration patterns expose waders to different malaria parasite infection risk across the globe.
Using Bayesian models to account for bird relatedness (MCMCglmm in R), our key findings show that migratory waders that avoid tropical non-breeding grounds, often by actually flying further to more southern latitudes, have a decreased risk of avian malaria parasite infection. We also provide evidence that waders that only use saltwater coastlines have lower avian malaria infection rates than species that use both oceanic and freshwater habitats. The patterns shown here indicate that malaria parasites could influence migration patterns and habitat use in waders, providing a platform for future studies of migration and parasitic disease risk.
Clark, NJ, Clegg, SM and Klaassen, M. 2016. Migration strategy and pathogen risk: non-breeding distribution drives malaria prevalence in migratory waders. Oikos doi: 10.1111/oik.03220
2016 Aharon-Rotman, Y, Buchanan, KL, Clark, NJ, Klaassen, M and Buttemer, WA. Why fly the extra mile? Using stress biomarkers to assess wintering habitat quality in migratory shorebirds. Oecologia doi: 10.1007/s00442-016-3679-1