STAR: Co-infection and animal migration: Novel perspectives from considering multiple parasites

Despite their small size, parasites can change an animal’s behavior: what dog owner has not steered clear of long grassy fields to avoid ticks? Wild animals may not have bug spray or medication to protect them from these pesky parasites, but they have other tricks up their sleeves. This includes moving to habitats that help them recover from an infection or avoid the parasite in the first place. Yet this strategy may lead to an ‘out of the frying pan, into the fire’ situation: A dog walker who moves to a forest path may avoid grass-dwelling ticks but be faced with blood-sucking mosquitoes instead. This balance is also critical for wild migratory animals that travel between different habitats, though how this balance is achieved in nature remains unclear. This project uses mathematical equations and published data to explore how migrating animals time their movement to cope with parasites, just like dog walkers avoiding a forest walk at dusk when mosquitoes are out in full force. It will also explore what happens when migratory animals have more than one infection to deal with, like managing your dog’s infection with both ticks and tapeworms at the same time. The research findings will be communicated to other scientists through conference presentations and publications, and to elementary school and undergraduate students through teaching modules. The project also involves developing Wikipedia pages about scientists, and training graduate students. Despite recognition that parasites can shape seasonal migration of their hosts, important knowledge gaps remain: (i) existing conceptual frameworks typically focus on a single mechanism linking parasites, and (ii) most existing models start with a fully migratory or non-migratory host population in the absence of infection. Via the development of novel theoretical models supported by existing empirical evidence, this project will 1) determine the best timing of migration between two environments, given the tradeoffs of infection with different parasite species inhabiting each environment; and 2) determine how accounting for multiple parasite species changes our understanding of how parasites influence partial migration. Thus, this research generates a comprehensive understanding of the eco-evolutionary interactions between host movement and parasites, something that is essential for predicting the responses of migratory hosts and their parasites to anthropogenic change. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.