The paper “An advection and stage-structured approach to modeling bird migration and indirect transmission of avian influenza“, co-authored by Stephen Gourley, Rachel Jennings (University of Wyoming), and Rongsong Liu (University of Wyoming), has been published in the SIAM Journal of Applied Mathematics.   In the paper, they model indirect transmission, via contact with viruses, of avian influenza in migratory and nonmigratory birds, taking into account age structure.  Migration is modeled via a reaction-advection equation on a closed loop parametrized by arc length (the migration flyway) that starts and ends at the location where birds breed in summer. A link to the published paper is here.