The ecology of pathogens, and particularly their emergence in multi-host systems, is complex. New approaches are
needed to reduce superficial complexities to a level that still allows scientists to analyse underlying and more
fundamental processes. One promising approach for simplification is to use an epidemiological-function
classification to describe ecological diversity in a way that relates directly to pathogen dynamics. In this article, we
develop and apply the epidemiological functional group (EFG) concept to explore the relationships between wild
bird communities and avian influenza virus (AIV) in three ecosystems in southern Africa. Using a two year dataset
that combined bird counts and bimonthly sampling for AIV, we allocated each bird species to a set of EFGs that
captured two overarching epidemiological functions: the capacity of species to maintain AIV in the system, and
their potential to introduce the virus. Comparing AIV prevalence between EFGs suggested that the hypothesis that
anseriforms (ducks) and charadriiforms (waders) drive AIV epidemiology cannot entirely explain the high prevalence
observed in some EFGs. If anseriforms do play an important role in AIV dynamics in each of the three ecosystems,
the role of other species in the local maintenance of AIV cannot be ruled out. The EFG concept thus helped us to
identify gaps in knowledge and to highlight understudied bird groups that might play a role in AIV epidemiology.
In general, the use of EFGs has potential for generating a range of valuable insights in epidemiology, just as
functional group approaches have done in ecology.