Functional connectivity and population persistence in woodland birds: insights for management from a multi-species conservation genetics study

Conservation management of wildlife benefits from understanding the genetic factors underlying individual fitness and population evolution. Habitat loss and fragmentation reduce genetic diversity and functional connectivity, limiting population persistence and adaptation to changing environments. Here we review and synthesise results from the Birds in Fragmented Landscapes program in central Victoria, Australia. Building on research on patterns of occurrence of woodland-dependent bird species, we conducted conservation genetic studies of ~3,500 individuals from 10 woodland bird species sampled in twelve 100 km² ‘landscapes’ with different levels of habitat loss, to assess multiple conservation-relevant processes of response to habitat alteration. This program employed connectivity modelling and landscape-, acoustic- and population genetic analyses to understand mobility of birds, their genes and songs at different scales, relating these elements of functional connectivity to landscape structure for each sex in each species. At the regional scale, most species displayed unexpectedly high levels of genetic connectivity. At local-scales, there were strong signals of disrupted population processes (e.g. mating system) and reduced functional connectivity for several more-mobile and all less-mobile ‘decliner’ species. This underlines that high genetic connectivity does not necessarily signal genetically and demographically healthy populations. In some species, declines in mobility were greater in one sex but not necessarily the more philopatric sex. We derive conservation management recommendations in five concept areas: maintain existing and restore degraded habitat, reconnect the landscape, use species- and sex-specific information where possible, work across multiple scales, and conserve evolutionary processes (by genetic management where appropriate).