Professor David M Watson's research falls into three principal areas: managing biodiversity in agricultural landscapes; measuring and predicting the biological effects of habitat fragmentation; and the ecology of parasitic plants. His research has been conducted through detailed community-level field studies in Australia and Latin America; species-specific studies of distribution and abundance; theoretical advances; empirical studies based on previously published data; & synthetic reviews consolidating existing information and proposing new hypotheses. Most of his research is applied, improving our understanding and management of natural systems. He has developed a new way of conducting bird surveys; articulated a generalised explanation for distribution patterns of parasitic plants; demonstrated parasitic plants boost productivity in their communities; & suggested changes in productivity and food availability underlie woodland bird declines.