Trevor Price works on the origin of species, the underlying reasons for why each species has a restricted geographical range, how ranges are being altered in consequence of anthropogenic change. He first worked on Darwin's finches – a famous and young island radiation, and then developed a system to contrast this to a continental radiation, that of the Old World Leaf warblers.
Trevor's research has been almost entirely in India, especially in the Himalaya, a region of exceptional biodiversity. Contrasting the relatively species-poor west Himalaya with the relatively species-rich east Himalaya, for both plants and birds, he assesses the underlying historical reasons for different patterns of biodiversity, and alterations induced by climate change, invasive species, and land use change. In this work, he collaborates with Indian faculty and students, and develops conservation initiatives through the organization SavingNature.org, on which he serves as a board member.
His research and teaching are summarized in two books (Speciation in Birds, 2008; Ecology of a Changed World, 2022).