 He has also authored over 180 scientific publications.He has conducted a number of digs at prehistoric sites and uncovered widescale extinctions caused by humans in the early stages of colonisation.He has conducted several expeditions to the Galápagos Islands, and has described a number of extinct species of birds and more recently was involved in discovering that the Solomon Islands frogmouth is a species (instead of a subspecies of the marbled frogmouth, as formerly believed).