The Critically Endangered Grenada Dove Leptotila wellsi has a very small total population size (< 190 individuals) and faces multiple threats. Over eight weeks in 2012 at the Mount Hartman Estate, we investigated the dove’s habitat selection, established a mongoose index of occupancy and recorded dove use of water sources to help determine key research and conservation needs. Of 12 habitat variables measured, greater levels of canopy cover were the best predictor of dove presence. Tracking tunnels indicated that introduced small Indian mongooses Herpestes auropunctatus, widely known for negatively impacting Caribbean bird populations, have a high level of occupancy in dove habitat, providing baseline mongoose data. Trail cameras revealed that Grenada Doves make good use of water from man-made wells and mongooses scent-mark tunnels. We urge fuller habitat selection studies and water-provision experiments to validate this evidence; strong and immediate control of mongooses and other potential predators, particularly at the nest; and a census backed by a banding programme to establish a monitoring baseline to guide conservation actions.