Large ground-dwelling Neotropical gamebirds are highly threatened by habitat loss and hunting, but conservationists rarely attempt to distinguish between these two threats in the management of populations. We used three different types of species records to determine the status (i.e. persistence level) of the Endangered red-billed curassow Crax blumenbachii in 14 forest remnants in north-east Brazil, as either persistent, precarious or extirpated. We related these persistence levels to variables measured in a 2-km buffer radius, including variables associated with habitat quality (proportion of forest cover, length of rivers, patch density, distance from rivers) and hunting pressure (proportion of cacao agroforests and farmlands, length of roads, total area occupied by settlements, distance from roads and from settlements). Curassows were more persistent in forest patches located (1) more distant from settlements, (2) in landscapes with few settlements, (3) in landscapes with a high incidence of roads, (4) in a mosaic with a high proportion of forest, shaded cacao agroforest and farmland, and (5) more distant from other forest patches. Hunting pressure potentially exerts more influence on persistence than habitat quality: (1) hunting pressure submodels had a higher explanatory power than habitat quality submodels, (2) final models comprised four hunting pressure variables but only two habitat quality variables, and (3) hunting pressure variables appeared in all models whereas habitat quality variables appeared in only one final model. If hunting pressure is driving declines in curassows, regions with low human presence and a high proportion of forest cover are recommended for establishing new reserves.

The Endangered red-billed curassow Crax blumenbachii is endemic to the lowland Atlantic Forest of Brazil and is extinct across most of its range as a result of habitat loss and hunting pressure. Global population estimates are unreliable as the species has never been surveyed systematically. During March 2012–February 2013 we used line transects to estimate the density and size of one of the most important populations, in the Vale Nature Reserve. Using Distance we estimated a density of 1.3 individuals per km2; results stratified by sex indicated a male-skewed sex ratio. Data collected from motion-activated cameras confirmed that the population was male skewed but to a lesser degree than suggested by transect data. Sex-specific behavioural responses to the presence of an observer probably contributed to the difference between camera and transect data. Using the camera-derived sex ratios we corrected transect estimates to 1.6 individuals per km2 and a population of 325 individuals. Our systematic survey approach has revealed that Vale Nature Reserve has a larger population than previous estimates of the global population. We show that behavioural differences between the sexes in cryptic species can mislead population estimates, and we highlight the importance of motion-activated cameras as a tool for studying cryptic forest species.