Global population size and conservation priority areas for the endangered Titicaca grebe

The Titicaca grebe (Rollandia microptera) is a poorly studied endangered species, only found in the Lake Titicaca watershed of Peru and Bolivia. Population surveys undertaken in the early twenty-first century suggested that the species had declined in number by >70%. We conducted a population survey of the grebe between March and August 2022 in Peru and Bolivia, using both maximum entropy and Bayesian occupancy models to estimate factors affecting habitat suitability for the grebe. We conducted surveys between March and August 2022 in Peru and Bolivia. Contrary to the International Union for Conservation of Nature (IUCN) population estimates of <1,000 individuals, there are likely tens of thousands of individual grebes. The population estimation was sensitive to the type of model used. Distance from shore and fishing intensity were the most significant factors influencing grebe populations. The Reserva Nacional del Titicaca, the only protected area in the lake, covers some of the most suitable Titicaca grebe habitat across its entire range. The population of the Titicaca grebe is significantly higher than previous estimates, but we do not recommend a change to its conservation status because of the lack of conservation efforts for this species, and the long-term risks associated with global warming and fisheries bycatch.