Abstract Mexico ranks third globally in seabird diversity and second in the number of endemic species that breed within its territory, yet 16% of seabird species in the country are categorized as threatened on the IUCN Red List, including the Critically Endangered Townsend’s shearwater Puffinus auricularis . Nearly 20 years ago, the breeding population of Townsend’s shearwater, which is endemic to the Revillagigedo Archipelago of Mexico, was inferred to comprise < 100 breeding pairs. Since then, conservation initiatives have been implemented in the archipelago. We assessed the current status of Townsend’s shearwater by mapping the distribution of breeding colonies, estimating breeding population size, evaluating reproductive success, describing ongoing threats and modelling population trends under three conservation scenarios. During 2016–2024, we conducted field surveys on the islands of Socorro and Clarión using acoustic monitoring techniques in historical nesting areas. We estimated that the breeding population on Socorro comprises < 200 pairs and documented the return of a small breeding population to Clarión after a 30-year absence. However, reproductive failure persists because of the effects of native predators such as land crabs, snakes and ravens. The population has exhibited a slow decline driven by interactions between native and invasive species. Without ongoing restoration efforts and management actions, including the removal of feral cats, the population could face extinction.
Solís-Carlos et al. (Fri,) studied this question.