Population trends and viability of the critically endangered Cozumel Curassow: a 25-year perspective

Abstract

The Cozumel Curassow (Crax rubra griscomi) is a critically endangered endemic bird from Cozumel Island, Mexico. After it was believed to be extinct, it was rediscovered in 1994. Its population status was assessed in 1994–1995, and later in 2005, predicting a population decline over the next four decades. A new evaluation of its population size was carried out in 2017 and 2019. Some of the main factors that affect the population size of this cracid were identified with a generalized linear model. With a line transect sampling effort over 360 km, a population size of 499 ± 172 individuals was estimated in the tropical semi-deciduous forest occurring in the island, which was slightly higher compared to previous population evaluations. The distance to water bodies was significantly associated with the population size of the Cozumel Curassow, as well as the abundance of some species of fauna and flora. By modeling various scenarios, population viability was assessed over a period of 100 years, predicting a relatively stable population size with great variability depending on scenarios. However, as estimated in previous studies, given its small population size and continued threats, the Cozumel Curassow continues to be endangered.