Predicted population trends for Cozumel Curassows (Crax rubra griscomi): empirical evidence and predictive models in the face of climate change

Abstract

We assessed the current conservation status and population trends of Cozumel Curassows (Crax rubra griscomi), a critically endangered and endemic cracid of Cozumel Island, Mexico. Distance sampling was used to estimate the population size in 2005 and compare it with a previous estimate in 1995. Population viability analysis (PVA) was used to model population trends, considering ecological and environmental conditions prevailing in 1995 and 2005. Additional PVA models were constructed using different hypothetical scenarios to assess the effects of particular factors and management strategies on population trends. We estimated a population size of 372 ± 155 curassows in the island's tropical semideciduous forest, before two hurricanes hit Cozumel Island in 2005. PVA modeling predicted a steep decline in population size in the ensuing decades as a result of an increased frequency and intensity of hurricanes related to global climate change, and an observed female bias in the sex ratio likely caused by a higher mortality rate for adult males. We recommend urgent management actions for the long-term conservation of Cozumel Curassows, including a ban on hunting, eradication of the feral fauna, particularly dogs, and implementation of a captive-breeding program to supplement the wild population. RESUMEN. Tendencias poblacionales estimadas para el hocofais´