- Habitat destruction associated with hurricanes, especially Gilbert, Roxanne, Emily, and Wilma.
- Introduced predators, especially Boa constrictor (boa snakes).
- Human development & associated land-use change (fragmentation, degradation).
- Introduced diseases.
The Cozumel thrasher (Toxostoma guttatum) is a bird from the mockingbird family (Mimidae), which is endemic to the island of Cozumel off the Yucatán Peninsula, Mexico. It is believed to be the most critically endangered species of bird in Mexico – if it indeed still exists, which is probable but not certain. This bird is closely related to the long-billed and brown thrasher. It has been generally described as shy, but there have been descriptions to the contrary. It was once abundant throughout Cozumel before two hurricanes greatly affected its numbers. Invasive species are also thought to have impacted the population of the thrasher.
The thrasher is 21.5 to 24 cm in length. The adult has a brown crown, back, shoulders, and rump that becomes more red in its tint on its lower back and rump. Greater and lesser coverts are a warm brown with concealed white tips, preceded with a black bar. Primaries and secondaries are grayish-brown with warm rufous-brown outer webs. The rectrices are also have a warm brown color. The lores and ear-coverts are a mottled grey brown. The chin and throat are an off-white color with a blackish partial malar stripe. The chest is a buffy-white in color with stark black teardrop shaped spots. The belly is off-white, and the flanks have larger black spots. Its vent is buffy and an underwing that is buffy-white with darker markings. The iris is yellow, the bill is grayish-brown, and the legs are brown with a dull tint. Juveniles’ plumage have not been recorded, but presumably is similar in development to adulthood like the long-billed and brown thrasher.
The distribution of the thrasher is restricted to Isla Cozumel which is 45 km long and 20 km wide. The habitat preferences for the thrasher is thought to be in low and medium deciduous and semi-deciduous forests. It may have once been most abundant in forest edges adjacent to clearings.