CR
Cozumel Thrasher Toxostoma guttatum



Justification

Justification of Red List Category
This formerly common species appears to have declined rapidly following a hurricane in 1988, with very few subsequent records, despite repeated surveys since then. Any remaining population is likely to be tiny, and for these reasons it is treated as Critically Endangered.

Population justification
Any remaining population is assumed to be tiny (numbering fewer than 50 individuals and mature individuals), given the low number of records during the past decade.

Trend justification
The species is suspected to have declined extremely rapidly around the time of Hurricane Gilbert in 1988. Since 1994-1995, when just four records were obtained from monthly survey visits, it has apparently had a tiny population. The paucity of recent records make it difficult to clearly ascertain the population trend, but any remaining population is tentatively suspected to be in decline.

Distribution and population

This species is endemic to Cozumel Island, Mexico, where it was formerly fairly common to common (AOU 1998). It became rare immediately after Hurricane Gilbert in September 1988 (Howell and Webb 1995, S. N. G. Howell in litt. 1998, Macouzet and Escalante Pliego 2001), with only four records obtained during monthly visits to the island during August 1994-August 1995 (Macouzet and Escalante Pliego 2001). Only a few sightings were been recorded after Hurricane Roxanne in 1995, the most recent being four observations of what is presumed to have been the same individual during extensive surveys in 2004 and a record from a different site during the same year (Curry et al. 2006). There remains only one possible sighting made in 2006 since two further devastating hurricanes hit the island in 2005 (P. Salaman in litt. 2007).

Ecology

Recent records originate from semi-deciduous forest and deciduous forest away from scrubby areas (Macouzet and Escalante Pliego 2001). However, it was formerly reported to inhabit scrubby woodland and thick undergrowth bordering fields (Howell and Webb 1995), and the edges of tropical deciduous and semi-deciduous forest (Howell and Webb 1995, S. N. G. Howell in litt. 1998). It is typically known to skulk on or near the ground, but often sings from conspicuous perches (Howell and Webb 1995). The breeding season is May-July (S. N. G. Howell in litt. 1998).

Threats

Hurricane Gilbert appears to have had a severe effect on the species, whose status may have deteriorated further following Hurricane Roxanne in 1995 and Hurricanes Emily and Wilma in 2005 (Macouzet and Escalante Pliego 2001, Curry et al. 2006). Further hurricanes are likely, as Cozumel lies within the area of Mexico most frequently hit by hurricanes (Stattersfield et al. 1998), and may extirpate any surviving, small populations. However, this seems an unsatisfactory explanation of its current rarity, because it must have evolved with a relatively high hurricane frequency. The reasons behind its decline are poorly understood, but boa constrictors introduced in 1971, as well as introduced cats and other mammals, are the leading hypothesised threat (Curry et al. 2006, J. E. Martínez-Gómez in litt. 2016), while habitat fragmentation as a result of the development of tourism on the island may also be impacting the species (J. E. Martínez-Gómez in litt. 2016). Having a distribution on a relatively low-lying island, this species is potentially susceptible to climate change through sea-level rise and shifts in suitable climatic conditions (Şekercioğlu et al. 2012, BirdLife International unpubl. data).

Conservation actions

Conservation Actions Underway
There have been several recent searches for the species (S. N. G. Howell in litt. 1998, D. Brewer in litt. 1999, Macouzet and Escalante Pliego 2001). Efforts are ongoing to determine the remnant population size and distribution, as well as to evaluate the threats and reasons behind its decline (Curry and Martínez-Gómez 2005).

Conservation Actions Proposed
Urgently survey in the breeding season (when it is most conspicuous) to determine whether the species is still extant and identify appropriate conservation measures. Investigate its former status and ecology through interviews with local people to ascertain the reasons for its decline. Conduct an awareness raising campaign to raise the profile of this species and educate visitors about the risk of damaging the island's ecosystem (Curry and Martínez-Gómez 2005). Establish formal protection for interior lands on Cozumel (Curry and Martínez-Gómez 2005).

Identification

23 cm. Brown-and-white bird with long, decurved bill. Rich chestnut-brown above with two white wing-bars. Greyish face with paler supercilium. White underparts heavily streaked black. Black bill and legs. Voice Complex scratchy warbling.

Acknowledgements

Text account compilers
Capper, D., Calvert, R., Isherwood, I., Pople, R., Bird, J., Sharpe, C.J., Symes, A., Westrip, J.

Contributors
Salaman, P., Howell, S., Martínez-Gómez, J.E., Brewer, D.


Recommended citation
BirdLife International (2019) Species factsheet: Toxostoma guttatum. Downloaded from http://www.birdlife.org on 18/08/2019. Recommended citation for factsheets for more than one species: BirdLife International (2019) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 18/08/2019.