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Toxostoma guttatum 

Scope: Global
Language: English
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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Aves Passeriformes Mimidae

Scientific Name: Toxostoma guttatum
Species Authority: (Ridgway, 1885)
Common Name(s):
English Cozumel Thrasher
Taxonomic Source(s): del Hoyo, J., Collar, N.J., Christie, D.A., Elliott, A., Fishpool, L.D.C., Boesman, P. and Kirwan, G.M. 2016. HBW and BirdLife International Illustrated Checklist of the Birds of the World. Volume 2: Passerines. Lynx Edicions and BirdLife International, Barcelona, Spain and Cambridge, UK.
Identification information: 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.

Assessment Information [top]

Red List Category & Criteria: Critically Endangered B1ab(i,ii,iii,iv,v);C2a(i,ii);D ver 3.1
Year Published: 2016
Date Assessed: 2016-10-01
Assessor(s): BirdLife International
Reviewer(s): Butchart, S. & Symes, A.
Contributor(s): Brewer, D., Howell, S., Salaman, P. & Sweet, P.
Facilitator/Compiler(s): Bird, J., Calvert, R., Capper, D., Isherwood, I., Pople, R., Sharpe, C J & Symes, A.
Justification:
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.

Previously published Red List assessments:

Geographic Range [top]

Range Description: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 1995a, 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).

Countries occurrence:
Native:
Mexico
Additional data:
Continuing decline in area of occupancy (AOO):Yes
Extreme fluctuations in area of occupancy (AOO):NoEstimated extent of occurrence (EOO) - km2:150
Continuing decline in extent of occurrence (EOO):YesExtreme fluctuations in extent of occurrence (EOO):No
Number of Locations:1Continuing decline in number of locations:Yes
Extreme fluctuations in the number of locations:No
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population: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 which has remained so and may have continued to decline. The population is suspected to have experienced a 1-19% decline over the last ten years.

Current Population Trend:Decreasing
Additional data:
Number of mature individuals:1-49Continuing decline of mature individuals:Yes
Extreme fluctuations:NoPopulation severely fragmented:No
No. of subpopulations:1Continuing decline in subpopulations:Yes
Extreme fluctuations in subpopulations:NoAll individuals in one subpopulation:Yes
No. of individuals in largest subpopulation:100

Habitat and Ecology [top]

Habitat and 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 1995a), and the edges of tropical deciduous and semi-deciduous forest (Howell and Webb 1995a, 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 1995a). The breeding season is May-July (S. N. G. Howell in litt. 1998).

Systems:Terrestrial
Continuing decline in area, extent and/or quality of habitat:Yes
Generation Length (years):4.2
Movement patterns:Not a Migrant

Threats [top]

Major Threat(s): 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 because 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 and introduced cats are the leading hypothesised threat (Curry et al. 2006). 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 (BirdLife International unpublished data).

Conservation Actions [top]

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), and efforts are ongoing to determine the remnant population size and distribution, and 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 potential to damage the island's ecosystem (Curry and Martínez-Gómez 2005). Establish formal protection for interior lands on Cozumel (Curry and Martínez-Gómez 2005).


Citation: BirdLife International. 2016. Toxostoma guttatum. The IUCN Red List of Threatened Species 2016: e.T22711105A94277900. . Downloaded on 28 July 2017.
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