Species

Justification
This species has been downlisted to Least Concern because it is no longer thought to be undergoing moderately rapid population declines, and is not thought to approach the thresholds for classification as Vulnerable under any other criteria. Nevertheless, the total population is thought to be moderately small and habitat loss remains a threat, and indications that the population is smaller than currently suspected, or undergoing rapid declines, would warrant reconsideration of its threat status.

Taxonomic source(s)
AOU. 1998. Check-list of North American birds. American Ornithologists' Union, Washington, D.C.
Sibley, C. G.; Monroe, B. L. 1990. Distribution and taxonomy of birds of the world. Yale University Press, New Haven, USA.
Stotz, D. F.; Fitzpatrick, J. W.; Parker, T. A.; Moskovits, D. K. 1996. Neotropical birds: ecology and conservation. University of Chicago Press, Chicago.

Distribution and population
Vermivora crissalis is a fairly common but local breeder, occurring from Coahuila to north-east Zacatecas and northern San Luis Potosí, Mexico, and extreme south-west Texas, USA (Curson et al. 1994, Howell and Webb 1995a). It winters in west Mexico from south Sinaloa south to Guerrero and Morelos (Howell and Webb 1995a).

Population justification
Rich et al (2003)

Trend justification
This species is suspected to be in slow to moderate decline owing to habitat degradation.

Ecology
It breeds in pine-oak, oak and pinyon-juniper woodland, between 1,500 and 3,000 m (Curson et al. 1994, Howell and Webb 1995a), and is commonest in pine-oak woodland with a ground cover of bunchgrass (Wauer 1994). It winters in brushy understorey of humid to semi-humid montane forest from 1,500 to 3,500 m (Howell and Webb 1995a). The nest is usually on the ground, and eggs have been found in May (Curson et al. 1994).

Threats
Grazing by goats, sheep and other exotic herbivores, increases in the populations of feral cats and dogs, and nest parasitism by Brown-headed Cowbirds Molothrus ater are potentially severe threats to populations of this warbler in Mexico (Wauer 1994).

Conservation actions underway
None are known.

Conservation actions proposed
Regularly monitor the population at selected sites across its range to determine trends. Research the effects of grazing and wood cutting on populations of the species. Examine the effects of Brown-headed Cowbird parasitism at the population level. Protect significant areas of forest, in both strictly protected areas and community led multiple use areas.

References
Wauer, R. 1994. A closer look: Colima warbler. Birding 26: 250-253.

Curson, J.; Quinn, D.; Beadle, D. 1994. New World warblers. A&C Black/Christopher Helm, London.

Howell, S. N. G.; Webb, S. 1995. A guide to the birds of Mexico and northern Central America. Oxford University Press, Oxford.

Further web sources of information
View photos and videos, and hear sounds of this species from the Internet Bird Collection

Text account compilers
Isherwood, I., Mahood, S., O'Brien, A., Symes, A.

Contributors
Valdes, R.

IUCN Red List evaluators
Butchart, S., Taylor, J.

Recommended citation
BirdLife International (2013) Species factsheet: Vermivora crissalis. Downloaded from http://www.birdlife.org on 25/05/2013. Recommended citation for factsheets for more than one species: BirdLife International (2013) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 25/05/2013.

This information is based upon, and updates, the information published in BirdLife International (2000) Threatened birds of the world. Barcelona and Cambridge, UK: Lynx Edicions and BirdLife International, BirdLife International (2004) Threatened birds of the world 2004 CD-ROM and BirdLife International (2008) Threatened birds of the world 2008 CD-ROM. These sources provide the information for species accounts for the birds on the IUCN Red List.

To provide new information to update this factsheet or to correct any errors, please email BirdLife

To contribute to discussions on the evaluation of the IUCN Red List status of Globally Threatened Birds, please visit BirdLife's Globally Threatened Bird Forums.