email a friend
printable version
VU
Nava's Wren Hylorchilus navai

Justification
This species qualifies as Vulnerable owing to its small and declining range. The size of the range is small enough to qualify as Endangered, but it is only Vulnerable because recent surveys have found the species at nine locations. If it is found at more locations and estimated to have a larger population, the species is likely to be downlisted to Near Threatened.

Taxonomic source(s)
AOU. 1998. Check-list of North American birds. American Ornithologists' Union, Washington, D.C.

Taxonomic note
Hylorchilus sumichrasti (Sibley and Monroe 1990, 1993) has been split into H. sumichrasti and H. navai following AOU (1998).

Identification
16 cm. Long-billed, brown-and-white wren. Long blackish bill, orange basally on lower mandible. Grey lores. Rich brown upperparts, barred lightly black on wings. Whitish throat and upper breast becoming grey on lower breast. Faint, dusky scalloping on chest. Dark sooty-brown on sides and flanks. Dusky grey-brown undertail-coverts. White scallops on belly with dark subterminal crescents. Voice Thin nasal iihn in steady series or pairs.

Distribution and population
Hylorchilus navai has a restricted range in easternmost Veracruz (six sites in the Uxpanapa region, at the mid-point of the Isthmus of Tehuantepec), with records from one site in west Chiapas, and two in east Oaxaca, south Mexico (Gomez de Silva 1997). The total extent of its range was initially estimated at 4,800-4,900 km2, within which it is fairly common but local (Howell and Webb 1995a, Gomez de Silva 1997). However, further mapping indicates that the known range is likely to be considerably smaller. In 1992, a crude density estimate of c.20 birds/km2 was calculated at El Ocote in Chiapas (Atkinson et al. 1993).

Population justification
The population is estimated to number 2,500-9,999 individuals based on an assessment of known records, descriptions of abundance and range size. This is consistent with recorded population density estimates for congeners or close relatives with a similar body size, and the fact that only a proportion of the estimated Extent of Occurrence is likely to be occupied. This estimate is equivalent to 1,667-6,666 mature individuals, rounded here to 1,500-7,000 mature individuals.

Trend justification
There are no new data on population trends; however, the species is suspected to be suffering a slow decline, owing to habitat degradation.

Ecology
It is restricted to limestone outcrops in the shade of primary lowland evergreen forest, mainly at 75-800 m (Atkinson et al. 1993, Howell and Webb 1995a, Gomez de Silva 1997). This habitat is naturally patchy, with outcrops occurring every c.4 km2 in the west and central parts of the Uxpanapa region (Gomez de Silva 1997). Fortunately, it seems able to survive in patches of forest as small as 8 ha (Gomez de Silva 1997). It gleans invertebrates from the lichen-covered surface of the limestone and in the cracks and crevices of boulders (Atkinson et al. 1993).

Threats
Settlement and cattle-ranching following road-building have fragmented forests within its range (Atkinson et al. 1993). Although limestone outcrops are generally not suitable for ranching, deforestation has left them isolated and threatened by firewood extraction (Atkinson et al. 1993, Gomez de Silva 1997). This has important implications since such small birds with rounded wings are (predictably) poor dispersers (Atkinson et al. 1993, Gomez de Silva 1997).

Conservation Actions Underway
It occurs in Selva El Ocote Special Biosphere Reserve, but there is very little suitable habitat within this protected area (Gomez de Silva 1997). An important area of habitat is within the proposed Chimalapas-Uxpanapa Biosphere Reserve (Whittingham and Atkinson 1996). Conservation Actions Proposed
Survey "islands" of habitat between Selva El Ocote and the Cañon de Sumidero (J. Morales-Pérez in litt. 1998). Formally designate the proposed Chimalapas-Uxpanapa Biosphere Reserve (Whittingham and Atkinson 1996).

References
Atkinson, P. W.; Whittingham, M. J.; Gómez de Silva Garza, H.; Kent, A. M.; Maier, R. T. 1993. Notes on the ecology, conservation and taxonomic status of Hylorchilus wrens. Bird Conservation International 3: 75-85.

Collar, N. J.; Gonzaga, L. P.; Krabbe, N.; Madroño Nieto, A.; Naranjo, L. G.; Parker, T. A.; Wege, D. C. 1992. Threatened birds of the Americas: the ICBP/IUCN Red Data Book. International Council for Bird Preservation, Cambridge, U.K.

Gómez de Silva, H. 1997. Comparative analysis of the vocalizations of Hylorchilus wrens. Condor 99: 981-984.

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

Whittingham, M. J.; Atkinson, P. W. 1996. A species split in Mexico: Sumichrast's and Nava's Wren Hylorchilus sumichrasti and H. navai. Cotinga: 20-22.

Text account compilers
Capper, D., Isherwood, I., Mahood, S., Pople, R., Sharpe, C J

Contributors
Morales, J.

IUCN Red List evaluators
Butchart, S., Symes, A.

Recommended citation
BirdLife International (2014) Species factsheet: Hylorchilus navai. Downloaded from http://www.birdlife.org on 17/04/2014. Recommended citation for factsheets for more than one species: BirdLife International (2014) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 17/04/2014.

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.

Additional resources for this species

ARKive species - Nava's wren (Hylorchilus navai) 0

Key facts
Current IUCN Red List category Vulnerable
Family Troglodytidae (Wrens)
Species name author Crossin & Ely, 1973
Population size 1500-7000 mature individuals
Population trend Decreasing
Distribution size (breeding/resident) 430 km2
Country endemic? Yes
Links to further information
- Additional Information on this species