Data Zone
Justification of Red List category
This species has undergone rapid population declines in the past. Recent information suggest that these declines may have stopped by now, but in the absence of further evidence to show a stable population, the species is conservatively retained as declining. Thus, as the rate of decline does not meet the threshold for Vulnerable anymore, the species has been downlisted to Near Threatened.
Population justification
The global population size is difficult to determine. Rosenberg et al. (2016) estimate the global population size to be 24,000 mature individuals. This number is based on an estimate of c.12,000 mature individuals in U.S.A. (Wilkins et al. 2006) and recent discoveries of high-density breeding populations in Mexico, which could mean that a doubling of the U.S.A. estimate may be appropriate (Rosenberg et al. 2016). It should be noted, though, that while Benson and Benson (1990) estimate c.6,300 ± 3,200 pairs in northern Coahuila, other estimates for Mexican populations have been very low. Wilkins et al. (2006) estimated only 259 males in Mexico, and Morrison and González-Rojas (2014) found only 341 individuals in three states of Mexico. Therefore, the global population size is here tentatively placed in the range 10,000-19,999 mature individuals. All individuals belong to the same subpopulation (Zink et al. 2010).
Trend justification
The species has been undergoing rapid declines in the past (J. Lyons in litt. 1999). However, it is unclear whether the species is still undergoing a decline (T. McFarland in litt. 2016). Following intense management programmes to reduce nest parasitism by Brown-headed Cowbirds (Molothrus ater), declines have slowed down and the species is showing signs of recovery (USFWS 2018a). There is no data available to assess the population trend from the North American Breeding Bird Survey (Sauer et al. 2017). As such, Partners in Flight also do not have a clear population trend estimate. Instead, Rosenberg et al. (2016) give a range within which the population reduction between 1970 and 2014 is suspected to fall. They propose that the reduction has been between 15-50% over this time period, which would roughly equate to a reduction of 4.5-18.0% over three generations (12.6 years), assuming a constant rate of decline. However, even though the species was previously thought to be declining rapidly, it is not clear whether it continues to decline (T. McFarland in litt. 2016), and so any population decrease over the past three generations could be even lower. In the absence of further evidence to show a stable population, the species is conservatively retained as declining.
This species once bred from Kansas through Oklahoma and Texas (U.S.A.) into central Coahuila, northwestern and southern Nuevo Leon and southwestern Tamaulipas (Mexico) (Contreras-Balderas et al. 2012, González-Rojas et al. 2014, J. I. González-Rojas in litt. 2016). Its breeding range has contracted though, and it is now thought to be absent from Kansas, and is only found in isolated patches in the Wichita Mountains in Oklahoma (Grzybowski 1995, T. McFarland in litt. 2016). In Texas, the species is known to occur in 57 counties, being more common in the western part of the state (McFarland et al. 2012). In the non-breeding season, it migrates to the west of Mexico along the Pacific coast, where it winters from Sinaloa to Oaxaca (Grzybowski 1995, Howell and Webb 1995, S. N. G. Howell in litt. 1998, Vega Rivera et al. 2011, Colón et al. 2015). Winter records from Sonora likely refer to individuals on migration (Powell 2013).
The species generally occurs in dense, dry deciduous shrubland maintained by disturbances, such as fire, in forest-grassland ecotone and in successional vegetation (Grzybowski 1995, Brewer 2018). Its habitat is dominated by densely foliated shrubs like Diospyros texana, Rhus virens and Sophora segundiflora and oaks (M. Lockwood in litt. 1999). In Oklahoma and Texas, it is found in deciduous and oak-juniper woodlands, but also in xeric thornscrub, while juveniles show a preference for riparian vegetation (Grzybowski 1995, Smith et al. 2012a, Dittmar 2014). In Mexico, it breeds in chaparral and submontane thornscrub at elevations of 920-2,000 m, but it may also use patches of suitable habitat within urban areas (Howell and Webb 1995, Contreras-Balderas et al. 2012, González-Rojas et al. 2014, J. I. González-Rojas in litt. 2016). Little is known of the species's migration routes. It likely migrates through the Sierra Madre Oriental and the Transvolcanic Mexican Belt, although further research is needed to confirm this (MacGregor-Fors et al. 2012, I. MacGregor-Fors in litt. 2016). The species winters in tropical dry forests and pine-oak forests from the lowlands up to 1,600 m, preferring tropical deciduous forest associated with rivers and streams (Howell and Webb 1995, Gonzalez-Medina et al. 2009, Colón et al. 2015). Wintering density in Sinaloa has been calculated to be 8 individuals per km2 (Gonzalez-Medina et al. 2009).
The species is threatened by several processes. Habitat loss and degradation are thought to be the key threats. Among these, fire suppression is probably the most serious threat, but also urban development, intensive grazing and browsing by livestock and native and introduced ungulates, and agricultural conversion have caused significant habitat loss in North America (Grzybowski 1995, J. Lyons in litt. 1999, USFWS 2018a). In the wintering range, habitat has been cleared for agriculture and grazing, reducing the potential suitable area or causing habitat fragmentation and declines in habitat quality (Miles et al. 2006, González-Medina et al. 2009). Further threats include brood parasitism. Brown-headed Cowbirds (Molothrus ater) inflict rates of parasitism of up to 100% at some sites (Grzybowski 1995, Farrell et al. 2011). Rates of nest predation as high as 50% in some locations have been reported. Snakes and birds are the primary predators of this species, with mammals, ants (e.g. fire ants Solenopsis spp.) and katydids also found to predate the species (Stake and Cimprich 2003, Campomizzi et al. 2009, Conkling et al. 2012, Smith et al. 2012b). Furthermore, habitat may be fragmented by the development of oil and gas pipelines as well as access corridors for windfarms (L. O'Donnell in litt. 2019). The high return rates of birds to breeding territories suggests few threats on the wintering grounds, even though less than 10% of the wintering area is protected (Grzybowski 1995, Vega Rivera et al. 2011, USFWS 2018a). Deforestation along the presumed migratory routes may potentially have a negative impact on the species (I. MacGregor-Fors in litt. 2016).
Conservation Actions Underway
Conservation actions are occurring on public and private land. Management programs to restore vegetation have occurred at various locations including Balcones Canyonlands National Wildlife Refuge, Fort Hood, Ker Wildlife Management Area and Wichita Mountains (Grzybowski 1995, Sexton 1997, Kostecke et al. 2005). On private land, conservation has occurred through various programs including Habitat Conservation Plans, Texas Parks and Wildlife Department’s Wildlife Management Plans, the Landowner Incentive Program, and the Leon River Restoration Project. Brown-headed Cowbirds are trapped to reduce brood-parasitism. Research is ongoing on breeding and wintering areas in Mexico and the USA. Modelling work on the species's migration is ongoing (I. MacGregor-Fors in litt. 2016). The species is included on the 'Watch List' of the State of North America's Birds as a species of high conservation concern (NABCI 2016). In the U.S.A., it was listed as endangered under the Endangered Species Act in 1987, but de-listed in 2018 following the recovery of the population (USFWS 2018b).
Conservation Actions Proposed
Monitor the population size and trend. Clarify the distribution in Mexico and estimate breeding numbers. Continue to study the species's migration routes (MacGregor-Fors et al. 2012) and identify important stopover sites (I. MacGregor-Fors in litt. 2016). Research the species's ability to adapt to habitat changes and urban environments (A. J. Contreras Balderas in litt. 2016). Investigate dispersal and survival of juveniles during migration and on wintering grounds (Dittmar 2014). Develop conservation actions through engagement with private landowners to balance conservation actions with other land uses. Assess threats on wintering grounds (J. Lyons in litt. 1999). Coordinate a range-wide action plan (J. A. Grzybowski in litt. 1999). Restore suitable habitat within the breeding range, including managing areas to promote dense deciduous cover for nesting (Bailey and Thompson 2007) and protect riparian vegetation (Dittmar 2014). Continue to manage cowbird populations, as research suggests that recovery of the species relies on such management (Campomizzi et al. 2013, Wilsey et al. 2013, T. McFarland in litt. 2016). Locate and protect wintering habitats, focusing primarily on sites linked to rivers and streams or fresh water resources in tropical dry forest.
12 cm. Well-marked and distinctive vireo. Male has black head, white lores and eye-ring (giving spectacled appearance), olive upperparts, blackish wings fringed olive and two yellowish wing-bars. Whitish underparts with olive flanks. Red iris. Female duller and with grey head. Juvenile browner. Similar spp. Cassin's Vireo V. cassinii differs from female in larger size and bill, and lacks red iris. Voice Song a series of rapid 2-3 note phrases. Call a dry chit-it.
Text account compilers
Isherwood, I., Derhé, M., Pople, R., Sharpe, C.J., Wheatley, H., Ashpole, J, Bird, J., Westrip, J., Harding, M., Wege, D., Hermes, C.
Contributors
Campomizzi, A.J., Colón, M., Contreras Balderas, A.J., Farquhar, C., González Rojas, J.I., González-Medina, E., Grzybowski, J., Howell, S., Lockwood, M., Lyons, J., MacGregor-Fors, I., McFarland, T., O'Donnell, L. & Wauer, R.
Recommended citation
BirdLife International (2024) Species factsheet: Black-capped Vireo Vireo atricapilla. Downloaded from
https://datazone.birdlife.org/species/factsheet/black-capped-vireo-vireo-atricapilla on 23/11/2024.
Recommended citation for factsheets for more than one species: BirdLife International (2024) IUCN Red List for birds. Downloaded from
https://datazone.birdlife.org/species/search on 23/11/2024.