Justification of Red List Category
A re-assessment of the species's extent of occurrence using a Minimum Convex Polygon means it no longer meets the threshold for Endangered. The species does still occupy an area within which suitable habitat is severely fragmented, and it has recently been extirpated from at least two sites. Rapid declines are suspected in the species's range and population owing to continued habitat loss and degradation, and hence the species is now listed as Vulnerable.
The current known population includes important concentrations at Punta San Pedro (70 birds), Todos Santos (120 individuals) Santiago (up to 150 birds) and San José del Cabo (487-700 adults in 2009) (Pronatura in litt. 2009, B. Matheson in litt. 2013, R. Rodríguez-Estrella in litt. 2016). Although the total population size has not been precisely estimated, it is best placed in the band 1,000-2,499 mature individuals. This equates to 1,500-3,749 individuals in total, rounded here to 1,500-4,000 individuals.
This species is suspected to be undergoing a rapid population decline owing to pressures on Baja California's oases and the resultant conversion of habitat at many sites.
Geothlypis beldingi has a fragmented distribution on the Baja California peninsula, Mexico. The nominate race is known from at least 15 sites (C. Devenish in litt. 2010) with important concentrations of 70 birds at Punta San Pedro, >100 or c.120 birds at Todos Santos (B. Matheson in litt. 2016) R. Rodríguez-Estrella in litt. 2016), ?150 birds at Santiago (R. Rodríguez-Estrella in litt. 2016), and at San José del Cabo the population increased to 487-700 mature individuals probably related to a chance increase in the quality of habitat (Pronatura in litt. 2009). The race goldmani is now known from at least 12 sites including large numbers at San Ignacio (537-648 birds) and La Purísima (Rodríguez-Estrella et al. 1999, Erickson et al. 2008). However, despite being relatively common at these site, the area of suitable habitat is probably very restricted (Rodríguez-Estrella et al. 1999). It appears to have been extirpated from at least two sites, El Triunfo and San Pedro de la Presa (Erickson et al. 2008, R. Rodríguez-Estrella in litt. 2016); but, in 2009 up to three adults were present at El Oro. This might be the location referred to as El Triunfo, where the species was collected in 1924 (C. Devenish in litt. 2010). Another small breeding population was recently found at Las Cuevas (Erickson et al. 2008) and San Dionisio (Pronatura in litt. 2009), near Santiago.
It occupies oases of reeds, cattails and tule, fringing permanent, lowland, freshwater marshes or rivers, and has been found occasionally in brackish coastal marshes (Curson et al. 1994), and recently in at least one newly created marsh in a hotel district, near active agriculture (Erickson et al. 2008). Birds are mostly located within 15 m of the water's edge, and never more than 50 m from water (Rodríguez-Estrella et al. 1999). The nest is up to 1.5 m above the ground, in cattails or tule, and eggs are laid between March and May (Curson et al. 1994). Birds have been recorded c.200 km from the known breeding range suggesting it is capable of dispersing over reasonably large distances (Erickson 2006).
The oases of Baja California are under high human pressure, especially in the south. Accidental and induced fires, reed-cutting for tourism facilities and house construction, and drainage for agriculture and cattle-ranching have decreased suitable habitat (Rodríguez-Estrella et al. 1999). Such apparently isolated and disjunct populations are probably vulnerable to stochastic events, with hurricanes frequently eliminating portions of reedgrass vegetation in August-October (Rodríguez-Estrella et al. 1999); however, this may underestimate the species's dispersal capabilities (Erickson et al. 2008), which might make it more resilient to such threats.
Conservation Actions Underway
Recent surveys have improved knowledge of the species's distribution (Rodríguez-Estrella et al. 1999, Erickson et al. 2008, Pronatura in litt. 2009). The IBA Estero de San José del Cabo, a 42 ha freshwater coastal lagoon at the southern tip of the peninsula of Baja California, incorporates habitat for Belding's Yellowthroat, and was designated as a RAMSAR site in February 2008. Angeles del Estero and Agrupación Ciudadana Ecologista, two small local NGOs in the adjacent town of San José del Cabo, have a history of involvement in the conservation of the IBA. The inclusion of oases in Ordenamiento Ecológico Territorial of SEMARNAT in Mexico provides them with official protection in Baja California Sur state and municipalities that can aid in the protection of this species (R. Rodríguez-Estrella in litt. 2016). As part of the BirdLife International Preventing Extinctions Programme, Species Guardian Pronatura Noroeste are implementing the following actions (C. Devenish in litt. 2010): a conservation area plan for the Estero de San José del Cabo was developed to identify conservation targets, assess the viability of these targets, identify critical threats and develop conservation strategies; research and monitoring is underway to determine current status and threats in the Estero de San José del Cabo Ecological Reserve, and at other sites historically important for the species; clean-up days have been conducted; educational sign boards were erected at the San José del Cabo reserve; two bird festivals have been held and outreach materials have been distributed to local schools, and local bird guides are being trained (86 by the end of 2009) to raise the species's profile and strengthen livelihood links with its conservation. A conservation action plan was published in 2011 (Palacios and Galindo-Espinosa 2011).
Conservation Actions Proposed
Use standardised survey techniques to survey all potential nesting habitat in Baja California Sur and adjacent south-eastern Baja California, identifying potential new locations using satellite imaging. Conduct a thorough census of each site by counting singing males in spring in order to ascertain the current population, and repeat at regular intervals to detect local and regional trends. Conduct a formal dispersal study in order to design long-term management actions for the Belding's Yellowthroat metapopulation system. Undertake genetic studies to address questions concerning such issues as the validity of recognising two subspecies or the genetic consequences of population patchiness and potential bottlenecks (Erickson et al. 2008). Incorporate marsh creation into plans for the development of golf courses and resorts within this species's range (Erickson 2006, Erickson et al. 2008). Prohibit burning and cutting of the water-edge vegetation at all sites (Rodríguez-Estrella et al. 1999). Initiate a public awareness programme. Promote bird tourism to generate income for protecting key sites. Increase the capacity of San José del Cabo in water treatment and quality monitoring. Ensure an adequate supply of water to the oasis at San José del Cabo through water rights. Implement an education and outreach programme on the importance and environmental services of the watershed at San José del Cabo. Promote better cattle ranching practices and law enforcement (C. Devenish in litt. 2010).
14 cm. Yellow-olive, masked bird. Yellow-olive upperparts and crown with narrow sulphur fringe bordering black mask. Bright yellow underparts, washed ochraceous on flanks. Female lacks mask and has olive head with pale eye-ring and pale buff supercilium. Yellow underparts, washed brown on flanks and becoming white on belly. Pinkish legs. Black bill. Subspecies goldmani is duller overall with more olive upperparts and brownish wash on flanks. Border behind mask is more whitish in males. Similar spp. Common Yellowthroat G. trichas is smaller with pink on lower mandible. Males have grey border to mask (some G. trichas can have yellow border). Females duller with more indistinct facial pattern. Voice Song is rich, powerful series of phrases. Harsh tchech call.
Text account compilers
Calvert, R., Symes, A., Taylor, J., Pople, R., Khwaja, N., Sharpe, C.J., Bird, J., Isherwood, I., Westrip, J., Capper, D.
Rodríguez-Estrella, R., Devenish, C., Matheson, B., Howell, S.
BirdLife International (2020) Species factsheet: Geothlypis beldingi. Downloaded from http://www.birdlife.org on 08/08/2020. Recommended citation for factsheets for more than one species: BirdLife International (2020) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 08/08/2020.