• Summary
• Text account
• Data table and detailed info
• Distribution map
• Reference and further resources

Justification of Red List category
The population size of this species is suspected to be small. Based on evidence suggesting that there is some movement between the southern part of the range and the northern part, it is assumed that the species forms just one subpopulation within its naturally fragmented habitat. Declines are ongoing, particularly in Peru, where habitat is lost and degraded for agriculture and settlements. The species is therefore listed as Near Threatened. The status should be carefully monitored, particularly in Peru where further habitat loss could result in a rapid increase in threat status.

Population justification
The global population size has not been quantified. The national population in Peru is estimated at less than 1,000 individuals (SERFOR 2018); assuming that around 2/3 of the population are mature this equates to roughly 670 mature individuals. There are no population size estimates available for Chile. The species appears local and less common in Peru, but fairly common in Chile (Jaramillo 2020). Based on this, and on observational records from eBird (2021), the national population in Chile may at most be twice the size of the population in Peru and is therefore tentatively suspected to number up to 2,000 mature individuals, roughly equating to 1,330 mature individuals. This number however requires confirmation. Based on these values, the global population is preliminarily inferred to number up to 2,000 mature individuals. To account for uncertainty, it is here placed in the band 1,000-2,499 mature individuals.
The subpopulation structure has not been formally assessed. However, it is assumed that the northern part of the distribution range acts as a population sink with individuals from southern Peru and Chile moving into the area (SERFOR 2018). Based on this, the population is assessed as forming one subpopulation.

Trend justification
Population trends differ across the range. The population is declining particularly in Peru, where the species has become rare and local owing to habitat loss and degradation (SERFOR 2018; Jaramillo 2020). The conversion of riparian thickets and shrubs to agricultural fields and settlements make the zone unsuitable for the species, as it does not occur in open or ubranised areas (Jaramillo 2020). This decline is partly alleviated by local increases and a range expansion in Chile (Jaramillo 2020). Precautionarily the overall population is inferred to be in decline as its habitat, and with it the Area of Occupancy, are shrinking in the north of the range. The rate of decline has not been quantified, but is unlikely to exceed 10% over ten years.

Xenospingus concolor occurs in 15 scattered river valleys or habitat patches on the Pacific slope of Peru (Lima, Ica, Arequipa and Moquagua) and north Chile (Tarapacá and Antofagasta) (Howell and Webb 1995, O. González in litt. 1999, Clements and Shany 2001). The range has contracted in Peru, and remaining populations are fragmented (González and Málaga 1997), with no recent records less than 70 km south of Lima city (Clements and Shany 2001). Key populations in Peru are at Ocucaje (Ica), the Yauca valley and near the Mejia lagoons in the Tambo valley (both Arequipa) (González and La Torre-Cuadros 2001). In Chile, it is common in the Lluta and Azapa valleys (S. N. G. Howell in litt. 1999), with several subpopulations exceeding 1,000 individuals, and it has colonised a new area in Antofagasta (Howell and Webb 1995), having not been seen in the province since 1944. Recent information suggests that it is probably more common than previously estimated, at least in Chile (G. Engblom in litt. 2003). The range extension south to Antofagasta may have been related to the planting of ornamental shade trees (Howell and Webb 1995).

It occurs in areas supporting growth of trees of the genus Prosopis, dense riparian thickets, and also uses olive groves and areas with Arundo donax and Tessaria (e.g. at Cañete valley). However, these habitats may only be used if remnant native habitat is also present in the surroundings (O. González in litt. 2004). It is found mostly at low elevations from sea level to 500 m, but has been recorded to 1,900 m in Peru and to 2,500 m in Chile, and may be vagrant to 3,500 m (Jaramillo 2020). The diet consists of insects, seeds or fruit. Two nests have been found, one under construction in Tessaria integrifolia and Baccharis in December, and one recently abandoned in Baccharis, Acacia macracantha and introduced Tamarix in June (González 1997). The species was observed nesting in small patches of Prosopis, where the surrounding habitat has been degraded (Aguilar and González 2010).

Intensive irrigation and cultivation (e.g. for cereals and cotton) have reduced riparian thickets to narrow and fragmented strips, particularly in Peru where suitable habitat has reduced considerably (SERFOR 2018; Jaramillo 2020). The species depends on a dense shrubbery layer and is not found in fully cleared, converted habitat (Jaramillo 2020). Rapid declines could result from further changes in land-use at sites where the species is common. Cutting of Prosopis trees in Ica is prohibited, but illegal cutting continues in many areas (O. González in litt. 1999, 2004).

Conservation Actions Underway
The species occurs in the Mejía Lagoons National Sanctuary and Bosque de Protección Nuevo Imperial, Peru. Landowners have agreed to preserve habitat in Ocucaje, the Yauca valley and at Mejía lagoons, Peru (González and La Torre-Cuadros 2001).

Conservation Actions Proposed
Quantify the population size, particularly in the Chilean part of the range. Conduct repeated surveys of known sites, as well as potentially suitable surrounding areas, in order to monitor population trends. Determine rates of range contraction. Conduct detailed ecological studies to determine whether it is genuinely tolerant of secondary habitats, particularly in the absence of adjacent primary habitat patches. Campaign for stronger enforcement of laws banning the cutting of Prosopis trees in Peru. Engage key landowners in the development of site management plans and sustainable development programmes (O. González in litt. 1999). Plant and encourage regeneration of trees to protect rivers in the dry valleys of coastal south Peru (T. Valqui in litt. 1999). Develop a legal framework for the establishment of private reserves in Peru and their incorporation in the national protected areas system (O. González in litt. 1999).

15 cm. Distinctive finch. Uniform plumbeous above with black loral area. Paler grey below with whitish belly. Long tail. Bright yellow bill and legs. Immature is olivaceous-brown above, yellowish-buff below with brownish streaking. Two indistinct, buffy wing-bars. Brownish bill. Similar spp. Plumbeous Sierra-finch Phrygilus unicolor lacks yellow bill and legs. Female Blue-black Grassquit Volatinia jacarina is considerably smaller and shorter-tailed. Voice Jumbled warbling song and sharp zeep call.

Text account compilers
Hermes, C.

Contributors
Butchart, S., Engblom, G., Gilroy, J., Gonzalez, O., Howell, S., Sharpe, C.J. & Valqui, T.

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Recommended citation
BirdLife International (2024) Species factsheet: Slender-billed Finch Xenospingus concolor. Downloaded from https://datazone.birdlife.org/species/factsheet/slender-billed-finch-xenospingus-concolor 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.