Justification of Red List Category
This species is undergoing rapid declines in large parts of its range owing to a plethora of direct and indirect threats. It is consequently listed as Endangered.
The population is placed in the band 2,500-9,999 individuals, equating to 1,667-6,666 mature individuals, rounded here to 1,500-7,000 mature individuals. The population in Argentina was estimated in 2015 at c.500-600 individuals (A. Di Giacomo in litt. 2015). In Uruguay, the population is probably <1,000 individuals (Azpiroz et al. 2012). The population in Paraguay consists of 2,000-3,000 individuals, and in Brazil of < 10,000 individuals (Fraga and Sharpe 2019).
A rapid decline in the global population is suspected, as a number of factors continue to threaten all subpopulations. Recent extensive fieldwork in Argentina revealed a sharp decline in numbers of all known populations, increased fragmentation and isolation of subpopulations, and confirmed the loss of all known breeding colonies in the IBAs. Extensive fieldwork during 2013-2014 in Argentina showed a rapid increase in known threats. As a result of the analysis of this new data, a reduction in the species’s population size was estimated at 80.4% over three generations in Argentina (A. Di Giacomo in litt. 2015). In Uruguay, the species is listed as Vulnerable at the national level (A. Azpiroz in litt. 2017), and hence the population there is assumed to decline at 30-49% over three generations. The trend in Paraguay has not been quantified and is difficult to estimate; while the species colonizes new areas (R. M. Fraga in litt. 2018), it is feared that in the worst case the population may mirror the overall trend in Argentina and decline at up to 80.4% over three generations (R. P. Clay pers. comm.). In Brazil, the species is listed as Vulnerable under Criterion C at the national level, suggesting a rate of decline of 10-49% over three generations (MMA 2014). Taking the different population sizes in the respective countries into account, on the global scale the species would decline at a rate of roughly 30-79% over three generations. Considering the high number of threats that the species is facing, we can assume that the true rate of decline is closer to the higher end of the estimate.
Xanthopsar flavus has contracted its range in south Brazil (Santa Catarina and Rio Grande do Sul), south Paraguay (Hayes 1995, Ericson and Amarilla 1997, Clay et al. 1998, S. Centrón in litt. 2012), Uruguay (Azpiroz 2000) and north-east Argentina. There are now only local centres of abundance, but it was probably never abundant in Argentina (R. M. Fraga in litt. 2000). Breeding is often colonial, and only a small number of breeding sites have been discovered (Fonseca et al. 2004). In Paraguay, the population in the Aguapey and Tacuary watersheds in Itapúa and Misiones is estimated as c.1,500 birds, and the overall Paraguayan population as 2,000-3,000 individuals (Clay et al. 2003). In Argentina, there are disjunct populations totalling 500-600 individuals in north-east Corrientes (possibly continuous with populations in west Rio Grande do Sul) and south-east Entre Ríos (Fraga et al. 1998). In Uruguay, the main strongholds are in wetlands in the south and east, particularly at Bañados del Este (A. Azpiroz in litt. 2007). It has disappeared from a number of historical sites in recent years, but has also been found in some new areas, including Salto and Durazno (A. Azpiroz in litt. 2007, R. M. Fraga in litt. 2018).
In Entre Ríos, it occurs in agricultural land, breeding mainly in dry or upland terrain, with nests built in native herbaceous plants or introduced weeds (Fraga et al. 1998; R. P. Clay in litt. 1999, 2000; Fraga 2005). In Corrientes and Paraguay however, breeding only occurs in dense marsh vegetation, characterised by Eryngium, although feeding has been observed in rice-fields and grazed areas (Fraga et al. 1998; R. P. Clay in litt. 1999, 2000; Fraga 2005). In Brazil, its specific habitat is wetland surrounded by short grass, and it requires bare ground for foraging, the latter often the result of fire or trampling by cattle (Petry and Krüger 2010). Fire may be necessary in maintaining the grasslands of the Araucaria highlands (Petry and Krüger 2010). It may undertake irregular dispersive movements and can be highly mobile in the non-breeding season (Fraga et al. 1998). Breeding is generally colonial, although solitary nests have been found in Entre Ríos (Fraga 2005) as well as in Brazil and Uruguay (Azpiroz 2000). In Entre Ríos, breeding sites often fall within colonies of White-browed Blackbirds Leistes superciliaris. Breeding begins in September in Paraguay (R. P. Clay in litt. 1999, 2000) with eggs laid through to December, whilst in Uruguay and Argentina breeding has been reported in October-December (Azpiroz 2000, Fraga 2005). In Rio Grande do Sul, Brazil, breeding lasts from December-January (Dias and Maurício 2002). Nesting success was found to be generally rather low (Fraga et al. 1998, Azpiroz 2000, Dias and Maurício 2002, da Silva Mohr et al. 2017). During foraging, flocks follow Black-and-white Monjitas (Xolmis dominicanus), probably taking advantage of the sentinel behaviour of the latter (Krüger and Petry 2010).
The species has declined owing to a number of human impacts on grasslands, including stock-raising, cultivation, pesticides, burning, pine and eucalypt plantations, drainage and settlement (Pearman and Abadie 1995). In strongholds at Rio Grande do Sul, Brazil and Bañados del Este, Uruguay, the greatest threats are the damming of marshy valleys for irrigation (Dias and Maurício 2002, A. Azpiroz in litt. 2007), and high rates of nest failure owing to trampling by cattle (Fonseca et al. 2004). During the breeding season, the species is captured for the cage-bird trade (Fraga and Sharpe 2019). Brood-parasitism by Shiny Cowbird (Molothrus bonariensis) can be significant (Azpiroz 2000), particularly if populations are reduced by habitat loss (Fraga et al. 1998). In Paraguay, whole colonies have been destroyed by fire (R. P. Clay in litt. 1999, 2000). Conversion of marshes and seasonal inundated grasslands into rice and soy fields is an increasing threat in southern Paraguay. Already six of the 11 IBAs supporting this species are affected by rice cultivation. A recent analysis carried out in the breeding range of the species in southern Paraguay revealed that almost 70% of the suitable breeding habitat is covered by rice and soy fields (A. Lesterhuis and H. del Castillo in litt. 2007, H. del Castillo in litt. 2012). However, the species persists in cultivation where natural vegetation is left along rivers, and there are wetlands where birds can nest (H. del Castillo in litt. 2012). Particularly in Argentina, there is a rapid increase of known threats such as loss of breeding habitat by drainage of wetlands and marshes, intensification of forestation (i.e. pines and eucalyptus trees over grasslands), forest succession agriculture and livestock farming, increased risk of nest parasitism by M. bonariensis, bird trapping for trade, and lack of protected areas or other tools for providing protection for nesting sites (A. Di Giacomo in litt. 2015, 2018). Substantial parts of the species's habitat lack formal protection (A. Bosso in litt. 2017).
Conservation Actions Underway
CITES Appendix I. CMS Appendix I. This species is considered nationally Vulnerable in Brazil and Uruguay (Silveira and Straube 2008, Azpiroz et al. 2012, MMA 2014), and has recently been uplisted to Critically Endangered at the national level in Argentina (López-Lanús et al. 2008, Aves Argentinas and Secretaría de Ambiente y Desarrollo Sustentable de la Nación 2015). It is protected by law in Brazil, Uruguay and Paraguay, and occurs in at least one protected area in Brazil, two in Uruguay, and two in Paraguay. Since the species is highly mobile, it is difficult to designate sufficiently large reserves to provide adequate protection (Fraga et al. 1998). An experimental reintroduction of seven individuals from trade in Buenos Aires proved successful (Fraga 1999). A CMS Memorandum of Understanding targeting this and other southern South America grassland species has been recently approved by Argentina, Brazil, Paraguay and Uruguay. In 2015, Aves Argentinas started a volunteer Colony Guardian programme to guard nests and fledglings from predators and bird trappers (Anon. 2016).
18 cm. Striking, black-and-yellow marshbird. Male has bright golden-yellow head, lesser wing-coverts, rump and underparts. Black nape, upperparts, tail, and loral line. Slender black bill. Female has olive-brown crown and upperparts, streaked dusky. Dusky brown eye-stripe and auriculars. Yellow rump, lesser wing-coverts, eyebrow and underparts. Similar spp. Yellow-rumped Marshbird Pseudoleistes guirahuro and Brown-and-yellow Marshbird P. virescens are larger with uniformly brown head and breast. Voice Explosive and high-pitched song consisting of a short trill. Harsh tchep call. Hints Forages in flocks, often associating with Black-and-white Monjita Xolmis dominicana,as well as Yellow-rumped Marshbird and Brown-and-yellow Marshbird.
Text account compilers
Symes, A., Gilroy, J., Pople, R., Hermes, C., Sharpe, C.J.
Azpiroz, A., Bosso, A., Centrón, S., Clay, R.P., Di Giacomo, A., Fraga, R., King, J., Lesterhuis, A., Pereda, M., da Silva Mohr, L. & del Castillo, H.
BirdLife International (2021) Species factsheet: Xanthopsar flavus. Downloaded from http://www.birdlife.org on 25/10/2021. Recommended citation for factsheets for more than one species: BirdLife International (2021) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 25/10/2021.