Justification of Red List Category
This species's population size is thought to be declining rapidly as a result of landscape conversion for agriculture. The species is therefore listed as Vulnerable.
In Argentina, surveys in southwest Buenos Aires and adjacent areas of La Pampa in 1992-1996 produced an estimated population size of 7,500 individuals (approximately equivalent to 5,000 mature individuals; Tubaro and Gabelli 1993, 1999). Less than 29% of apparently suitable sites were occupied by the species. The species's extent of occurrence was estimated to be approximately 8,000 km2 (Tubaro and Gabelli 1999). More extensive surveys in the same region in 1999 produced a population size estimate of at least 28,000 individuals (approximately equivalent to 18,667 mature individuals) and an extent of occurrence of 4,810km2, indicating a range contraction of c.30% since 1992-1996 (Gabelli et al. 2004). The higher population estimate was attributed to a greater sampling effort than that used in the previous study. More recently, the Argentinian national Red List states that the estimate by Gabelli et al. (2004) was likely an overestimate, and that surveys in 2011-2014 found a population size 10% smaller than that estimated in 1992-1996 (MAyDS and Aves Argentinas 2017), which would equate to a population size of 6,750 individuals, or approximately 4,500 mature individuals. The population in Argentina in 2017 was considered to be smaller than 2,500 mature individuals (MAyDS and Aves Argentinas 2017), but the basis of this figure was not provided. The current population size in Argentina is therefore estimated to fall within the band 4,000-5,000 mature individuals.
In Uruguay, surveys in the Arerunguá region, Salto, and surrounding areas in 2003 estimated a regional population of 78-90 pairs (equivalent to 156-180 mature individuals; Azpiroz 2005). Subsequent studies revised this figure to c.150-200 pairs (equivalent to 300-400 mature individuals) in 2012 (Azpiroz and Cozzani 2017). A further population of 50-70 individuals (equivalent to 33-47 mature individuals) was recently discovered in Tacuarembó (Azpiroz and Cozzani 2017). However, during the 2016 breeding season, only five breeding pairs were recorded in the Arerunguá area, in an area thought to have contained 100-140 pairs in the last decade (Azpiroz and Cozzani 2017). During the 2017 breeding season, 5-20 pairs (approximately equivalent to 10-40 mature individuals), plus a post-breeding group of around 120 individuals (many of which were juveniles) were recorded in the area (Azpiroz and Cozzani 2017). The population size in Uruguay is therefore likely to fall within the band 50-200 mature individuals. The global population size is therefore placed in the range 4,000-6,000 mature individuals.
In Argentina, population densities were estimated to be 50 individuals per km2 (C.I. 20-126) in natural grasslands in the southwest of the surveyed region, and 4 individuals per km2 (C. I. 0.8-22) in the northeast (Gabelli et al. 2004). Surveys of grasslands and cultivated areas in Uruguay in 2004-2005 recorded mean population densities of 13.6 individuals per km2 (C. I. 5.4-34.3) in grasslands grazed by cattle and sheep, and 1.5 individuals per km2 (C. I. 0.4-5.8) in grasslands grazed by cattle and Pampas Deer (Azpiroz and Blake 2009). Pretelli et al. (2013) estimated a density of 5 individuals per km2 of wintering individuals, during surveys of Cortaderia selloana grasslands in the south-east Pampas region, Argentina.
The subpopulations in Bahia Blanca (Argentina) and Arerungua (Uruguay) are around 900 km apart. A study of the species's genetics estimated than an average of 2.57 individuals migrate between the two subpopulations per year, and that the two populations have four genetic clusters: two in the Arerungua population, one in the Bahia Blanca population, and another shared between the two (Repetto 2017). There are therefore considered to be 1-4 subpopulations.
Recent estimates for the population size in Argentina have included: c.7,500 individuals (equivalent to 5,000 mature individuals) in 1992-1996 (Tubaro and Gabelli 1999) and 28,000 individuals (equivalent to 18,667 mature individuals) in 1999 (Gabelli et al. 2004). The species's extent of occurrence in Argentina was also found to have contracted by 30% between 1993-1996 and 1999 (Gabelli et al. 2004), which would equate to a reduction of 55% over ten years. However, the Argentinian Red List (MAyDS and Aves Argentina 2017) states that the 1999 population estimate was an overestimate, and that surveys in 2011-2014 have found a population size 10% smaller than that estimated in 1992-1996, which would approximately equate to 4,500 mature individuals. This rate of decline would equate to a reduction of 5.5% over ten years, assuming the 1992-1995 estimate was accurate, or a 64% reduction over ten years if the 1999 population estimate was correct. The Argentinian Red List also states that the current population in Argentina is less than 2,500 mature individuals, but the basis of this estimate is not described (MAyDS and Aves Argentina 2017).
In the Arerunguá area in Uruguay, there were an estimated 300-400 mature individuals in 2012 (Azpiroz and Cozzani 2017). A further population of 50-70 individuals (equivalent to 33-47 mature individuals) was recently discovered in Tacuarembó (Azpiroz and Cozzani 2017). However, during the 2016 breeding season, only five breeding pairs were recorded in the Arerunguá area, in an area thought to have contained 100-140 pairs in the last decade (Azpiroz and Cozzani 2017). During the 2017 breeding season, 5-20 pairs, plus a post-breeding group of around 120 individuals (many of which were juveniles) were recorded in the area (Azpiroz and Cozzani 2017). Assuming the population size declined from 300-450 mature individuals in 2012, to 50-200 mature individuals in 2017, this rate of decline would equate to a reduction of between 56% and 99% over ten years.
Based on the evidence described, the species is inferred to have undergone an overall reduction of between 9% and 69% across the past ten years, with the best estimate tentatively placed in the band 30-49%. Current trends are assumed to continue over the next decade.
Leistes defilippii is restricted to northern and central Uruguay, and central eastern Argentina. In Argentina, the only confirmed remaining population is found in SW Buenos Aires and eastern La Pampa (MAyDS and Aves Argentinas 2017), with the largest population in the region of Bahia Blanca, and there have been a few recent scattered records in San Luis and Corrientes provinces (Azpiroz et al. 2012), and two small groups recorded in eastern Buenos Aires that may have been wintering individuals (Pretelli et al. 2013). In Uruguay, most recent records are concentrated in Arerungua in the southeast of Salto and surrounding regions of Paysandú, and in the southwest of Tacuarembó (Azpiroz and Cozzani 2017).
It was formerly common and widespread in east-central Argentina and Uruguay (Cotinga 1995, Azpiroz 2005), and rare in south Brazil (two historic winter records from Rio Grande do Sul, and possible records from Paraná and Santa Catarina). There are no recent records from Brazil and the species is considered nationally extinct (MMA 2014).
Since 1900, its range has decreased by 90%, with most of this decline occurring between 1900 and 1950 (Tubaro et al.1994, Tubaro and Gabelli 1999). In 1992-1993, the extent of occurrence in Argentina was estimated at 8,000 km2 and the area of occupancy at less than 150 km2 (Tubaro and Gabelli 1999). In 2004, a more detailed study estimated the extent of occurrence in Argentina at 4,810 km2, and hence a range contraction of 30% within 10 years, with an area of occupancy of 517 km2 (Gabelli et al. 2004). These are concentrated in south-west Buenos Aires and adjacent La Pampa, with records in Entre Ríos, San Luis, Córdoba and Corrientes (Tubaro and Gabelli 1999, R. Fraga in litt. 2012).
It inhabits natural grasslands (vegetation height of 29-45 cm) dominated by Stipa spp., including land abandoned for at least five years (Tubaro and Gabelli 1993, 1999, Tubaro et al. 1994, Cozzani et al. 2004). Some birds breed and winter in planted pastures and cultivated fields with a similar vegetation structure (Tubaro and Gabelli 1999, Gabelli et al. 2004). However, a study in Buenos Aires province found that 90% of reproductive groups were present in natural grasslands with high vegetation cover (Fernandez et al. 2004). It can coexist with cattle, but apparently avoids planted pasture, as well as areas where grazing is more intensive and vegetation height is consequently lower (Tubaro and Gabelli 1999). Maintenance of moderate grazing regimes appears to favour the species (Zalba et al. 2008). In eastern Buenos Aires, wintering individuals were recorded in small patches of Cortaderia selloana within and agricultural matrix (Pretelli et al. 2013). Although it is currently resticted to a lowlands, this is thought to be a by-product of the species's range retraction, as there have been historical records at higher altitudes (Tubaro and Gabelli 1999, Fernandez et al. 2004). The diet includes seeds, insects and shoots. The species is gregarious thoughout the year, with breeding territories packed together in groups (Tubaro and Gabelli 1999). Breeding occurs between mid-October and November, and 3-4 eggs are laid (Azpiroz 2005) in nests on the ground, concealed under grasses (Tubaro and Gabelli 1999). It forms large flocks outside the breeding season (Tubaro and Gabelli 1999). There is some northwards movement in winter, but it is primarily resident (Tubaro and Gabelli 1999).
Rapid and widespread conversion to sown pastures for cattle-ranching, arable agriculture (mainly soybean, sunflower, maize, wheat and rice) and tree plantations (pine and eucalyptus) are primarily responsible for long-term declines. Although the species can coexist with cattle, it does not tolerate intensive grazing (Tubaro and Gabelli 1999). Between 1985-1989 and 2002-2004, grassland cover within the Río de la Plata grassland region decreased from 67.4 to 61.4% and the area of agriculture increased from 22 to 25.9%, with declines in grassland being higher in Argentina, and some areas of flat pampas dominated by arable plantations (Baldi and Paruelo 2008). Much of the remaining natural grasslands in the region are now highly fragmented. The species is now restricted to areas least suitable for agriculture, although the rate of grassland conversion within occupied areas continues to outstrip the rate of grassland regeneration (Gabelli et al. 2004). Urban development and development for tourism also pose a threat in some regions (Pretelli et al. 2013). In Uruguay, there are plans to install a new pulp mill, which may put further pressure on the natural grasslands in the Arerunguá region (Azpiroz and Cozzani 2017). The development of wind farms in Buenos Aires province could pose a further threat (H. Ibáñez in litt. 2020).
Other factors may interact with habitat loss, including high rates of nest predation (Cozzani et al. 2004), although recent studies in Uruguay suggest that this may have only a limited effect (A. Azpiroz in litt. 2007). Trampling by cattle (Gabelli et al. 2004), and brood parasitism by Shiny Cowbird Molothrus bonariensis (Cozzani et al. 2004, Gabelli et al. 2004) could also influence productivity, although parasitism appears to be rare (Gochfeld 1979, Cozzani et al. 2004, Azpiroz 2015). Competition with Long-tailed Meadowlark L. loyca and White-browed Blackbird L. superciliaris could negatively influence this species (Tubaro and Gabelli 1999), although studies have found no evidence that presence of either species affects site selection (Gabelli et al. 2004, Fernandez et al. 2004). Capture for trade is not currently extensive (Tubaro and Gabelli 1999), but in 1988 over 100 birds were seen in local markets (Bertonatti and Tubaro 1993).
Conservation Actions Underway
It is protected under Brazilian and Uruguayan law and from trapping in Argentina. Studies have clarified its distribution, numbers and habitat requirements (Tubaro et al. 1994, Tubaro and Gabelli 1999, Fernandez et al. 2004, Gabelli et al. 2004, Azpiroz 2005).
In northern Uruguay, educational visits to schools were carried out in association with surveying in 2003 (Azpiroz 2005). In Uruguay, there has been promotion of agricultural practices that benefit the species (Apiroz 2012), but the scheme was suspended (Azpiroz and Cozzani 2017). Educational material has been produced for farmers. The Southern Cone Grasslands Alliance was established in 2006 to promote sustainable ranching practices across the region, and a certification scheme has been developed to provide a financial incentive for sustainably-produced beef (Azpiroz 2012). The Arerungua region has been designated as a Priority Area, and sustainable management practices have been promoted, with incentives provided through a certification scheme and ecotourism (Repetto 2017).
21 cm. Striking icterid. Male upperparts and most underparts black, edged brown. Bright red supraloral stripe, throat and breast. Cream eyebrow. Black underwing-coverts. Female much browner and more streaked, with pinky-red centre to belly and buffy throat. Similar spp. Long-tailed Meadowlark S. loyca has pale underwing-coverts, longer tail, and browner coloration. White-browed Blackbird Leistes superciliaris has much shorter bill. Voice Short, buzzy series of high-pitched notes. Dull, raspy jzeet call.
Text account compilers
Azpiroz, A., Fraga, R., Gilroy, J., Harding, M., Khwaja, N., Pople, R. & Sharpe, C.J.
BirdLife International (2021) Species factsheet: Leistes defilippii. Downloaded from http://www.birdlife.org on 21/10/2021. Recommended citation for factsheets for more than one species: BirdLife International (2021) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 21/10/2021.