VU
Sickle-winged Nightjar Eleothreptus anomalus



Taxonomy

Taxonomic source(s)
del Hoyo, J., Collar, N.J., Christie, D.A., Elliott, A. and Fishpool, L.D.C. 2014. HBW and BirdLife International Illustrated Checklist of the Birds of the World. Volume 1: Non-passerines. Lynx Edicions BirdLife International, Barcelona, Spain and Cambridge, UK.
SACC. 2005 and updates. A classification of the bird species of South America. Available at: https://www.museum.lsu.edu/~Remsen/SACCBaseline.htm.

IUCN Red List criteria met and history
Red List criteria met
Critically Endangered Endangered Vulnerable
- - A3c+4c

Red List history
Year Category Criteria
2021 Vulnerable A3c+4c
2016 Near Threatened A2c+3c+4c;C1
2012 Near Threatened A2c+3c+4c;C1
2008 Near Threatened A2c; A3c; A4c; C1
2004 Near Threatened
2000 Lower Risk/Near Threatened
1994 Lower Risk/Near Threatened
1988 Threatened
Species attributes

Migratory status unknown Forest dependency low
Land-mass type continent
Average mass -
Range

Estimate Data quality
Extent of Occurrence (breeding/resident) 1,490,000 km2 medium
Severely fragmented? no -
Population
Estimate Data quality Derivation Year of estimate
Population size unknown poor suspected 2021
Population trend decreasing poor inferred 2020-2030
Rate of change over the past 10 years/3 generations (longer of the two periods) 10-19% - - -
Rate of change over the future 10 years/3 generations (longer of the two periods) 10-49% - - -
Rate of change over the past & future 10 years/3 generations (longer of the two periods) 10-49% - - -
Generation length 3.32 years - - -
Percentage of mature individuals in largest subpopulation 1-89% - - -

Population justification: It appears to be scarce and localised (Pearman and Abadie 1995). Almost all records are of lone individuals, although six individuals were recorded at a wetland site in Rio Grande do Sul (Accordi 2002), the species is observed daily at Reserva Natural Rincón de Santa María, Corrientes (Fariña et al. 2018, Bodrati et al. 2019), and there are known populations at Campo San Juan, Misiones, and possibly at Reserva Natural Provincial Iberá, Corrientes (A. Bodrati, N. Fariña and K. Cockle in litt. 2021). However, the species's apparently scarcity may result at least partially from it being a cryptic, nocturnal species that is often difficult to study. Surveys from 1999-2006 in the coastal plain of Rio Grande do Sul estimated a population of 12 breeding pairs at Capao Novo (218 ha), and 20 breeding pairs at Banhado dos Pachecos (2,544 ha; Accordi 2008).

Based on the minimum and first quartile densities estimates of other nightjar species (0.3 and 0.9 individuals/km2, respectively), the area of the mapped extant range, and assuming 3-10% occupancy, the population size may be calculated to fall within the range 5,000 - 52,000 individuals. However, given the small number of records, the true population size is suspected to be smaller than this (K. Cockle in litt. 2020), so it is here placed in the band 2,500 - 52,000 individuals.

The subpopulation structure is not known, but based on the disjunct range, there are assumed to be at least three subpopulations.

Trend justification: The species's range appears to have contracted considerably over recent decades, so the species's population size is inferred to be declining. It is suspected that the species has lost around half of its range in Argentina over 25 years since the 1990s (A. Bodrati, N. Fariña and K. Cockle in litt. 2021). It is almost certainly extirpated from Buenos Aires, and almost all habitat in Entre Rios has been destroyed (A. Bodrati, N. Fariña and K. Cockle in litt. 2021). The species was recorded in Santiago del Estero (M. Rumboll in litt. 1986), El Palmar National Park, Entre Rios, in 1985 (M. Nares and D. Yzurieta in litt. 1986), and Colon, Entre Rios in 1979 (M. Nares and D. Yzurieta in litt. 1986). In the 1990s, four records were made at three sites in Sao Paulo State, Brazil (Kirwan et al. 1999). In the absence of recent records, the species is now presumed to be locally extinct in all of these regions. The species was known to occur at Puerta Boca, Entre Rios, until around 2000, but the wetland habitat there has since been destroyed (A. Bodrati, N. Fariña and K. Cockle in litt. 2021).

Based on the reduction of the area of the mapped extant range, the species is estimated to have lost approximately 60% of its range since the 1980s. Assuming a constant rate of habitat loss, the species is suspected to have undergone a reduction of 10-19% over the past decade. Assuming that the same area of range continues to be lost per year, up to 46% of the species's remaining range may be lost over the next ten years, so an equivalent population reduction is suspected.


Country/territory distribution
Country/Territory Presence Origin Resident Breeding visitor Non-breeding visitor Passage migrant
Argentina extant native yes
Brazil extant native yes
Paraguay extant native yes

Important Bird and Biodiversity Areas (IBA)
Country/Territory IBA Name
Argentina Bañado La Estrella Este
Argentina Barra Concepción
Argentina Concepción-Chavarría
Argentina Estancia Puerto Valle
Argentina Estancia San Juan Poriahú
Argentina Estero Tapenagá
Argentina Estero Valenzuela
Argentina Fortín Sargento Primero Leyes
Argentina Nacientes de los riachos Monte Lindo y Tatú Piré
Argentina Parque Nacional El Palmar
Argentina Parque Nacional Mburucuyá
Argentina Parque Nacional Pre-Delta
Argentina Parque Nacional Río Pilcomayo
Argentina Reserva de Uso Múltiple Bañados del Río Dulce y Laguna Mar Chiquita
Argentina Reserva Natural Rincón de Santa María
Argentina Riacho He He
Argentina Valle del río Paraguay-Paraná
Argentina Valle Fluvial del Río Paraguay
Argentina Yuto y Vinalito
Brazil Banhado dos Pachecos
Brazil Jaguariaíva
Paraguay Parque Nacional San Rafael
Paraguay Tapyta

Habitats & altitude
Habitat (level 1) Habitat (level 2) Importance Occurrence
Forest Subtropical/Tropical Moist Lowland suitable resident
Grassland Subtropical/Tropical Seasonally Wet/Flooded major resident
Savanna Dry suitable resident
Savanna Moist suitable resident
Wetlands (inland) Bogs, Marshes, Swamps, Fens, Peatlands suitable resident
Wetlands (inland) Permanent Rivers/Streams/Creeks (includes waterfalls) suitable resident
Altitude 0 - 1100 m Occasional altitudinal limits  

Threats & impact
Threat (level 1) Threat (level 2) Impact and Stresses
Agriculture & aquaculture Annual & perennial non-timber crops - Agro-industry farming Timing Scope Severity Impact
Ongoing Majority (50-90%) Rapid Declines Medium Impact: 7
Stresses
Ecosystem degradation, Ecosystem conversion
Agriculture & aquaculture Livestock farming & ranching - Agro-industry grazing, ranching or farming Timing Scope Severity Impact
Ongoing Majority (50-90%) Slow, Significant Declines Medium Impact: 6
Stresses
Ecosystem degradation, Ecosystem conversion
Agriculture & aquaculture Wood & pulp plantations - Agro-industry plantations Timing Scope Severity Impact
Ongoing Minority (<50%) Slow, Significant Declines Low Impact: 5
Stresses
Ecosystem degradation, Ecosystem conversion
Natural system modifications Fire & fire suppression - Increase in fire frequency/intensity Timing Scope Severity Impact
Ongoing Minority (<50%) Slow, Significant Declines Low Impact: 5
Stresses
Ecosystem degradation
Pollution Agricultural & forestry effluents - Herbicides and pesticides Timing Scope Severity Impact
Ongoing Majority (50-90%) Unknown Unknown
Stresses
Ecosystem degradation
Residential & commercial development Housing & urban areas Timing Scope Severity Impact
Ongoing Minority (<50%) Rapid Declines Medium Impact: 6
Stresses
Ecosystem degradation, Ecosystem conversion

Recommended citation
BirdLife International (2024) Species factsheet: Sickle-winged Nightjar Eleothreptus anomalus. Downloaded from https://datazone.birdlife.org/species/factsheet/sickle-winged-nightjar-eleothreptus-anomalus on 22/11/2024.
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 22/11/2024.