Curve-billed Scythebill (Campylorhamphus procurvoides) [XC808588]
by id from Cana\u00e3 dos Caraj\u00e1s, Par\u00e1, Brazil (song)
Curve-billed Scythebill (Campylorhamphus procurvoides) [XC371374]
by Caio Brito from Caraj\u00e1s National Park - Parauapebas - Par\u00e1 - Bras\u00edl, Brazil (call, song)
Subspecies
Suggested as sister-species of Red-billed Scythebill (Campylorhamphus trochilirostris), with relationships among some taxa in group unclear. Subspecies form two groups, differing both vocally and morphologically: northern "procurvoides group" (including poorly differentiated sanus) and southern "multostriatus group" (with probatus and similar successor). Birds from south-eastern Amazonia (multostriatus) are morphologically intermediate between Red-billed Scythebill (Campylorhamphus trochilirostris) and nominate of Curve-billed Scythebill (Campylorhamphus procurvoides), and members of entire "multostriatus group" are vocally more similar to Red-billed Scythebill (Campylorhamphus trochilirostris). Assessment of geographic variation complicated by marked individual variation in overall coloration, and extent and width of streaking on both back and underparts. Specimens from islands in lower Amazon R (near Obidos, Brazil) have been attributed to successor, but this is unlikely on grounds of both ecology and biogeography.
The following 7 subspecies are recognised:
sanus Zimmer, JT, 1934 - North-western Amazonia, from south-eastern Colombia (western Meta, western Caquetá), north-eastern Ecuador (Sucumbios) and extreme north-eastern Peru east to extreme north-western Brazil (upper R Negro), southern and eastern Venezuela (southern Amazonas, north-eastern Bolívar; sight record from Monagas) and northern Guyana.
procurvoides (Lafresnaye, 1850) - North-eastern Amazonia, in Surinam, French Guiana and Brazil north of Amazon (lower R Negro east to Amapá).
successor Todd, 1948 - South-western Amazonia, south of Amazon in western Brazil from northern Acre east to R Madeira. Also reported from river islands in lower Amazon R in Pará (near Obidos).
probatus Zimmer, JT, 1934 - South-central Amazonian Brazil, south of Amazon, between R Madeira and R Tapajós, south to central Rondônia and north-western Mato Grosso. Considered by some authors to be a distinct species, Tapajos Scythebill (Campylorhamphus probatus).
multostriatus (Snethlage, E, 1907) - South-eastern Amazonian Brazil, south of Amazon, from R Tapajós east to R Tocantins, south to north-eastern Mato Grosso. Considered by some authors to be a distinct species, Xingu Scythebill (Campylorhamphus multostriatus).
gyldenstolpei Aleixo et al., 2013 - Southwest Amazonian Brazil, west of the Madeira River; possibly also in eastern Peru (south of the Amazon).
cardosoi Portes et al., 2013 - Eastern Amazonian Brazil, between the Tapajós and Xingu rivers.
BirdLife International Species Factsheet