Proposal
(256) to South American Classification Committee
Move Caprimulgus
candicans from Caprimulgus to Eleothreptus
Effect on SACC: Move White-winged Nightjar Caprimulgus
candicans from Caprimulgus to Eleothreptus.
Background:
The genus Eleothreptus
G. R. Gray, 1840
Morphological characteristics that separate this genus from Caprimulgus are
a broader bill, proportionally longer rictal bristles, a short, square tail and
partially feathered tarsi. Males also have strongly curved primaries, but the
short secondaries of male Sickle-winged Nightjars may have evolved through
territorial and courtship display activity and possibly do not constitute a
generic character.
Sickle-winged
Nightjar Eleothreptus anomalus (Gould, 1838)
Description: A small, sexually dimorphic nightjar, approximately
18 - 20 cm in length and relatively short tailed. Males are generally greyish-brown,
often tinged cinnamon, and occasionally show an indistinct buffish collar on
the hindneck. They have a pale buffish-white stripe above the eye and an
indistinct, greyish-white submoustachial stripe, but lack a white patch on the
throat. The primary coverts are cinnamon, which show as a diagnostic pale patch
on the closed wing, and the scapulars have distinctive blackish markings,
shaped like inverted Christmas trees. The primaries are strongly curved,
largely blackish, and the outer six are boldly tipped whitish. The secondaries
are extremely short and together with the curved primaries, they form the
unique wing shape. The tail is broadly barred cinnamon-buff and the outer three
feathers are narrowly tipped whitish or buffish-white. Females are browner,
often with longer wings and tails, and lack the distinctive wing shape. The
primaries and secondaries are brown, barred tawny and very narrowly tipped
buffish-white. Immatures are similar to the adults, although males lack the
characteristic wing shape of adult males; juveniles are similar to the adult
females (Cleere 1998, 1999).
Range: Central and eastern Brazil, eastern Paraguay and north-eastern
Argentina. Probably resident throughout most of its range, although may be a
migrant only (September to March?) in the south. Occurs in open country from
Distrito Federal and Minas Gerais in Brazil, south and south-west through
southern Brazil and eastern Paraguay to Córdoba and Buenos Aires in
north-eastern Argentina.
Habitat: Inhabits seasonally flooded grasslands (Miatello et al. 1991,
Straneck & Viñas 1994), savanna and grassland with marshes, streams and
areas of surface water (Cleere 1998), grassland close to dry degraded woodland
and water (Kirwan et al. 1999) and gallery forest, chaco-type
woodland and transitional woodland, often near water or marshland (Collar et
al. 1992, Pearman & Abadie 1995).
Vocalizations and behaviour: Crepuscular and nocturnal. Calls
include rapid chip, tchup or tchut notes,
which may be rather weak. Females also utter harsh gzee, gzee sounds
(Straneck & Viñas 1994, Cleere 1998). In the breeding season, males perform
short display flights during which they make muffled wing flapping sounds
(Straneck & Viñas 1994). Roosts and nests on small patches of bare earth
amongst clumps of vegetation. Often sits on roads, tracks and low perches at
night. When foraging, the fluttery flight is interspersed with glides and
sudden changes of direction. Also hunts from the ground by making short sallies
(Straneck & Viñas 1994, Pearman & Abadie 1995, Cleere 1998).
Eggs: Very few eggs of this species appear to have been found,
collected, or described in the literature. Two were taken on 17 November in São
Paulo, Brazil (Ihering 1902); two on 28 November 1925 in Rio Grande do Sul,
Brazil (Lowen 1999) and one in mid-November in Santiago del Estero, Argentina
(Pereyra 1950). There is also an egg deposited in the Western Foundation for
Vertebrate Zoology (catalogue no. 154.874), collected on 7 October 1936 in
Minas Gerais, Brazil. The eggs are elliptical, 23.2 - 31. 4 x 18.2 - 22.8 mm,
have a buffish or pinkish-buff ground colour, and are finely spotted and
scrawled brown and grey.
White-winged
Nightjar Caprimulgus candicans (Pelzeln, 1866)
Description: A small, sexually dimorphic nightjar, approximately
19 - 21 cm in length. Males are generally greyish-brown, often tinged cinnamon,
and have no collar on the hindneck. They have a whitish stripe above the eye
and a whitish submoustachial stripe, but lack a white patch on the throat. Some
outer lesser coverts, the alula and the primary coverts are mostly white,
although this is not generally visible on the closed wing. The scapulars have
strong blackish markings, which are occasionally shaped like inverted Christmas
trees. The primaries are curved and are largely white proximally, blackish
distally, the amount of white increasing on each feather towards the body. The
secondaries are also mostly white, as is the tail, with only the central pair
of tail feathers being pale greyish-brown. Females are browner, completely lack
white in the plumage, and the primaries and secondaries are brown, regularly
barred pale tawny. Immatures and juveniles are similar to adult females (Cleere
1998, 1999).
Range: Central and south-western Brazil, eastern Paraguay and northern
Bolivia. Probably resident throughout it's range. Occurs in open, lowland
country in Goiás, Brazil and Canindeyú, Paraguay. There are historical records
from Mato Grosso and São Paulo, Brazil. The modern record from Beni, Bolivia
(Davis & Flores 1994) remains an isolated one to-date.
Habitat: Inhabits open grasslands and cerrado with scattered trees,
bushes, dwarf palms, termite mounds and anthills (Pelzeln 1868, Collar et
al. 1992, Clay et al. 1997, Lowen et al. 1997).
Possibly favours areas that are regenerating after fires (Collar et al. 1992,
Rodrigues et al. 1999), although further research is
recommended (Capper et al. 2000).
Vocalization and behaviour: Crepuscular and nocturnal. Males
give undulating whistles during territorial disputes or when alarmed. Females
utter sharp, single notes (Cleere 1998).
In the breeding season, males perform short display flights from
low termite mounds, during which they make rapid, wing fluttering sounds
(Clay et al. 2000), the white wing and tail feathers being
extremely noticeable. Roosts and nests on small patches of bare soil in cerrado
or grassland, usually beneath overhanging grasses and plants. Appears to rely
on crypsis less than other nightjar species, using nearby vegetation for
protection during the day. Does not appear to sit on roads and tracks at night,
but frequently uses low perches. When foraging, flight is often slow and
interspersed with frequent glides. At other times, flight is strong and direct
with a series of double wing beats and short glides.
Eggs: The first eggs of this species were discovered in Canindeyú,
Paraguay on 22 November 1997 (Capper et al, 2000). As a result of
intensive field studies, several nests have been found in the same region
during the years 1998, 1999 and 2000 (Pople pers. comm.). The eggs are
elliptical, 28.7 - 28.9 x 21.3 - 21.4 mm, have a buffish or creamy-brown ground
colour and are finely spotted and scrawled grey, black and brown.
Analysis
The Sickle-winged and White-winged Nightjars are two poorly known,
Neotropical species that share similar morphological features, vocalizations,
behavioural traits and habitat preferences. Both have restricted ranges,
occurring in open grasslands in southern South America, generally where there
are reddish soils. They are both sexually dimorphic. Males have
cinnamon-tinged, cryptic plumages and lack the white mid-wing and outer tail
markings typically found in the genus Caprimulgus. Females have a
brownish, variegated plumage, although they do not appear to nest or roost on
leaf litter. Males have curved primaries that, during territorial and courtship
display flights, produce a flapping sound quite unlike the deliberate clapping
given by many Caprimulgus nightjars, which have straighter primaries.
The wings of the males have also evolved to different extremes. The
Sickle-winged Nightjar has the strangest shaped wing of all nightjar species,
and appears to have a sound-orientated display flight. The White-winged Nightjar
has more white in the wing than any other species, and appears to have a more
visual display. In between display flights, the males of both species give
similar, soft, call notes, although descriptions of these vocalisations have
yet to be published. The eggs of both species are rather similar, having a
buffish ground colour with fine markings, and differ from those of most Caprimulgus eggs,
which generally have a whitish ground colour and are boldly spotted and
blotched. Both species also share the broader bill, proportionally longer
rictal bristles and partially feathered tarsi, which further differentiate them
from Caprimulgus nightjars.
Recommendation:
The White-winged Nightjar is clearly not a Caprimulgus
species and is probably a close relative of the Sickle-winged Nightjar. I
propose that this species be moved into the genus Eleothreptus with the
name White-winged Nightjar Eleothreptus candicans. This proposal is a
shortened version of the paper by Cleere 2002.
References cited:
Capper, D.R., Esquivel, E.Z., Pople, R.G., Burfield, I.J., Clay,
R.P., Kennedy, C.P. & Mazar Barnett, J. 2000. Surveys and recommendations
for the management of Aguará Ñu in the Reserva Natural del Bosque Mbaracayú,
eastern Paraguay. Unpublished report.
Clay, R.P., Capper, D.R., Mazar Barnett, J., Burfield, I.J.,
Esquivel, E.Z., Fariña, R., Kennedy, C.P., Perrens, M. & Pople, R.G. 1997.
White-winged Nightjars Caprimulgus candicans and cerrado
conservation: the key findings of Project Aguará Ñu 1997. Cotinga 9:
52 - 55.
Clay, R.P., López Lanús, B., Tobias, J.A., Lowen, J.C. & Mazar
Barnett, J. 2000. The display of the White-winged Nightjar. J. Field
Orn. 71: 619 - 626.
Cleere, N. 1998. Nightjars. A guide to nightjars and
related nightbirds. Pica Press, Sussex.
Cleere, N. 1999. Family Caprimulgidae (Nightjars). In:
del Hoyo J., Elliott A. & Sargatal J. (eds) Handbook of the birds
of the world Vol. 5.: 302 - 386. Lynx Edicions, Barcelona.
Cleere, N. 2002. A review of the taxonomy and systematics of the
Sickle-winged and White-winged nightjars (Caprimulgidae). Bull. Brit.
Orn. Cl. 122 (3): 168 - 179.
Collar, N.J., Gonzaga, L.P., Krabbe, N., Madroño Nieto, A.,
Naranjo, L.G., Parker, T.A. & Wege, D.C. 1992. Threatened birds of the
Americas. The I.C.P.B./I.U.C.N. Red Data Book, Cambridge, U.K.
Davis, S.E. & Flores, E. 1994. First record of White-winged
Nightjar Caprimulgus candicans for Bolivia. Bull. Brit. Orn. Cl. 114:
127 - 128.
Gould, J. 1838. A very singular form among the
Caprimulgidae. Proc. Zool. Soc. London 1837: 105.
Gray, G.R. 1840. A List of the genera of birds with an
indication of the typical species of each genus. R. & J. E. Taylor,
London.
Ihering, H. 1902. Contribuições
para o conhecimento da ornitologia de São Paulo. Rev. Mus. Paulista 5:
261 - 329.
Kirwan, G.M., Martuscelli, P., Silveira,
L.F. & Williams, R.S.R. 1999. Recent records of the Sickle-winged
Nightjar Eleothreptus anomalus in south-east Brazil. Bull.
Brit. Orn. Cl. 119: 202 - 206.
Lowen, J.C. 1999. Um novo
registro da reprodução de Eleothreptus anomalus (Caprimulgiformes:
Caprimulgidae) para o Brasil. Ararajuba 7: 139.
Lowen, J.C., Clay, R.P., Barnett, J. M., Madroño, N. A., Pearman,
M., Lanús, B. L., Tobias, J. A., Liley, D. C.,
Brooks, T. M., Esquivel, E. Z. & Reid, J. M. 1997. New and noteworthy
observations on the Paraguayan avifauna. Bull. Brit. Orn. Cl. 117:
275 - 293.
Miatello, R, Cobos, V. & Rosacher, C. 1991. Algunas
especies de aves nuevas o poco conocidas para la provincia de Córdoba,
República Argentina. Hist. Nat. 8: 1 - 5.
Pearman, M. & Abadie, E. 1995. Field identification, ecology
and status of the Sickle-winged Nightjar Eleothreptus anomalus. Cotinga 3:
12 - 14.
Pelzeln, A. 1868. Zur Ornithologie Brasiliens Pt.
1. A. Pichler's Witwe und Sohn, Wien.
Pereyra, J.A. 1950. Avifauna Argentina. Hornero 9:
178 - 241.
Rodrigues, F.H.G., Hass, A., Marini-Filho, O.J., Guimarães, M.M. & Bagno, M.A.
1999. A new record of White-winged Nightjar Caprimulgus candicans in
Emas National Park, Goiás, Brazil. Cotinga 11:
83 - 85.
Straneck, R.J. & Viñas, M.J. 1994. Comentarios sobre costumbres y manifestaciones acusticas
del atajacaminos de los pantanos, Eleothreptus
anomalus (Gould 1838) (Aves, Caprimulgidae). Notulas Faunisticas
67: 1 - 4.
Nigel
Cleere, January 2007
Additional note from Remsen: Barrowclough et al. (2006) [see
our SACC bibliography -- I have pdf I you need one] found that Caprimulgus
is highly polyphyletic, with none of the New World species related to true Caprimulgus
of Old World, and New World "Caprimulgus" themselves not a
monophyletic group; unfortunately, they didn't have samples of candicans
or anomalus.
_______________________________________________________________________________________________
Comments from Stiles: "A tentative NO, for now.
Cleere is quite likely right, but given the obviously unsettled state of
generic-level taxonomy of the New World Caprimulgus following
the Barrowclough et al. study, I would prefer to await more information
including a genetic study with more comprehensive taxon sampling. Given the
lack of genetic data on these two species and the strong sexual selection
likely behind their distinctive characters, there exists the possibility that
they may be best included with other species in a different genus, or turn
out not to be sister species.... hence better to wait on this one."
Comments from Zimmer: "YES". Gary's point
about waiting for a molecular-based refinement of New World Caprimulgus is
well taken, and part of me is tempted to vote NO for that reason. I do think
that a molecular-based phylogeny will result in more (potentially drastic)
shuffling in this group. That said, I don't think it hurts to move in a
particular direction based on evidence available at the time, even if it means
revisiting the issue later. As Nigel Cleere points out, there a number of
characters that would seem to unite candicans and anomalus, and
until we see molecular evidence to the contrary, I'm willing to go in this direction."
Comments from Nores: "NO. Aunque el análisis de Cleere me parece muy bueno y los aspectos
marcados me parecen bastante convincentes, no estoy convencido de que sean
congenéricos. La aclaración que hace Cleere en el primer párrafo de que el diseño
de las plumas del ala puede haber evolucionado de un display territorial y
cortejeo y que posiblemente no constituye un carácter genérico tiene para mi
poca base, y por medio de ese análisis elimina uno de los caracteres más
importantes del género. Pienso que este es un caso que necesita especialmente
un análisis genético."
Comments from Cadena: "YES. The reasoning
presented by Cleere is convincing, and although taxon sampling across the
family is not great, a recent study based on cytochrome b sequence data (Larsen
et al. 2007 Molecular Phylogenetics and Evolution 42: 789-796) placed anomalus
and candicans as sister taxa, forming a strongly supported clade that
excludes Caprimulgus longirostris, C. maculicaudus, C.
vociferus, C. inornatus, C. europaeus, C. climacurus,
and C. fraenatus. Importantly, europaeus is the type
species of Caprimulgus. Considering the rampant polyphyly of Caprimulgus shown
by recent studies (including a recent master’s thesis by Kim Han that hasn't
been published but has good taxon sampling, fide Mike Braun), this seems like a
logical first step in the right direction."
Comments from Robbins: "NO, although it is likely
that candicans is sister to anomalus, a robust, unpublished
molecular data set (Kin-Lan Han et al.) demonstrates that the genus Eleothreptus,
as well as a few other genera, will need to be subsumed into another genus that
has priority. Kin, Mike Braun, and I plan to soon submit these results for
publication. Thus, there is no point in making this change when both of these
taxa will have to be transferred to another genus."
Comments from Jaramillo: "YES - The Cleere analysis I
buy, and the other non-sexually selected features he notes (feathered tarsi
etc.) are good indicators that he is probably right in suggesting a sister
relationship between these two taxa. My huge hesitation is due to the comment
by Robbins, but on the other hand, we can only act on data that is out there
already. I see no reason to accept this more favorable (than keeping candicans
in Caprimulgus) arrangement for now, and re-assess when new data is
published. It can take so long for data to finally get out there, that I would
rather act on something now, than wait. Call me impatient."
Comments from Remsen: NO. The sister relationship looks
solid, but if the two Eleothreptus make one of the newly constituted New
World genera (ex-Caprimulgus) paraphyletic, then we will have to reverse
the decision."