- Order: Passeriformes
- Family: Emberizidae
- Polytypic 3 Subspecies
Arremon sparrows are small to medium sized finches with extensive black on the head, contrasting with a white throat. Pectoral Sparrow is a small Arremon. The upperparts are green, becoming more yellowish at the bend of the wing. Apart from the white throat, the head is mostly black, with a contrasting white supercilium and a gray median crown stripe. The underparts primarily are white (male) or creamy (female); the male also has a broad black band at the side of the breast, which in some subspecies extends all the way across the breast. The bill is black or (in one subspecies) black above, with a pale mandible.
The distributions of Arremon sparrows are largely allopatric or parapatric; consequently, Pectoral Sparrow usually is the only small forest sparrow with a black and white striped head pattern within its range. In northern Colombia and northwestern Venezuela, the distribution of Pectoral Sparrow approaches (but apparently does not contact) that of Golden-winged Sparrow (Arremon schlegeli), which occupies drier forest, lacks the white supercilium and crown stripe, has a bright yellow bill, and has a broad area of bright yellow on the upper surface of the wing. The distributions of Pectoral and Orange-billed (Arremon aurantiirostris) sparrows may approach each other in eastern Colombia, although these two species also are not known to be in contact; Orange-billed Sparrow is distinguished by its namesake bill color. The distribution of the nominate subspecies of Pectoral Sparrow also is parapatric with that of Half-collared Sparrow (Arremon semitorquatus) in southeastern Brazil. Among other differences between these two species, Half-collared Sparrow has an incomplete black breast band (complete in nominate taciturnus), and a yellow mandible (bill entirely black in nominate taciturnus).
The song of Pectoral Sparrow is high and thin. It has been described as "insect-like .. an extremely high, thin, buzzy chit-tic-tzzzzzz, tzzzzzz, tzzzzz" (axillaris, Venezuela; Hilty 2003) and "sim[ilar] or varied to tzzz, tzzz, tzzz, zzzzzzzzzzzzit" (nominate taciturnus, Venezuela; (Hilty 2003); and as "a high, lisping tik-tseeeeeeu tseeeeeu" (nigrirostris, Peru; Lane, in Schulenberg et al. 2007).
The call is described as a "sharp tzip ... like others of genus" (Hilty 2003) or as "a high tik" (Lane, in Schulenberg et al. 2007).
Detailed Description (appearance)
The following description refers to nominate taciturnus, and is based on Restall et al. (2006) and on Jaramillo (2011); see also Geographic Variation.
Adult male: Sides of head and crown black, with gray median crown stripe and nape, and a well defined white supercilium, extending from in front of eye (but not to lores) to nape. Upperparts generally yellowish olive, yellower on the wing coverts; carpal area golden yellow. Throat white; border with black of sides of head sharply defined. Underparts white, with broad black band across breast; flanks washed with light gray, undertail coverts buffy.
Adult female: Pattern similar to that of male, but plumage generally duller, with darker olive upperparts and the yellow of the wing is less extensive and less bright. Underparts off white to creamy or buffy. The pectoral band is reduced, and is grayish or dusky, not black.
Juvenile: Less patterned. Generally dark olive above and buffy yellow below, with darker breast and flanks. Crown dark olive; sides of head dusky, with some white on the supercilium. Lacks yellow on the wing.
Iris: brown (Willard et al. 1991)
Bill: black (Willard et al. 1991) or (axillaris) maxilla black, mandible yellow (Hellmayr 1938, Hilty and Brown 1986, Jaramillo 2011)
Tarsi and toes: pinkish gray (Willard et al. 1991)
Total length: 15 cm (Hilty and Brown 1986, Ridgely and Tudor 1989, Hilty 2003, Jaramillo 2011)
Linear measurements, nigrirostris (Hellmayr 1938):
wing length, male: 76-80 mm; wing length, female: 74-75 mm
tail length, male: 64-67 mm; tail length, female: 58-60 mm
bill length (sexes combined?), 14-15 mm
Mass: taciturnus, Venezuela (Willard et al. 1991):
male, mean 24.6 g ± 1.32; range 22.7-26.8, n = 15
female, mean 24.3 g ±1.26; range 22.0-25.9, n = 8
Little information. At one site in southern Venezuela, body molt noted on three specimens from mid-February to mid-March, but no molt noted on a specimen from early December (Willard et al. 1991).
Three subspecies currently recognized:
axillaris Sclater 1855; type locality "in Nova Grenada"; holotype in the (British) Natural History Museum
Occurs in eastern Colombia and northwestern Venezuela. Differs from nominate taciturnus by the yellow mandible; black breast markings reduced to a band on either side of the breast, not complete across the center of the breast; yellow of wing coverts more extensive, and including yellow edgings to greater coverts (Hellmayr 1938, Jaramillo 2011)
taciturnus (Hermann 1783); type locality Cayenne
Occupies the bulk of the range of the species, from southeastern Colombia east to southern Venezuela and the Guianas, south through Amazonia to central Brazil and northeastern Bolivia, and along the Atlantic coast of Brazil south to Espírito Santo.
See Detailed Description.
nigrirostris Sclater 1886; type locality Cosnipata, Cuzco, Peru; holotype in the (British) Natural History Museum
Occurs in southeastern Peru and northwestern Bolivia (La Paz, Cochabamba), and presumably in adjacent southwestern Brazil
Bill black, as in nominate taciturnus. Differs from taciturnus by black breast markings reduced to a band on either side of the breast, not complete across the center of the breast; the female completely lacks the pectoral patches (Hellmayr 1938, Jaramillo 2011)
A fourth taxon, semitorquatus of southeastern Brazil, long was classified as a subspecies of taciturnus (e.g. Hellmayr 1938, Paynter 1970). This classification was based in part on a few specimens from Rio de Janeiro and São Paulo that were interpreted as intermediate between semitorquatus and taciturnus (Hellmayr 1938). Raposo and Parini (1997) documented that the distribution of semitorquatus extends farther north than previously was known; that the zone of potential introgression reported by Hellmayr (1938) in fact is within the range of semitorquatus (and distant from the nearest localities of taciturnus); that the taxa are nowhere sympatric; and that there are no specimens that show signs of introgression between semitorquatus and taciturnus. As a result, semitorquatus now is classified as a separate species, Half-collared Sparrow.
There is no complete phylogeny for the genus Arremon. Traditionally Arremon consisted of five-seven species of similarly sized "sparrows", but phylogenetic analyis of DNA sequence data (from both mitochondrial and nuclear genes) reveals that the Arremon sparrows are embedded within a larger clade that also includes two larger species (Sooty-faced Finch Arremon crassirostris and Olive Finch Arremon castaneiceps) that previously were classified in the genus Lysurus; and also includes larger bodied taxa of brush-finch formerly classified in the genus Buarremon (Chestnut-capped Brush-Finch Arremon brunneinucha and members of the Stripe-headed Brush-Finch complex Arremon torquatus senso lato) (Cadena et al. 2007).
Valdez-Juarez, Simon Octavio, Thomas S. Schulenberg, and Alvaro Jaramillo. 2012. Pectoral Sparrow (Arremon taciturnus), Neotropical Birds Online (T. S. Schulenberg, Editor). Ithaca: Cornell Lab of Ornithology; retrieved from Neotropical Birds Online: http://neotropical.birds.cornell.edu/portal/species/overview?p_p_spp=%0A%09%09%09%09646796