Common Diuca-Finch is a common and distinctive species of tanager found from Patagonia north to southern Bolivia. Common Diuca-Finch has a complex taxonomic history due to morphological convergence with finch-like birds and other tanagers that have evolved similar finch-like morphologies. Common Diuca-Finch is principally gray above, becoming blackish over the wings and tail, with a white throat, contrasting somewhat with the otherwise grayish underparts. It is a generally common constituent of the avifauna in shrublands and cultivated areas, and Patagonian deserts, and perches boldly atop low bushes (Jaramillo 2011).
Common Diuca-Finch is a distinctive and common bird within its range in southern South America. Common Diuca-Finch is not likely to be confused in the field because the two species that most closely resemble it, White-winged Diuca-Finch (Idiopsar speculifer) and White-throated Sierra-Finch (Phrygilus erythronotus), are found in the high Andes, while Diuca diuca only occurs in lowlands (Ridgely and Tudor 1989). Common Diuca-Finch has white markings on the tail, which all species of Phrygilus lack. Common Diuca-Finch walks on the ground, similar to the walk of a quail (Jaramillo 2003, Cueto et al. 2013), while White-winged Diuca-Finch hops (Jaramillo 2011). The white eye-crescents of White-winged Diuca-Finch are larger and more pronounced than those of Common Diuca-Finch. Recent phylogenetic analysis has revealed Yellow Cardinal (Gubernatrix cristata) as Common Diuca-Finch’s closest relative (Burns et al. 2014). These two species have hybridized in the wild; hybrids have a morphology is similar to that of the cardinal, while the coloration is more like that of the diuca-finch, except for the presence of the black bib that is characteristic of the cardinal. These hybrids are reported from Argentina in the provinces of southern Buenos Aires, La Pampa, and Río Negro (Bertonatti and Guerra 1997).
Common Diuca-Finch is a medium-sized finch with a plump body; the crown often has a peaked appearance. The following description is based primarily on Jaramillo (2011); see also Geographic Variation:
Adult male: The head is dark gray, darkest around the lores, with a narrow white crescent below the eye. Upperparts generally dark gray, with an olive wash on the back; the lower back and rump blue gray. The rectrices are brownish gray; the inner webs of the three outer rectrices had broad white tips, which are more conspicuous in flight or during frequent but brief spreading of the tail (Sick 1993). The remiges are darker gray, almost blackish, with gray edging. The throat is white, but the breast and flanks are dark gray; the flanks often have a buffy tinge, and become rusty posterior to the tarsi. Belly and vent white. Undertail coverts whitish, with a rusty wash.
Adult female: Similar to the male, but gray of the plumage generally tinged with olive or brownish, and the rusty color on the flanks is paler and less extensive. The sexes are likely more dichromatic than we can perceive in the UV spectrum, as evidenced when color is measured under a model of avian vision (Burns and Shultz 2012).
Juvenile: Similar to adult female in coloration, but the vent is buff rather than rufous.
Tanagers that have been studied have either a Complex Basic Strategy or Complex Alternative Strategy (Ryder and Wolfe 2009). However, most tanagers only molt once a year (Isler and Isler 1987), and this prebasic molt most likely occurs after the breeding season (Isler and Isler 1987, Ryder and Wolfe 2009). Many species have been found to breed in subadult plumage (Isler and Isler 1987). Although a juvenile plumage is described for Diuca diuca (Jaramillo 2011), more specific information on molt and its timing is not available for this species.
Bill: stout, with a rounded culmen. maxilla black; mandible blue gray
Tarsi and toes: brownish gray to blackish
Bare parts data from Sick (1993), Jaramillo (2003), and Jaramillo (2011).
Both sexes are about 16-18 cm in length, most commonly reported as 16-17 cm (Ridgely and Tudor 1989, Sick 1993, Jaramillo 2003, Perlo 2009, Ridgely and Tudor 2009). Both sexes have a mass of about 37 g, with more specific and further measurements in Table 1 below (Egli 1996, Marin 2011). Detailed measurements of nestling growth can also be found in Marin (2011).
Table 1. Standard Measurements
|Reference:||Egli 1996||Marin 2011|
|Weight (g)||36.8||31-41||21||33.7||11 |
|Total length (mm)||167.4||154-181||23||-|| -|
|Wing (mm)||86.5||80-92||23||89.8||26 |