Opal-crowned Tanager is a medium sized species of the genus Tangara, primarily colored blue, black, and white. The belly is dark blue and the upper back is black. It has a distinct opalescent forecrown and brow, from which it derives its English name. The rump also is opalescent. The specific epithet, callophrys, comes from two Greek words - "Kallos", which refers to beauty, and "Ophrys", which refers to eyebrow (Jobling 2010). Collectively, the scientific and common name of this species refers to its distinctive crown pattern.
Opal-crowned Tanager is very distinctive; it is easily recognizable due to its conspicuous opal forecrown and brow. The vocalizations of Opal-crowned Tanager are similar to that of Turquoise Tanager (Tangara mexicana); however, Opal-crowned Tanager has a higher pitched "zit" call that can last 1-5 seconds (Isler and Isler 1987). Species similar in appearance to Opal-crowned Tanager include Opal-rumped Tanager (Tangara velia), Turquoise Tanager, and Paradise Tanager (Tangara chilensis). These species have slightly different elevational preferences, with Opal-rumped Tanager strictly confined to the lowlands (200-600 m), while Turquoise Tanager ranges up to 1100 m, and Paradise Tanager up to 1600 m (Naoki 2003). Nonetheless, all of these species often are syntopic in western Amazonia, but are separated by plumage differences (Restall et al. 2007). In addition to its unique opal forecrown and brow, Opal-crowned Tanager has a black center to its belly and undertail coverts (in contrast to the chestnut red belly of Opal-rumped Tanager).
Adult: Bright deep blue auriculars, malar, and throat that extend all the way to the breast, sides, flanks, and belly. The forecrown is a bright opalescent yellow that extends distally as a broad brow over the eye to the sides of the nape. The center of the crown and the nape are a very deep black (Hilty 2011). The scapulars and mantle are black as well. The coverts are generally black, with dark blue on the edges of the primary, median, and primary coverts. The rump is an opalescent to opalescent yellow color, with a tinge of blue on the nearby feathers. The bill is short and thick (standard for the genus Tangara) (Isler and Isler 1987). The sexes appear similar to the human eye. Plumage dichromatism is present, however, when analyzed using a model based on the avian visual system (Burns and Shultz 2012).
There is no information on the molt of Opal-crowned Tanager, and the juvenile and immature plumages are undescribed (Hilty 2011). Little information on molt in tanagers as a whole is available, but generally the juveniles have similar plumages to the definitive adult plumages but are less vibrant (Ryder and Wolfe 2009). Tanagers that have been studied have either a Complex Basic Strategy or Complex Alternative Strategy (Ryder and Wolf 2009). However, most tanagers only molt once a year (Isler and Isler 1987), and this prebasic molt 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). In many species of Tangara, the preformative molt is partial (Ryder and Wolfe 2009). More specific information on molt and its timing is not available for Opal-crowned Tanager.
Iris: dark brown (Restall et al. 2007, Hilty 2011)
Bill: black (Restall et al. 2007, Hilty 2011)
Tarsi and toes: black (Hilty 2011) or horn (Restall et al. 2007)
Total length, both sexes: 14 cm (Isler and Isler 1987), 14.5 cm (Ridgely and Greenfield 2001), 14.7 cm (Hilty and Brown 1986)
Mass, both sexes: mean: 22.9 g (range 21-26.5 g, n = 5, sexes combined; Dunning 2008)