Blue-and-gold Tanager (Bangsia arcaei) is among the rarer species of birds in Central America. There are two described subspecies, nominate B. a. arcaei, and B. a. caeruleigularis. This species is similar in appearance to Blue-and-yellow Tanager (Pipraeidea bonariensis), and characteristics to distinguish these birds are outlined below under Similar Species. Little is known about B. arcaei, and further research is in order.
Blue-and-gold Tanager (Bangsia arcaei), with its dark blue black back, rump, hood, wings, and sides, combined with the yellow-gold colored belly and breast, is not likely to be confused with any species within its range. Optimistic observers unfamiliar with euphonias may mistake the two, particularly for birds that are poorly seen. Euphonias are much smaller, however, with small bills, and most species have either yellow on the crown or throat.
The following description refers to the nominate subspecies B. a. arcaei; for B. a. caeruleigularis see Geographic Variation:
Adult: The crown is bright blue relative to the rest of the body. It has a strong black bill that is heavy for its size (Hilty 2011). The wings and tail are a dark blue color, almost black. The dark feathers of the wing are edged dark blue. The sides have a dusky mottling, which blotches into bright golden-yellow flanks, thighs, belly, crissum, and breast (Ridgely and Gwynne 1989). The sexes appear similar to the human eye. However, plumage dichromatism is present when analyzed using a model based on the avian visual system (Burns and Shultz 2012).
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, 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). More specific information on molt and its timing is not available for this species.
The irises are red (Ridgely and Gwynne 1989), the mandible is black, and the tarsi, feet, and toes are blackish (Hilty 2011).
Total length: 13.3 cm (Wetmore et al. 1984), 15.0 cm (Hilty 2011)
males (n = 2, Wetmore et al. 1984):
wing length: range 83.8-87.5 mm (mean 85.5 mm)
tail length: range 46.6-48.6 mm (mean 47.6 mm)
bill length (culmen from base): range 17.4-19.2 nn (mean 18.3 mm)
tarsus length: range 21.6-22.6 mm (range 21.7 mm)
female (n = 4, Wetmore et al. 1984):
wing length: range 84.0-86.5 (mean 85.5 mm)
tail length: range 43.1-45.8 (mean 44.1 mm)
bill length (culmen from base): range 16.0-18.2 (mean 16.9 mm)
tarsus length: range 20.4-22.8 (mean 21.7 mm)
Mass: 34.6 g and 39.9 g (n = 2, Dunning 2008)