Bay-headed Tanager Tangara gyrola

  • Order: Passeriformes
  • Family: Thraupidae
  • Polytypic: 9 subspecies
  • Authors: Kevin J. Burns and Cyndarienne Mireles
Sections

Systematics

Geographic Variation

Nine subspecies of the Bay-headed Tanager are recognized (Storer 1970, Clements et al. 2009). These nine subspecies sometimes are sorted into three subspecies groups (e.g., Sibley and Monroe 1990, American Ornithologists' Union 1998), as follows:

albertinae group (called the gyroloides group by Sibley and Monroe 1990 and the American Ornithologists' Union 19998) - Includes six subspecies. All have a blue rump and blue underparts.

T. g. bangsi - The yellow of the nuchal collar and of the wing coverts is reduced (Hellmayr 1936). Occurs in Costa Rica and in western Panama, east to Coclé; populations in the Canal Zone and in eastern part of the province of Panamá show characters that are intermediate between bangsi and deliticia (Storer 1970, Wetmore et al. 1984).

T. g. deleticia - The yellow nuchal band and yellow on the wing coverts are absent or almost absent. Occurs in eastern Panama (Darién) and in the western and central Andes of Colombia, east to the west slope of the eastern Andes of Colombia (Storer 1970, Hilty and Brown 1986).


T. g. nupera –Similar to bangsi, from which "differs merely by somewhat paler ... head and slightly lighter, more greenish blue of the under parts" (Hellmayr 1936). Occurs from the western slope of the western Andes of southern Colombia in Nariño, south through western Ecuador to extreme northwestern Peru in Tumbes (Storer 1970, Wiedenfeld et al. 1985, Hilty and Brown 1986, Ridgely and Greenfield 2001).


T.g. catharinae – This subspecies a green throat, but an extensive blue area in the lower breast and belly. It is somewhat similar to nominate gyrola, but "yellow nuchal collar much wider, the head much darker ... [has] a light cerulean blue patch on the rump, and the under parts much more extensively blue" (Hellmayr 1936). Occurs on the east slope of the Andes from southern Colombia (Meta south) south through the Andes of Ecuador and Peru to central Bolivia in Cochabamba and Santa Cruz (Storer 1970).


T. g. parva – This subspecies a green throat, but an extensive blue area in the lower breast and belly. It is much like catharinae, "but wing and tail shorter; adult males with brown of cap averaging darker; yellow of collar and shoulder slightly lighter; blue of rump and under parts and green of back averaging a little lighter" (Zimmer 1943). Occurs from the lowlands of southeastern Colombia and southern Venezuela south to Peru (south at least to Pasco) and east to western Brazil north of the Amazon (Zimmer 1943, Storer 1970).

T. g. albertinae-  Similar to catharinae, but the most distinctive feature is that the wing coverts are rufous rather than yellow or yellowish green. Also the nuchal band is indistinct, and the "hind neck and upper back [are] much more yellowish" (Hellmayr 1936). Occurs in western Brazil south of the Amazon (Storer 1970).

viridissima group - Two subspecies. These two subspecies are almost entirely green, except for the chestnut head; the rump and underparts both are entirely green; and the yellow of the nuchal band and of the wing coverts is reduced or absent.

T. g. toddi – Occurs in northern Colombia in the Santa Marta mountains, on the east slope of the eastern Andes in Norte de Santander and northern Boyacá, in the Andes of Venezuela, and in the coastal cordilleras of Venezuela east to Miranda (Storer 1970, Hilty and Brown 1986, Hilty 2003).

T. g. viridissima – Very similar to toddi, but the rufous of the head is darker, and the underparts are more bluish green (Hellmayr 1936). Occurs on Trinidad; populations in the eastern coastal cordilleras of Venezuela in Anzoátegui, Monagas, and Sucre are intermediate between viridissima and toddi (Storer 1970).

gyrola group - One subspecies, which has a green rump, a green throat, and an extensive blue area on the lower breast and belly.


T. g. gyrola – See Detailed Description. It occurs in southern Venezuela and adjacent northern Brazil east across the Guianas to Amapá, Brazil (Storer et al. 1970, Novaes 1978).

In addition to the above descriptions, the following table (from Nørgaard-Olesen 1973) can be used to separate the subspecies:

Subspecies Wing-coverts Nape-band Rump Belly Throat Bill
gyrola golden narrow-indistinct green blue green  
albertinae chestnut-brown indistinct blue blue   10-11 mm
catharinae golden narrow-distinct blue blue green  
parva golden narrow-distinct blue blue green  
nupera golden distinct blue blue blue 12-13 mm
deleticia missing missing blue blue blue 12-13 mm
bangsi golden indicated blue blue bluish 12-13 mm
viridissima yellow-green narrow green green-blue green-blue  
toddi yellow-green narrow green green green 10.5-12 mm

Related Species

The Bay-headed Tanager is classified in the genus Tangara, the largest genus of Neotropical birds. Tangara is divided into 13 species groups based on vocalizations, diet, geographic distributions, behavior, and appearance (Isler and Isler 1999). The Bay-headed Tanager is in Species Group 7, together with Rufous-winged Tanager (T. lavinia) and Rufous-cheeked Tanager (T. rufigenis). In a study of the relationships of Tangara species using DNA sequences, Burns and Naoki (2004) confirm the placement of Tangara gyrola in Species Group 7 and found that T. gyrola was most closely related to T. lavinia.  These results were later confirmed with molecular sequencing that included additional related species (Sedano and Burns 2010). Neither study sampled T. rufigenis, the other member of Species Group 7.

Because of the many morphological differences that occur across subspecies of T. gyrola, three distinctive groups, each of which perhaps merits species status, have been identified within the Bay-headed Tanager (Sibley and Monroe 1990, American Ornithologists' Union 1998; see Geographic Variation):

albertinae group (called the gyroloides group by Sibley and Monroe 1990 and the American Ornithologists' Union 1998), which includes most subspecies (bangsi, deleticia, nupera, catharinae, parva, and albertinae)

viridissima group (viridissima and toddi)

gyrola group (nominate gyrola)

The potential for multiple species to exist with this taxon also is suggested by molecular data. Burns and Naoki (2004) sequenced DNA from five individuals of Tangara gyrola, but all of these were from one of the three putative species, the albertinae group. Nevertheless, these samples showed significant sequence divergence, similar to that seen between many well-recognized species of Tangara. The five individuals  separated into two monophyletic groups: the first group was made up of two individuals from Central America, and the latter group consisted of three individuals from South America, east of the Andes. The average level of sequence divergence between the Central American and South American groups was approximately 4.6%, while the average level of sequence divergence within the individual groups was much lower, a little over 1%.  Thus, these genetic data suggest that even the albertinae group may consist of more than one species (Burns and Naoki 2004). Burney and Brumfield (2009) sequenced additional individuals of Tangara gyrola and also found evidence for genetic structure across populations. They sampled 4 individuals from the Napo region, 10 individuals from the Inambari region, and 4 individuals from the Rondonia region. Levels of sequence divergence were not reported; however, they found that 53.2% of the variation observed could be explained by differences observed among these three areas of endemism.

Recommended Citation

Burns, K. J. and C. Mireles (2010). Bay-headed Tanager (Tangara gyrola), version 1.0. In Neotropical Birds Online (T. S. Schulenberg, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/nb.bahtan1.01