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Eucometis penicillata

Gray-headed Tanager

  • Order: Passeriformes
  • Family: Thraupidae
  • Polytypic 7 Subspecies

Authors: Baker, Carly S., and Kevin J. Burns

Identification

Summary

The Gray-headed Tanager is a brightly colored, moderately sized tanager. It has olive to yellow upperparts, bright yellow underparts, and a conspicuous gray head and crest (Hilty and Brown 1986).

Similar Species

Gray-headed Tanagers may be mistaken for female White-shouldered Tanagers (Tachyphonus luctuosus), female Black-throated Shrike-Tanagers (Lanio aurantius) or Gray-hooded Bush-Tanagers (Cnemoscopus rubrirostris), all of which share a similar plumage pattern. The Gray-headed Tanager can be distinguished from these species by its gray crest. In addition, the Gray-headed Tanager typically forages closer to the ground than these species; it is smaller than the Black-throated Shrike-Tanager and larger than the White-shouldered Tanager and Gray-hooded Bush-Tanager (Ridgely and Tudor 1989, Howell and Webb 1995, Restall et al. 2007). There also is little or no overlap in elevational distribution with the bush-tanager, which occurs above 1900 m in the Andes.

Vocalizations

Call notes of the Gray-headed Tanager have been described as warbler- and hummingbird- like and include a sharp, high-pitched, unmusical chewt. These high-pitched calls can be difficult for predators to detect yet are transmitted poorly in the forest understory (Willis 1985). Call notes often are repeated at a rate of one note per second (Isler and Isler 1999). A possible alarm call may be a low-to-moderate rattle (Slud 1964, Isler and Isler 1999), often repeated several times (Willis 1985). Other calls include "a squeaky, high, thin tseet, often repeated 2-3 times [and]  a high-pitched, thin chip or pit, sometimes repeated incessantly" (Costa Rica; Stiles and Skutch 1989); a schip alarm note (eastern Colombia; Hilty and Brown 1986); and a "high, sibilant, descending series 'swee-swee-swee-swee' " (Lane, in Schulenberg et al. 2007).

Only males sing (Willis 1985) and have been observed singing while foraging, nest building and perching, yet do this sparingly (Skutch 1989, Restall et al. 2007). Songs of the Gray-headed Tanager are a jumbled series of sputtering notes and described in the literature as high, buzzing notes (Ridgley and Tudor 1989, Isler and Isler 1999, Restall et al. 2006), yet Skutch (1954) described it as soft with a smooth flow. The song of the Gray-headed Tanager varies geographically (Isler and Isler 1989). The song in Costa Rica is described as "a high, thin, rather sibilant medley, whichis whichis whicheery whichis whichu', tsee tseep SEEUr tsp-tsp tseeur tsp-tsp seeur ts-suur, etc." (Stiles and Skutch 1989). In Aragua, northern Venezuela, the song is described as "a high, buzzy pzzzt-buzzt-buzzt-fzzzt" (Hilty 2003). The song in Peru is "a loud, strident series of jerky, ringing notes interspersed with high sibilant sounds, seeps, and chips" (Lane, in Schulenberg et al. 2007). In south central Brazil, the song is described as "a sequence of high whistles with 2nd part of stanza descending, tsee, tsee, tsee, tsi, tsi, tsi, tsi, tsi, tsi, sometimes more varied and prolonged" (Sick 1983).

Nonvocal Sounds

None reported.

Detailed Description (appearance)

Adults: Overall, both males and females are olive yellow with a gray head. The wings are yellowish olive with darker margins, and underwing coverts are yellowish. Its namesake gray head has a crest of white feathers tipped with gray. The crest is usually laid flat against the head but can be raised when the bird is agitated (Ridgely and Tudor 1989). The chest is a conspicuous bright yellow and the throat is pale white. The tail is pale brown with yellowish olive margins. Willis (1985) noted that the yellow and green pigments of this species blends well with dappled foliage; however, the yellow underparts are more conspicuous closer to the ground. The sexes of the Gray-headed Tanager are similar, but males of at least one subspecies (E. p. albicollis) have a longer crest (Ridgely and Tudor 1989). An analysis of coloration using an avian visual model confirms the lack of sexual dichromatism for most plumage regions; however, the belly and flanks differ slightly between males and females (A. J. Shultz and K. J. Burns, unpubl. data).

Immatures and subadults have a reduced crest and usually lack a gray head (Schulenberg et al. 2007). Instead, the head is greenish olive and the throat olive-yellow (Isler and Isler 1999). Nestlings less than 12 days old have pink skin with sparse gray feathers (Skutch 1989). At about seven months, young are finishing wing molt and look similar to adults (Willis 1985).

Bare Parts

Bill: hazel and white underneath with a large rounded notch on upper mandible, subconical, compressed, and much shorter than rest of head (Clark 1913).

Iris: bright reddish brown (Wetmore et al. 1984).

Tarsi and toes: pale brown; claws dull slate (Ridgway 1902, Wetmore et al. 1984).

Measurements

Total length: 16-17 cm (Isler and Isler 1999)

Mass, both sexes: mean 27 g (range 22.5-35.0 g; n=52; Isler and Isler 1999)

 

 

Table 1- Length measurements of various parts of the body, measurements in mm, from Ridgway (1902).
Sex Body Wing Tail Culmen Depth of Bill Tarsus Middle Toe
Male 156 89.9 75.9 12.7 6.9 21.8 15
Female 153.8 83.8 72.4 14 6.9 22 15.7

Table 2- Length measurements of various parts of the body, measurements in mm, specimens from Costa Rica and Panama, from Wetmore et al. (1984).

Sex Wing Tail Culmen (from base) Tarsus
Male 89.5 76.8 17.1 21.3
Female 86.3 74.2 16.9 21.3


 

Molts

Willis (1985) reported the timing of molt from young to adult plumage for the following locations: Central America (late May-late October), northern Colombia and Venezuela (April-early September), southern Brazil (mid April-late June).  For adult birds, molt takes about four months and timing varies geographically (Willis 1985).  From Mexico to northern Colombia and Venezuela, adult birds begin molt in June to August and end molt from October to December (Willis 1985). From Mato Grosso to São Paulo, molt begins in November or December and lasts to March, while birds in Amazonia and Guyana molt from February to July (Willis 1985).

Geographic Variation

Seven subspecies are usually recognized (Storer 1970). In general, subspecies that are west of the Andes are smaller, have a reduced crest, and a darker head (Ridgely and Tudor 1989).:

E. p. pallida: Richer yellow on chest, head and throat are a darker gray (Isler and Isler 1999). Occurs southeastern Mexico to eastern Guatemala.

E. p. spodocephala: Underparts are a deeper, orangish yellow (Isler and Isler 1999). Nicaragua, and the Pacific Slope of Costa Rica.

E. p. stictothorax: Head is greenish olive instead of gray, throat is yellowish olive,and lacks a prominent crest (Isler and Isler 1999, Skutch 1954). Southwestern Costa Rica and western Panama.

E. p. cristata: Pale gray crest, olive-tinged throat (Restall et al. 2006). Eastern Panama, northern Colombia.

E. p. affinis: Long crest, but shorter than E. p. cristata and E. p. penicillata and with less white on the tips, paler throat (Isler and Isler 1999, Restall et al. 2006). Northern Venezuela.

E. p. penicillata: Has the largest crest, a white chin and throat (Restall et al. 2006). Southeast Colombia south to eastern Peru, and east to the Guyanas and northern Brazil.

E. p. albicollis: Head, throat, and the very long crest are a "buffy gray" (Isler and Isler 1999). Eastern Bolivia, northern Paraguay, northeast Argentina, and south central Brazil.

Burns and Racicot (2009) sequenced DNA from three individuals of the Gray-headed Tanager, two from adjacent populations in Bolivia and one from Panama. The two Bolivian individuals were very similar to each other, but the Panamanian sample differed in 4.8% of the base pairs sequenced, a level higher than that observed between many avian species and genera. Thus, multiple independent evolutionary units that perhaps represent distinct species may exist within the Gray-headed Tanager.

Systematics

The Gray-headed Tanager is the only member of the genus Eucometis. Recent phylogenetic analyses based on mitochondrial DNA show that it belongs to a large clade of lowland tanagers that include all members of the genera Ramphocelus, Tachyphonus, Coryphospingus, Rhodospingus, Lanio, and Trichothraupis (Burns and Racicot 2009). Among these species, its closest relative is the Black-goggled Tanager (Trichothraupis melanops), with which it shares a number of features including general  size, presence of a crest, and other plumage characteristics (Willis 1985, Isler and Isler 1999, Burns and Racicot 2009).  In addition, Willis (1985) noted several common behaviors of these two species, including army-ant following. Based on these similarities and complementary geographic distributions, Willis (1985) suggested placing the Black-googled and Gray-headed tanagers in the same genus, Trichothraupis.  Although this suggestion has not yet been adopted, the DNA phylogeny (Racicot and Burns 2009) agree with Willis's assessment.  

Recommended Citation

Baker, Carly S., and Kevin J. Burns. 2010. Gray-headed Tanager (Eucometis penicillata), 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=593196