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Grallaria guatimalensis

Scaled Antpitta

  • Order: Passeriformes
  • Family: Grallariidae
  • Polytypic 9 Subspecies

Authors: Greeney, Harold F., A. Rivera-Ortíz, C. Rodríguez-Flores, C. Soberanes-González, and M. C. Arizmendi

Identification

Summary

Antpittas (Grallaria) have a distinctive morphology: they are plump-bodied, with short tails and notably long tarsi. Scaled Antpitta is a medium sized antpitta with a broad buffy malar stripe, grayish crown and nape, and grayish or brownish olive upperparts. The underparts are tawny, with a white or creamy crescent across the upper breast. The feathers of the crown and back are narrowly tipped with black, giving it the scaled pattern for which this species is named. 

Similar Species

Scaled Antpitta is similar to several other species. Scaled Antpitta overlaps locally in Colombia and Ecuador with the very similar Moustached Antpitta (Grallaria alleni). These two species can be distinguished most reliably by differences in the pattern of the breast, in the width of the submoustachial streak, and in the shape and color of the bill (Krabbe and Coopmans 2000). Where these two species are sympatic, the breastof both species is mostly buff or olive brown, with feathers in the centre of the breast have a contrasting pattern. In Scaled (subspecies regulus), these feathers are pale buff (or, rarely, white), "with a noticeable difference in the distribution of white or buff between the inner and outer web of individual feathers, and with black on each side of the basal half of the shafts"; in Moustached, in contrast, these feathers are white, "with equal distribution of white on the outer and inner webs of each feather", and with the white forming "large, symmetrically elongated, narrowly black-edged spots extending onto the lower breast as thin, white to buff streaks surrounding the shafts" (Krabbe and Coopmans 2000). The submoustachial streak of Moustached is much larger than that of regulus, and always is white; the submoustachial streak of regulus is only half the width of that of Moustached, and only rarely is white (Krabbe and Coopmans 2000). 

Sclaed Antpitta also is similar to Variegated Antpitta (Grallaria varia), but there is little overlap between these two species. Varieaged Antpitta is larger, with a smaller white breast patch, and with the breast and flanks more or less streaked or spotted (the flanks are unmarked in Scaled Antpitta).

Vocalizations

The song of Scaled Antpitta is a rapid series of quavering, hollow notes lasting 2-7 seconds, slowly increasing in volume and pitch and then quickly becoming quieter at the end: cau, cau, cau-cau-caucaucaucau, cau. Krabbe & Schulenberg (2003) provide a detailed description of the song of regulus, stating that songs generally include 30-50 notes delivered so quickly (i.e. 14-17 per second) that it generally sounds like fewer. Delivery pace, after a few introductory notes, is rapid in the beginning, slowing towards the end.

Krabbe and Schulenberg (2003) note that the songs recorded in southern Peru (sororia) differ in having the first portion delivered at a much slower pace (only 6 notes per second), with the entire song slightly longer and being composed of only 18-23 notes; similarly, Lane (in Schulenberg et al. 2010) describes the song of sororia as "a slower-paced (6 notes/sec maximum) series of hooted notes that accelerates-decelerates at the loudest and highest-pitched notes, then accelerates again slightly: poo-poo-pu-pu'pu'pu-pu-POO-POO-POO-pu'pu".

Braun et al. (2003) describe three vocalizations of roraimae. The most frequently heard song was described as a long series of low hooting notes with three longer, more emphatic notes in the middle. They also occasionally heard a higher-pitched and somewhat screech-owl-like song. The third song, given most frequently at dawn, was a shorter-simpler version of the owl-like call described above.

Stiles and Skutch (1989) describe a low, pig-like grunt or croak given in alarm in Costa Rica.

Additional audio recordings of vocalizations of Scaled Antpitta can be heard at Macaulay Library and at xeno-canto.

Nonvocal Sounds

None reported.

Detailed Description (appearance)

Adult: Sexes similar. Forecrown with fine black scaling on a pale olive brownish background, blending to a gray crown and nape. Throat ochraceous- or tawny brown with narrow pale streaking; throat bordered by broad ochraceous or buffy malar stripes; below the throat is a crescent-shaped paler area, sometimes spotted with black to give a necklaced appearance. Loral area whitish or buffy. Auriculars olive brown with narrow streaking. Back and wing coverts similar in coloration to auriculars, with feathers edged in black to give it the scaled appearance reflected in its common name. Flight feathers and tail light brown. Under parts paler than rest, varying from pale tawny (ochraceiventris) to bright ochraceous or rufous (princeps).

Bare Parts

Iris: dark brown

Orbital skin: blue-gray

Bill: maxilla black, mandible grayish

Tarsi and toes: pinkish- or bluish gray

Measurements

Total length: 15 cm (Fjeldså and Krabbe 1990); 16-16.5 cm (Ridgely and Tudor 1994); 16.5 cm (Davis 1972): 17 cm (Angehr & Dean 2010); 18 cm (Meyer de Schauensee and Phelps 1978, Hilty and Brown 1986, Garrigues and Dean 2007); 18-18.5 (Meyer de Schauensee 1964); 19 cm (Blake 1953, Herklots 1961, Edwards 1972, French 1973); 20.3 (Edwards 1989)

Linear measurements (mm):

aripoensis (Hellmayr and von Seilern 1912):  adult male – Bill 33-34; wing 102-105; tail 32-36

adult female – Bill 32-33; wing 101-105; tail 34-37

princeps (Sclater and Salvin 1869): bill 33; wing 109; tail 43

chocoensis (Chapman 1917): culmen 22; wing 89; tail 28; tarsus 42

ochraceiventris (Nelson 1898): culmen 28; wing 114; tail 43; tarsus 47

carmelitae (Todd 1915): exposed culmen 21.5; wing 100; tail 38; tarsus 45

sororia (von Berlepsch and Stolzmann 1901): culmen 22.75; wing 107.5; tail 40.5; tarsus 45.5

roraimae (Chubb 1921): exposed culmen 23; wing 108; tail 39; tarsus 41

regulus (Sclater 1860): wing 102; tail 30; tarsus 41

Mass:

male (guatimalensis, n = 1) 94.6 g (Krabbe and Schulenberg 2003)


female (chocoensis, n = 1) 95 g (Krabbe and Schulenberg 2003)


male (regulus/sororia) 69.5-86 g (Krabbe and Schulenberg 2003)


female (regulus/sororia, n = 1) 79.8 g (Krabbe and Schulenberg 2003)


unsexed average (princeps) 98 g (Krabbe and Schulenberg 2003)


unsexed average (n = 6) 94.1 g (range 77.0-116.0 g) (Dunning 1993)

Molts

 No detailed information on timing or sequence of molting in Scaled Antpitta. Dickerman (1990) figures two male specimens which he considered to be in the later stages of their first pre-basic molt. Based on these and other specimens from the same Mexican locality, he described the subspecies binfordi; see discussion under Geographic variation. Dickey and van Rossem (1938) and Ryder and Wolfe (2009) suggest that, like other Grallaria, Scaled Antpittas go through only a partial preformative molt.

Geographic Variation

Scaled Antpitta is a highly variable species across its considerable geographic range, with somewhere between 7 and 11 subspecies recognized (Krabbe and Schulenberg 2003). The northernmost populations have been separated from nominate guatimalensis as subspecies mexicana (Sclater 1861; Jalapa, Veracruz, Mexico) based on larger size (from nominate) and paler underparts, but recent authors (Krabbe and Schulenberg 2003), and even Sclater (1877) himself, have questioned the validity of this distinction. Sclater’s (1861) original description of mexicana, in Latin, is as follows: "Similis G. guatemalensi, sed major, colore corporis infra dilutiore, ventre albicantiore, et remigibus alarum extus rufescentioribus. Long, tota 7.5, alae 5.0, caudae 2.0, tarsi 2.1 [inches]." Dickerman (1990) proposed the most recently described subspecies of Scaled Antpitta, binfordi, from 6000 ft. on the divide between Cuernavaca and Valley of Mexico, Morelos, Mexico. Krabbe and Schulenberg (2003) chose not to recognize this subspecies pending further analysis, but acknowledged that it might prove to be a valid taxon. Dickerman (1990) described binfordi as "similar to G. g. ochraceiventris in color but with marked breast band of vertical striping," stating that "the striping extends onto the belly in the first basic plumage."

The following subspecies were recognized by Krabbe and Schulenberg (2003):

1) G. g. guatimalensis (Prévost and Des Murs 1846). The nominate subspecies is distributed from eastern and southern Mexico (from northwest Veracruz and northern Oaxaca), southward and eastward to northern Nicaragua.

The original description in Latin of Prévost and Des Murs (1846): "G. suprà brunnea; subtùs rufescens; pectoris maculis aliquot semi-collaribus nigris", was quoted from de Lafresnaye (1842) referring to a Guatemalan specimen. They expand upon this original description by saying: "Tête et derrière du cou gris de fer, chaque plume cerclée régulièrement de noir; dos, manteau et couvertures alaires brun olivâtre écaillé légèment de noir; rémiges secondaires brunes; rémiges primaires et rectrices rousses; paupières blanchâtres; tout le dessous du corps, depuis le menton jusqu'aux couvertures inférieures de la queue d'un fauve roussâtre, les plumes de la gorge offrant quelques traits écailleux noirâtres."

2) G. g. aripoensis (Hellmayr and von Seilern 1912). This is the only subspecies not confined to the mainland, found only in Trinidad. Subspecies aripoensis shares the rich, deep coloration of princeps, but lacks a dusky throat patch, has buff-colored malar stripe, and an unmarked chest.

The original description, of a "large series" collected in 1912 in Trinidad is as follows: "Nearest to G. g. regulus Scl., from the Andes of Ecuador and Western Venezuela (Mérida), but smaller, with the underparts much brighter, deeper ferruginous, and the black squamate markings of the back decidedly broader".

3) G. g. princeps (Sclater and Salvin 1869). This Central American subspecies is confined to Costa Rican and western Panama. It is more richly colored than the nominate, with heavier black scaling on the upper parts.

The original description is as follows: "Supra oleaginea, plumis nigro marginatis; pileo et collo postico valde obscurioribus et cineraceo tinctis; loris et oculorum ambitu rufescentibus: alis obscure fuscis, extus et intus castaneo limbatis: cauda omnino fuscescenti-castanea: subtus saturate ferruginea, pectore paulo obscuriore, gutturis medii plumis nigro variegatis: rostro obscure corneo, mandibulae basi albicante; pedibus corylinis".

4) G. g. chocoensis (Chapman 1917). Very similar to subspecies princeps in its richer coloration, but chocoensis is darker overall, with a more olive crown and wings, and with the lores being somewhat rusty or darker (rather than whitish). It is confined to the northern Choco bioregion, in eastern Panama and northwestern Colombia.

Chapman’s (1917) original description is based on a male from Colombia in 1912 and is as follows: "Resembling Grallaria guatimalensis princeps (Scl. and Salv.) in general color but crown more olive, back richer, wings more olive less rufous, lores mixed rusty and blackish rather than whitish; size very much smaller."

5) G. g. ochraceiventris (Nelson 1898). Subspecies ochraceiventris is endemic to southern Mexico from Jalisco eastward to western Hidalgo and from southern Guerrero to southern Oaxaca. It is significantly paler than the nominate race, in particular on the underparts. It further differs by having narrow black scaling above and lacking dusky feathers on the throat.

The original description of the type, collected in 1897 at San Sebastian, Jalisco, Mexico, is as follows: "Feathers of crown and back olive-brown, shaded with fulvous, and narrowly margined with black; sides of crown, back of orbits, and nape olive-brown with a dark ashy shade most marked on sides of crown; forehead paler or more fulvous brown. Tertiaries and secondaries dull rusty brown; outer vanes of primaries shading from dull rusty brown to dull tawny brown on outer quills; wing coverts dull brown with shaft lines and spots of dull tawny brown at tips. Under coverts and axillars pale buffy; inner webs of quills at base still paler buffy, becoming grayish brown on outer half; tail and upper tail coverts light rusty brown. Lores and malar patch pale, dull grayish-white, shaded with dingy fulvous; under eyelids blackish; ear coverts dark olive-brown washed with blackish; chin, throat, and patch on middle of breast whitish washed with fulvous; feathers bordering breast-patch scantily black tipped; sides of throat, breast (except whitish patch), chest, and flanks dingy buffy."


6) G. g. carmelitae (Todd 1915). This subspecies was originally described as a subspecies of Variegated Antpitta (G. varia), but its correct affinities were later noted by Todd and Carriker (1922), who referred to it as G. regulus carmelitae. Subspecies carmelitae is known only from northern Colombia, in the Santa Marta Mountains and Perijá Mountains, southward to northern Boyacá. It differs from G. g. regulus only in being generally darker and browner (rather than olivaceous) on the upper parts and more brownish (than ochraceous) on the underparts. Krabbe and Schulenberg (2003) considered it to be doubtfully separable from regulus.

Todd (1915) described an adult male collected in 1914 at Pueblo Viejo, Colombia as follows: "Similar to Grallaria varia varia, but smaller, and posterior lower parts darker, more cinnamon rufous."

7) G. g. sororia (Berlepsch and Stolzmann 1901). Grallaria g. sororia is confined to southern Peru, south of Cuzco, and occurs in Bolivia southward and eastward to Santa Cruz. Krabbe and Schulenberg (2003) considered it to be doubtfully separable from regulus, differing only in whiter facial markings, a grayer back, and paler underparts (but note the different Vocalizations).

The original description of the type specimen in Latin is as follows: "G. dorso pileoque anteriore brunnescenti griseo-olivaceis, pileo posteriore nuchaque griseis, plumarum apicibus nigro marginatis, marginibus in dorso lalioribus in pileo angustioribus, tectricibus auricularibus gulaque obscure olivaceo-brunneis, regione infraauriculari et regione malari albo et brunneo variis, torque juguli semilunari superiore albo, inferior nigro (plumarum apicibus nigris); pectore laleribusque corporis pallide rufescenti-brunneis maculis fuscis irregularibus vix conspicuis instructis, abdomine medio pallidiore fulvo; hypochondriis crisso tectricibusque subcaudalibus et subalaribus necnon remigum marginibus internis laete fulvorufis; alis extus rectricibusque rufescenti olivaceo-brunneis; maxilla cornea, niandibula pedibusque carneo-brunneis."

8) G. g. roraimae (Chubb 1921). This subspecies is confined to the tepui region of southern Venezuela and adjacent areas of northern Brazil and western Guyana. It is similar to regulus, but has a grayer crown.

Chubb (1921) describes this subspecies as "differ[ing] from the type of G. r. regulus in being more grey on the top of the head, nape, and hind-neck; paler and more olive-brown on the back and the dark fringes to the feathers less pronounced; paler and more cinnamon-rufous on the outer aspect of the flight-quills; ear-coverts darker; throat more streaked with white or ferruginous; fore-neck ferruginous intermixed with black, instead of uniform ochreous brown; breast, abdomen, and under tail-coverts paler and brighter ferruginous; and the larger size."

9) G. g. regulus (Sclater 1860). Sclater describes this species from a single specimen collected in Ecuador. Subspecies regulus is one of the more widely distributed subspecies, found from northwestern Colombia southward along the western slope of the Andes southward through Ecuador to Cajamarca, Peru. On the eastern Andes it is found from western Venezuela (Mérida) southward through Colombia and eastern Ecuador to central Peru. It is generally smaller than other subspecies, usually has a buffier malar stripe and facial crescent (only occasionally white in some individuals), a dusky throat, pale tawny (rarely white) striping on a dark brown breast. The underpart coloration fades to tawny on the belly and crissum.

Sclater’s original (1860) description in Latin is as follows: "Brunnescenti-olivacea, pileo cinerascentiore; dorsi plumis nigro circumcinctis; alis nigricantibus extus brunneo limbatis; cauda brevissima unicolore brunnea: subtus saturate ferruiginea, gutture et pectore nigricantiore perfusis; torque gutturali pallide cinnamomeo, hujus plumarum apicibus nigris: rostro comeo, supra obscuriore: pedibus corylinis: tectricibus subalaribus ventre concoloribus".

Systematics

Grallaria guatimalensis is probably most closely related to Grallaria varia (Variegated Antpitta) (Krabbe et al. 1999), with which it shares many plumage characteristics and near which it is traditionally placed in linear sequences (Cory and Hellmayr 1924, Peters 1951, Remsen et al. 2013). It is certainly a member of the Grallaria subgenus, along with G. squamigera (Undulated Antpitta), G. gigantea (Giant Antpitta), G. excelsa (Great Antpitta), G. varia, G. alleni (Moustached Antpitta), G. chthonia (Tachira Antpitta), and G. haplonota (Plain-backed Antpitta) (Lowery and O’Neill 1969).

Recommended Citation

Greeney, Harold F., A. Rivera-Ortíz, C. Rodríguez-Flores, C. Soberanes-González, and M. C. Arizmendi. 2013. Scaled Antpitta (Grallaria guatimalensis), 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=402441