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SPECIES

Tawny Antpitta Grallaria quitensis Scientific name definitions

Harold F. Greeney and Andrew J. Spencer
Version: 2.0 — Published September 1, 2023

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Plumages, Molts, and Structure

Plumages

Like other antpittas (Grallariidae), the Tawny Antpitta has 10 functional primaries (numbered distally, p1–p10), 9 secondaries (numbered proximally s1–s9 (including three tertials, s7–s9), and 12 rectrices (numbered r1–r6 on each side of the tail) (4, 5). The following plumage descriptions are primarily from Krabbe and Schulenberg (6) and Greeney (7,8), along with examination of Macaulay Library images. See Molts for molt and plumage terminology. The following plumage descriptions refer to nominate quitensis. For adult plumage descriptions of other subspecies, see Subspecies. For descriptions of the natal down and first-cycle plumages of other subspecies, if known, see Geographic Variation. So far as is known, the genders are similar in all plumages. Timing of plumages appears to occur year round although in Ecuador, Natal and Juvenile Plumage may peak in September–January and subsequent plumages may most often be fresh in February and worn in November coinciding with breeding seasonality (see Breeding: Phenology)

Natal Down

Present in the nest and at fledging (see also Young Birds). The nestling plumages have not previously been described in detail but figured by Greeney (9). The first (nessoptile) natal down is sparse and pale gray to blackish. A few days after hatching, nestlings develop a dense coat of plumose (fluffy), second (mesoptile) post-natal down, developing last on the head. Above, they are distinctly and finely barred tawny buff and dark gray to gray brown. Barring is narrower and better defined on the crown, tending towards tawny with fine blackish barring. Barring continues onto nape, but becomes slightly less distinct, with scattered tawny-tipped feathers creating a somewhat more spotted look on hindcrown and nape. The barred pattern of the back continues across the throat, upper breast, and sides of the breast. The pattern gradually fades onto the flanks and lower breast, as the percentage of dark diminishes and the amount of pale increases. The dark markings fade from gray brown to pale gray, the tawny fades gradually to buff. Most or all patterning is lost on the belly, which is largely pale buff to white and whitish on the lower belly and vent.

As the young fledge from the nest they are still covered in their plumose second post-natal down, and their appearance is largely unchanged during the first few days post fledging. During the next few weeks, as their juvenile rectrices and flight feathers finish emerging from their sheaths, their appearance changes gradually, with the amount of dark increasing and the barring in most areas becoming coarser and less distinct. They retain, however, their downy, plumose appearance, although the precise timing of this post-fledging plumage development remains unknown and appears to be somewhat variable with respect to when different areas of of the upperparts lose their downy, barred, fledgling appearance. In general, older fledglings have the forecrown to the nape and upper back finely barred ochraceous or tawny buff and blackish. The back and rump are coarsely barred tawny ochraceous and black, but with small, irregularly placed patches of juvenile (olive brown) contour feathers, especially on the scapulars. Older fledglings have whitish lores and an indistinct whitish eye ring, washed with tawny olive. The superciliary and auricular regions and the sides of the head behind the eyes are tawny olive to tawny brown. The auriculars and malar areas are similar in color but duskier, approaching blackish in some individuals, especially on the posterior auriculars and lower sides of the face. The central throat is pale tawny bordered white, creating a fairly distinct submalar streak that may or may not extend rearward. The crown, nape, and sides of the neck are finely barred, becoming brighter tawny buff towards the throat and more thickly barred blackish. This barring continues across the breast just below the throat and onto the sides and central breast. The plumose plumage of the breast is variably interrupted by tawny juvenile contour feathers. The remaining underparts are usually still mostly in downy plumage, as described for nestlings, somewhat mottled tawny buff, white, and gray. The long, plumose feathers of the vent and flanks are clean tawny buff.

Juvenile (Fist Basic) Plumage

Present from 1-3 months following fledging. In contrast to fledglings, which are largely plumose with scattered adult-like feathers, juveniles are now largely covered in juvenile contour feathers, with only patches of down remaining. The crown is dusky olive with tawny olive edges, of varying thickness, on the feathers, giving an indistinctly barred or scaled appearance. The forecrown is more tawny olive and less dusky. The face is dark tawny with scattered dusky feathers, especially on the ear coverts and lower malar; the cheeks and upper malar are slightly speckled. Feathering is whitish around the eyes and on the lores. The hindcrown, nape, and upper back are tawny buff, finely barred black (not streaked as in alticola), with scattered adult feathers throughout. The back is as described for Definitive Basic Plumage, sometimes with faint dusky scaling or barring. The uppertail coverts are buffy rufous to rusty buff, the thighs tawny buff. The juvenile upperwing secondary coverts are slightly more tawny olive than later feathering and with buff tips, the greater coverts dark grayish basally, gradually becoming warmer, tawny brown distally. The upperwing primary coverts are dusky brown, washed with brown. The primaries are distinctly tawny on the anterior margins, dark on the posterior webs, and edged pale olive buff on their leading margins. The pale margins are more extensive on the secondaries, extending onto the feather tips and becoming pale buff. Their tips are narrowly edged with bright tawny, with a narrow black subterminal bar. The tertials and inner secondaries are broadly tipped with tawny buff surrounding indistinct black markings forming partial bars or spots. These black markings become reduced or absent on the outer secondaries. The rectrices are tipped with pale buff when fresh but this begins wearing off at this age. The chin and central throat is whitish, becoming tawny lower and on the sides. The underparts are overall much like those of later plumages but with variable and usually asymmetrical patches of dusky black barring, especially on the breast-sides and flanks (7, 8). The undertail coverts and feathers of the lower flanks and at the sides of the rump are filamentous and buffy with dark gray bases. This description is largely congruent with a juvenile described by Domaniewski and Sztolcman (10). Greeney (8) described the juvenile plumage of subspecies alticola (see Geographic Variation), but the juvenile plumage of atuensis has yet to be described. .

Formative Plumage

Formative Plumage resembles Definitive Basic Plumage but the crown is dusky olivaceous, the forecrown more tawny olive and less dusky. The hindcrown and nape sometimes show a few scattered tawny buff feathers, finely barred with black. The back sometimes show faint dark scaling or barring created by dusky feather edges. The chin and central throat are whitish, becoming tawny lower and on the sides. The underparts are overall like adults but can retain a few small traces of dusky black barring, especially on the sides of the breast. Retained juvenile greater coverts are usually found in the outer portions of the tract and have large triangular buff tips, contrasting with replaced median and inner greater coverts that lack or have smaller buff tips. The retained greater alula is worn and tipped buff. Juvenile primary coverts are brownish and relatively worn with distinct pale tips when fresh. One to three tertials appear to be frequently replaced, the inner formative feathers being grayer and contrasting with the more worn outer feathers and secondaries. Juvenile primaries and secondaries are faded and lack gloss. Retained juvenile rectrices are relatively narrow and worn, with tawny or buff tips when fresh, that usually wear off during the first year.

Definitive Basic (Adult) Plumage

The upper parts are generally pale brown to olive brown. The lores are pale buff blending with a whitish ocular region, while the sides of the head are dull olive brown to rufous olive, mixed with blackish. The crown and back are washed slightly with gray, while the rump tends to be browner, sometimes approaching dull rufous to clay-colored. The wings and tail are similar in color to the back, with the leading edge of the outer primaries pale buff or tawny and the trailing vane blackish to blackish olive. Below, the underparts are generally tawny brown, with indistinct white mottling, becoming whitish in the center of belly, paler tawny on the flanks, and a richer rufescent tawny on the undertail coverts. The chin and throat are whitish.

Definitive Basic Plumage is separated from Formative Plumage by having wing and tail feathers uniform in quality and relatively broad, fresh, and glossy. Molt limits among upperwing coverts are lacking, the outer greater coverts lacking buff (or occasionally with variable buff tips that are usually not as consistently large and triangular as found on retained juvenile feathers of Formative Plumage). The primary coverts are dark, glossy, and lack buff tips. Primaries, secondaries, and rectrices are dark, glossy, and relatively broad and truncate at the tips, the rectrices not distinctly tipped buff.

Molts

General

Molt and plumage terminology follows Humphrey and Parkes (11) as revised by Howell et al. (12). Under this nomenclature, terminology is based on evolution of molts along ancestral lineages of birds from ecdysis (molts) of reptiles, rather than on molts relative to breeding season, location, or time of the year. Timing of molts likely relates to timing of breeding, which appear to occur year round within the entire population, although in Ecuador, Prejuvenile and Preformative Molts may peak in November–February and Preformative and Prebasic Molts may peak in February–April, following the peak breeding season (see Breeding: Phenology) although molting at other times occurs. Molts during the first cycle and the progression of plumage development are not described for the Tawny Antpitta, but available information (8) along with examination of Macaulay Library images, indicates that it exhibits a Complex Basic Strategy (cf. 12, 13), including incomplete prebasic molts and a partial preformative molt but no prealternate molts (14, 15, 8, 5). Like other antpittas, the molts of the Tawny Antpitta during the fledging and post-fledging periods appear to be rather prolonged, making it difficult to align with proposed terminologies used to describe passerine molts and plumages (11, 14, 16, 17, 18). Here it is assumed that most individuals fledge primarily in the second (messoptile) post-natal down, followed quickly by prejuvenile molt of contour feathers and preformative molt of contour feathers, upperwing coverts, and (often) tertials. See images under Natal Down, Juvenile, and Formative Plumages. The corresponding age classes proposed by Greeney (8), which aim to estimate age since fledging based on plumage and behavior, include fledgling (largely still in post-natal down), juvenile (first basic; gape and sometimes tomia and parts of bill still orange, often still fed by parents), and subadult (formative; retained immature upperwing coverts), with individuals that do not clearly fit into one of these categories, based in part on plumage and in part on behavior, referred to as “transitional" or as transitioning from one age-category to the next (e.g., juvenile transitioning). An alternative terminology could designate the plumage at fledging as juvenile and the first-post fledging molt as auxiliary preformative (see 18: 16-17) resulting in an auxiliary formative plumage. Further study is needed on the evolution of molts during this period in antpittas.

Prejuvenile (First Prebasic) Molt

Complete, often beginning at fledge and completing within 1 month of fledging. While still in the nest, the juvenile rectricies older nestlings are just beginning to break their sheaths (see images under Natal Down) and remain largely sheathed until fledging. Just before or just after fledging the contour feathers begin to replace the plumose post-natal down, beginning on the face, crown, and nape and secondarily on the mantle, upper back, and upper breast; at this time individuals begin to take on a very messy and “mangy” appearance, a plumage phase termed Fledgling Transitioning (8). The transition from the fledgling plumage, which is composed largely of plumose post-natal down (8) to juvenile plumage is particularly gradual and often asymmetrical. By an (estimated) age of around 1 month post-fledge, they reach the Juvenile Plumage phase, in which most individuals are now largely covered in their juvenile feathers, but can retain post-natal down on the belly, flanks, and sometimes lower breast. Individuals are frequently encountered with down on one side of their nape and not the other, or with only one half of their breast still in down, with nearly fully adult-like plumage on the opposite side (8). In fact, it is nearly impossible to find two immediately post-fledging individuals that look exactly the same. Patches of down may also persist among lesser wing coverts, mantle or breast breast feathers, and/or occasionally on the sides of the crown above the eyes. It is unclear if there is a pause in molt at this stage, and this likely varies between individuals, but it seems almost certain that their juvenile feathers, primarily or entirely the spotted and streaked feathers of the head, nape, and breast, start to be replaced during the Preformative Molt before the plumage of their lower hindquarters completes the Prejuvenile Molt.

Preformative Molt

Partial, appearing to occur within a few weeks of leaving the nest. The Preformative Molt, as in other antpittas (14, 5), appears typically to include most to all body feathers (some juvenile body feathers are possible retained in occasional individuals) and upperwing lesser coverts, most to all median coverts, often 4–5 inner greater coverts, and 1–3 tertials, but not the primaries, primary coverts, greater alula, other secondaries (besides tertials) or rectrices. Overall, it appears that the last clearly juvenile plumage characteristics to be lost are the traces of barring on the nape, followed by the replacement of the patterned upperwing coverts. The barred, immature formative plumage is retained the longest on the sides of the neck and, so far as is known, the upperwing coverts are the last feathers to be molted before attaining definitive (adult) plumage (8, 5).

Definitive Prebasic Molt

Complete, likely occurring 1-3 months following breeding, as in most passerines. Very few images of birds replacing flight feathers occur among Macaulay Library images, indicating that individuals are retiring during these periods. Sequence of feather replacement not studied although preliminary evidence and that from other antbirds (5) indicates that it is typical of passerines; primaries being replaced distally from innermost p1 to outermost p10, secondaries being replaced bilaterally from the second tertial (s8) and distally from the outermost (s1), and rectrices generally being replaced distally (from innermost r1 to outermost r6) on both sides of the tail.

Bare Parts

The following descriptions are based primarily on those of Greeney (8) along with examination of Macaulay Library images. See Plumages for additional images depicting bare part color changes with age.

Bill and Gape

In hatchlings and nestlings the bills are generally bright orange, brightest along the tomia and gape; their mouth linings are bright, rich, orange, or crimson orange, and the tip of the maxilla bears a bright white egg tooth. The bright whitish egg tooth is retained until fledging. At this time the tomia are paler and yellow orange; the expanded rictus and mouth lining are bright orange. At fledging and in juveniles the bill becomes overall mostly dusky orange, the mandible blackish on culmen and more orange on tomia and at tip; mandible slightly duskier near tip than basally; rictus still somewhat expanded and bright orange. Within 2–3 mo of fledging the maxilla becomes black with a paler tip and tomia; mandible black, dusky orange on tomia and central ridge, especially closer to base. During the first year (while in Formative Plumage) the bill gradually becomes mostly black, slightly more brownish on tomia and paler at tip of the maxilla. Individuals of this age have variable amounts of orange at the base of the bill and, especially, at the gape, that decreases with age; some retain a bright orange rictus that is now only slightly inflated. In adults the bill is black to blackish gray, sometimes paler (brownish) near base of mandible (19).

Iris and Bare Skin

In nestlings and juveniles the iris is dark brown. In adults it can become more chestnut brown (6, 7, 8). In hatchlings the exposed skin is generally pinkish, dusky on the upperparts, pinker below, and orange pink on the throat and face, becoming dark gray to blackish before fledging. The orbital skin can be pinkish until fledging, becoming dark grayish thereafter.

Tarsi and Toes

In hatchlings the legs and feet are bright pink to dusky pink. The nails are distinctly orange, tipped with yellow orange. In nestlings the tarsi are dusky anteriorly, fading to pinkish posteriorly and darkening to gray or blackish on the toes; nails become dusky yellow. At fldeging the legs and feet are dusky pink to brownish pink and the nails are distinctly yellow, and in juveniles the legs and feet become grayish to pale violet-gray and the nails become yellowish gray. In adults leg and foot coloration has been described as pale to dark brownish, grayish to blackish, olive-gray (20), and brownish gray (6).

Measurements

General Size

  • Total length – 16–18 cm. 16 cm (21); 16 cm (alticola, 20); 16.0–16.5 cm (3); 16–18 cm (6, 2); 17 cm (quitensis, 22); 17 cm (23); 18 cm (24); 18 cm (atuensis, 25); 18 cm (quitensis, 20).
  • Mass – 58–81 g. Krabbe and Schulenberg (6) gave the range of weights of males as 62–78 g and of females as 58.5–81.2 g, but did not specify sex or subspecies.

Linear Measurements

Grallaria quitensis alticola (adults)

  • Wing length – 93 mm (n = 1 male, holotype, 26); 87 mm (n = 1 male, 27); mean 98.0.8 ± 7.1 mm (n = 4, sex unknown, 8).
  • Tail length – 50 mm (n = 1 male, holotype, 26); 44 mm (n = 1 male; 27).
  • Bill length [total culmen] – 24 mm (n = 1 male; 27).
  • Bill length [exposed culmen] – 21 mm (n = 1 male, holotype, 26); 19.6 ± 0.6 mm (n = 4, sex unknown; 8).
  • Bill length [from nares] – 13.9 ± 0.3 mm (n = 5, sex unknown; 8).
  • Bill depth [at nares] – 6.9 ± 0.2 mm (n = 4, sex unknown; 8).
  • Bill width [at nares] – 5.4 ± 0.3 mm (n = 4, sex unknown; 8).
  • Bill width [at base of mandible] – 7.9 ± 0.3 mm (n = 4, sex unknown; 8).
  • Tarsus length – 46 mm (n = 1 male, holotype; 26); 44.2 ± 1.7 mm (n = 4, sex unknown; 8).

Grallaria quitensis alticola (subadults)

  • Wing length – No data.
  • Tail length – No data.
  • Bill length [from nares] – 13.2 mm, 13.2 mm (n = 2, sex unknown; 27, 8).
  • Tarsus length – 45.1 mm, 46.1 mm (n = 2, sex unknown; 27, 8).

Grallaria quitensis quitensis (adults)

  • Wing length – Males: 97.6 ± 5.1 mm (n = 26, males; 8); mean 94 mm, range 92–98 mm (n = 11, males; 25); 96.8 ± 4.7 mm (n = 8, females; 8).
  • Tail length – Males: 45.3 ± 3.3 (n = 7, males; 8); range 48–58 mm, mean 53.4 mm (n = 11, males; 25); mean 46.6 ± 2.2 mm (n = 5, females; 8).
  • Bill length [total culmen] – 27.0 ± 1.0 mm (n = 7, males; 8); 28.1 ± 1.5 mm (n = 4, females; 8).
  • Bill length [exposed culmen] – 21.9 ± 1.1 mm (n = 29, males; 8); 22.6 ± 1.2 mm (n = 8, females; 8).
  • Bill length [from nares] – mean 15.4 ± 0.7 mm (n = 35, males; 8); mean 15.4 ± 0.7 mm (n = 18, females; 8).
  • Bill depth [at nares] – mean 8.3 ± 0.7 mm (n = 14, males; 8); 8.5 ± 0.4 mm (n = 5, females; 8).
  • Bill width [at nares] – mean 6.7 ± 0.6 mm (n = 15, males; 8); 6.8 ± 0.5 mm (n = 6, females; 8).
  • Bill width [at base of mandible] – mean 8.8 ± 0.7 mm (n = 14, males; 8); 9.1 ± 0.8 mm (n = 6, females; 8).
  • Bill width [at gape] – mean 12.7 ± 2.4 mm (n = 13, males; 8); mean 14.6 ± 0.5 mm (n = 4, females; 8).
  • Tarsus length – mean 48.5 ± 2.4 mm (n = 44, males; 8); mean 47.5 mm, range 45‒50 mm (n = 11, males; 25); mean 48.5 ± 2.1 mm (n = 11, females; 8).
  • Middle toe length – mean 31.7 mm, range 30–33 mm (n = 11, males; 25).

Grallaria quitensis quitensis (juveniles)

  • Wing length – mean 100.6 ± 5.2 mm (n = 5, males; 8); mean 97.4 ± 4.0 mm (n = 5, females; 8).
  • Tail length – mean 52.2 ± 4.6 mm (n = 3, males; 8); mean 45.7 ± 5.0 (n = 3, females; 8).
  • Bill length [total culmen] – total culmen, 25.2 mm (n = 1, males; 8); 26.6 ± 1.1 mm (n = 3, females; 8).
  • Bill length [exposed culmen] – mean 19.8 ± 2.1 mm (n = 6, males; 8); mean 21.6 ± 1.3 mm (n = 8, females; 8).
  • Bill length [from nares] – mean 14.7 ± 1.2 mm (n = 9, males; 8); mean 14.6 ± 0.5 mm (n = 9, females; 8).
  • Bill depth [at nares] – mean 7.9 ± 1.0 mm (n = 5, males; 8); 7.7 ± 0.5 mm (n = 3, females; 8).
  • Bill width [at nares] – mean 8.3 ± 3.9 mm (n = 5, males; 8); 7.1 ± 0.6 mm (n = 4, females; 8).
  • Bill width [at base of mandible] – mean 8.5 ± 0.3 mm (n = 4, males; 8); 8.6 ± 0.6 mm (n = 4, females; 8).
  • Bill width [at gape] – mean 13.0 ± 1.9 mm (n = 2, males; 8); 13.4 ± 1.4 mm (n = 6, females; 8).
  • Tarsus length – 48.9 ± 2.1 mm (n = 9, males; 8); 47.9 ± 1.6 mm (n = 9, females; 8).

Grallaria quitensis quitensis (fledglings)

  • Wing length – 103 mm, 98 mm (n = 2, sex unknown; 8).
  • Bill length [exposed culmen] – 5.1 mm, 18.5 mm (n = 2, sex unknown; 8).
  • Bill length [from nares] – 11.0 mm, 13.3 mm (n = 2, sex unknown; 8).
  • Bill depth [at nares] – 6.4 mm (n = 1, sex unknown; 8).
  • Bill width [at nares] – 6.1 mm, 5.8 mm (n = 2, sex unknown; 8).
  • Bill width [at base of mandible] – 8.9 mm, 8.0 mm (n = 2, sex unknown; 8).
  • Tarsus – ​​​​​​​49.5 mm, 46.6 mm (n = 2, sex unknown; 8).

Grallaria quitensis quitensis (nestlings)

  • Tarsus length – 17.9 mm (n = 1, five days old; 8); 34.0 mm, 35.1 mm (n = 1, one day pre-fledging; 8). See also Domaniewski and Sztolcman (10) and Carriker (25).

Grallaria quitensis atuensis (adults and subadults)

  • Wing length – Males: 87 mm (n = 1, male, holotype; 25); 91 mm (n = ?, males; 28); 87.9 ± 3.1 mm (n = 11, males; 8); mean 85.8 ± 2.2 mm (n = 4, females; 8).
  • Tail length – ​​​​​​​52 mm (n = 1, male, holotype; 25).
  • Bill length [exposed culmen] – 19 mm (n = ?, males; 28); 21.5 ± 0.8 mm (n = 10, males; 8); 21.3 ± 0.8 mm (n = 6, females; 8).
  • Bill length [from nares] – 14.3 ± 0.4 mm (n = 10, males; 8); 13.4 ± 0.3 mm (n = 6, females; 8).
  • Tarsus length – ​​​​​​​40 mm (n = 1, male, holotype; 25); 41 mm (n = ?, males; 28); 40.9 ± 1.4 mm (n = 11, males; 8); 41.6 ± 1.3mm (n = 6, females; 8).
  • Middle toe length –​​​​​​​ 28 mm (n = 1, male, holotype; 25).

Mass

Grallaria quitensis alticola (adults)

  • Sex unknown – 47 g (n = 1; 29). No further data.

Grallaria quitensis quitensis (adults and subadults)

  • Males – 66 g, 67.2 g, 69 g, 69.5 g, 70 g, 71 g, 71 g, 72 g, 72g, 72.3 g, 73 g, 73 g, 74 g, 74 g, 78 g (n = 15; 8); 76 g (n = 1; 29).
  • Females – 61 g, 65 g, 67 g, 70 g, 71 g, 75 g, 81.2 g (n = 7; 8); 82.5 g, 82 g (n = 2; 29).
  • Sex unknown – 65 g, 69 g, 71.5 g, 75 g, 76 g, (n = 2; 29).

Grallaria quitensis quitensis (juveniles)

  • Males – 68.6 g, 70.8 g, 75 g g (n = 3; 8).
  • Females – 60 g (n = 1; 8).
  • Sex unknown – 50 g (n = 1, "immature;" 29).

Grallaria quitensis quitensis (nestling)

  • 22.2 g (n = 1, five days old; 8).

Grallaria quitensis quitensis / atuensis

  • Males – range 57–83 g, mean 66 g (n = 19; 19).
  • Females – range 60–70 g, mean 64.7 g (n = 6; 19).

Grallaria quitensis atuensis (adults)

  • Males – 58.2 g, 60 g, 62 g, 69 g, 59 g, 63 g, 64 g, 60 g, 57 g, 66.5 g, 60 g (n = 11; 8).
  • Females – 63 g, 62.5 g, 60.0 g, 62.5 g, 58 g (n = 5; 8).​​​​​​​​​​​​​​​​​​​

Recommended Citation

Greeney, H. F. and A. J. Spencer (2023). Tawny Antpitta (Grallaria quitensis), version 2.0. In Birds of the World (N. D. Sly, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.tawant1.02