Plumages, Molts, and Structure

The White-throated Antpitta, like other members of the Grallariidae, have 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; 5 Ridgway, R. (1911). The birds of North and Middle America: A descriptive catalogue of the higher groups, genera, species, and subspecies of birds known to occur in North America, from the Arctic Lands to the Isthmus of Panama, the West Indies and other Islands of the Caribbean Sea, and the Galapagos Archipelago. Part V. Bulletin of the United States National Museum 50. Close , 6 Johnson, E. I., and J. D. Wolfe (2018). Molt in Neotropical Birds: Life History and Aging Criteria. Studies in Avian Biology 51. CRC Press, Boca Raton, FL, USA. Close ). The following plumage descriptions are primarily from Chapman (7 Chapman, F. M. (1923). Descriptions of proposed new Formicariidae and Dendrocolaptidae. American Museum Novitates 86:1–20. Close ), Ridgely and Tudor (8 Ridgely, R. S., and G. Tudor (2009). Field Guide to the Songbirds of South America: The Passerines. University of Texas Press, Austin, TX, USA. Close ), Krabbe and Schulenberg (9 Krabbe, N., and T. S. Schulenberg (2003). Family Formicariidae (ground-antbirds). In Handbook of the Birds of the World. Volume 8: Broadbills to Tapaculos (J. del Hoyo, A. Elliott, and D. A. Christie, Editors). Lynx Edicions, Barcelona, Spain. pp. 682–731. Close ), and Greeney (4 Greeney, H. F. (2018). Antpittas and Gnateaters. Christopher Helm, London, UK. Close ). Plumages are labeled, in parentheses, with the categorical, age-based terminology employed for antpittas by Greeney (4 Greeney, H. F. (2018). Antpittas and Gnateaters. Christopher Helm, London, UK. Close ). See also Molts for molt and plumage terminology. Sexes are similar in all plumages.

Natal Down

Not described.

Post-Natal Down (Nestling — Fledgling)

Not described.

First Basic (Juvenile) Plumage

Not described.

First Formative (Subadult) Plumage

In his description of the type, Chapman (7 Chapman, F. M. (1923). Descriptions of proposed new Formicariidae and Dendrocolaptidae. American Museum Novitates 86:1–20. Close ) stated that "immature males" are similar to adult males but have the underparts washed brownish and the flanks and sides tinged with the same coloration as the back. He did not provide his basis for this description of immature plumage, but presumably this description refers to subadults, as he does not mention any other aspects of immature plumage typical of juvenile Grallaria, such as patterned upperwing coverts or patches of barred plumage (4 Greeney, H. F. (2018). Antpittas and Gnateaters. Christopher Helm, London, UK. Close ). Greeney (4 Greeney, H. F. (2018). Antpittas and Gnateaters. Christopher Helm, London, UK. Close ) provided a more complete description of an individual in subadult plumage. The crown, nape, and ear-coverts are bright chestnut-rufous as in adults, but the forecrown has dusky feathers mixed in, giving it a "disheveled" appearance. The lores and anterior malar region (base of bill and below eye) are dusky-white or blackish (overall darker and not as "clean"as in adults). The back is olivaceous-brown as in adult plumage, but the lower back, rump, and uppertail coverts were not described. The underside of the tail and wings are dark, slightly reddish-brown and, as in adults, the leading edges of the primaries are paler tawny-brown. The upperwing coverts are slightly darker (duskier) than the flight feathers; they bear a fairly broad, darker blackish subterminal band and are thinly tipped buffy-chestnut. The throat, as far back as the lower posterior edge of the ear-coverts, is white, irregularly washed with small areas of gray, unlike the clean, bright white throats of adults. The contrasting line between the throat and the underparts is somewhat blurred, rather than cleanly delimited. The remaining underparts appear similar to those of adults, but the olive wash on the flanks is more extensive and there are scattered patches of olive or rusty-olive feathers on the belly and breast.

Definitive Basic (Adult) Plumage

The crown, nape, and ear coverts are bright chestnut-rufous, somewhat deeper or darker rufous on the ear coverts and forecrown, and becoming brighter posteriorly, especially on nape, where it has a somewhat olivaceous tinge as it grades into the coloration of the upper back. The lores and anterior malar is grayish, dusky-white, or sometimes white slightly peppered with black. The upperparts are olivaceous-brown, except for the uppertail coverts and tail, which are more reddish-brown. The wings are similar to the tail and have the primaries edged paler tawny-brown on the leading edge, especially basally. The upperwing coverts are brownish-olive, similar to the back. The throat, rearward to the lower posterior edge of the ear coverts, is snowy white, contrasting with the pale gray to mid-gray breast and belly. The central breast and especially the belly is whiter, becoming darker gray laterally, and washed olive on the flanks. The undertail coverts are pale gray washed olive-brown.

Molt and plumage terminology follows Humphrey and Parkes (10 Humphrey, P. S., and K. C. Parkes (1959). An approach to the study of molts and plumages. Auk 76(1):1–31. Close ) as revised by Howell et al. (11 Howell, S. N. G., C. Corben, P. Pyle, and D. I. Rogers (2003). The first basic problem: A review of molt and plumage homologies. The Condor 105:635–653. Close ). No specific information has been published for the White-throated Antpitta, but it likely follows a similar molt strategy to the Variegated Antpitta (Grallaria varia), as described by Johnson and Wolfe (6 Johnson, E. I., and J. D. Wolfe (2018). Molt in Neotropical Birds: Life History and Aging Criteria. Studies in Avian Biology 51. CRC Press, Boca Raton, FL, USA. Close ). The White-throated Antpitta likely exhibits a Complex Basic Strategy (cf. 11 Howell, S. N. G., C. Corben, P. Pyle, and D. I. Rogers (2003). The first basic problem: A review of molt and plumage homologies. The Condor 105:635–653. Close , 12 Howell, S. N. G. (2010). Peterson Reference Guide to Molt in North American Birds. Houghton Mifflin Harcourt, Boston, MA, USA. Close ), including incomplete prebasic molts and a partial preformative molt but no prealternate molts (13 Ryder, T. B., and J. D. Wolfe (2009). The current state of knowledge on molt and plumage sequences in selected Neotropical bird families. Ornitología Neotropical 20:1–18. Close , 14 Wolfe, J. D., T. B. Ryder, and P. Pyle (2010). Using molt cycles to categorize the age of tropical birds: An integrative new system. Journal of Field Ornithology 81:186–194. Close , 4 Greeney, H. F. (2018). Antpittas and Gnateaters. Christopher Helm, London, UK. Close , 6 Johnson, E. I., and J. D. Wolfe (2018). Molt in Neotropical Birds: Life History and Aging Criteria. Studies in Avian Biology 51. CRC Press, Boca Raton, FL, USA. Close ).

Bill and Gape

Maxilla blackish gray, mandible blue-gray in adults. In subadults, the maxilla is blackish gray, slightly paler distally and on the tomia, with the latter becoming more yellow-orange basally onto the minimally inflated rictus, and the mandible is blue-gray with the tomia of the basal third and the rictus as on the maxilla (4 Greeney, H. F. (2018). Antpittas and Gnateaters. Christopher Helm, London, UK. Close ). Bill color is not described in fledglings or juveniles.

Iris and Facial Skin

Brown in adults and dark brown in subadults. The bare skin around the eye is pale bluish-white and forms an eye-ring that is wider behind the eye. Neither iris color or the color of the bare facial skin is described for fledglings or juveniles.

Tarsi and Toes

Blue-gray in both adults and subadults. Not described in fledglings or juveniles.

Very few published data. Measurements referring to individuals of putative subspecies cinereiventris (see Systematics: Subspecies) are indicated, where appropriate.

General Size

• Total Length: 18.5–20.3 cm (15 Meyer de Schauensee, R. (1970). A Guide to Birds of South America. Academy of Natural Sciences, Philadelphia, Pennsylvania, USA. Close , 16 de la Peña, M. R. (1988). Guía de Aves Argentinas. Volume 5. Passeriformes. Dendrocolaptidae, Furnariidae, Formicariidae, Tyrannidae. Literature of Latin America, Buenos Aires, Argentina. Close , 17 Narosky, T., and D. Yzurieta. (1989). Birds of Argentina and Uruguay: a field guide. Zagier and Urruty Publications, Buenos Aires, Argentina. Close , 3 Ridgely, R. S., and G. Tudor (1994). The Birds of South America. Volume 2. University of Texas Press, Austin, Texas, USA. Close , 18 de la Peña, M. R., and M. Rumboll (1998). Collins Illustrated Checklist: Birds of Southern South America and Antarctica. Harper Collins, London. Close , 9 Krabbe, N., and T. S. Schulenberg (2003). Family Formicariidae (ground-antbirds). In Handbook of the Birds of the World. Volume 8: Broadbills to Tapaculos (J. del Hoyo, A. Elliott, and D. A. Christie, Editors). Lynx Edicions, Barcelona, Spain. pp. 682–731. Close ).

Linear Measurements

Male

• Wing length – 101 mm (n = 1, holotype; 7 Chapman, F. M. (1923). Descriptions of proposed new Formicariidae and Dendrocolaptidae. American Museum Novitates 86:1–20. Close ); 106 mm, 107 mm, 101.5 mm, 103 mm (n = 4; 19 Bond, J., and R. Meyer de Schauensee (1942). The birds of Bolivia. Part 1. Proceedings of the Academy of Natural Sciences of Philadelphia 94:307–391. Close ).
• Bill length [total(?) culmen] – 28 mm (n = 1, holotype; 7 Chapman, F. M. (1923). Descriptions of proposed new Formicariidae and Dendrocolaptidae. American Museum Novitates 86:1–20. Close ).
• Bill length [from nares] – 15.1 mm (n = 1; 4 Greeney, H. F. (2018). Antpittas and Gnateaters. Christopher Helm, London, UK. Close ).
• Tail length – 65 mm (n = 1, holotype; 7 Chapman, F. M. (1923). Descriptions of proposed new Formicariidae and Dendrocolaptidae. American Museum Novitates 86:1–20. Close ).
• Tarsus length – 55 mm (n = 1, holotype; 7 Chapman, F. M. (1923). Descriptions of proposed new Formicariidae and Dendrocolaptidae. American Museum Novitates 86:1–20. Close ); 53.2 mm (n = 1; 4 Greeney, H. F. (2018). Antpittas and Gnateaters. Christopher Helm, London, UK. Close ).

Female

• Wing length – 99.5 mm, 100.5 mm (n = 2; 20 Bond, J. (1950). Notes on Peruvian Formicariidae. Proceedings of the Academy of Natural Sciences of Philadelphia 102:1–26. Close ); 109 mm (n = 1, holotype of cinereiventris; 21 Olrog, C. C., and F. Contino (1970). Una nueva subespecie de Grallaria albigula Chapman (Aves, Formicariidae). Neotrópica 16:51–52. Close ).
• Bill length [exposed culmen] – 22 mm (n = 1, holotype of cinereiventris; 21 Olrog, C. C., and F. Contino (1970). Una nueva subespecie de Grallaria albigula Chapman (Aves, Formicariidae). Neotrópica 16:51–52. Close ).
• Bill length [from nares] – 15.2 mm (n = 1; 4 Greeney, H. F. (2018). Antpittas and Gnateaters. Christopher Helm, London, UK. Close ).
• Tail length – "86 mm" [= 68 mm?] (n = 1, holotype of cinereiventris; 21 Olrog, C. C., and F. Contino (1970). Una nueva subespecie de Grallaria albigula Chapman (Aves, Formicariidae). Neotrópica 16:51–52. Close ).
• Tarsus length – 51.3 mm (n = 1; 4 Greeney, H. F. (2018). Antpittas and Gnateaters. Christopher Helm, London, UK. Close ); 60 mm (n = 1, holotype of cinereiventris; 21 Olrog, C. C., and F. Contino (1970). Una nueva subespecie de Grallaria albigula Chapman (Aves, Formicariidae). Neotrópica 16:51–52. Close ).

Mass

Male

• 84 g, 92 g, 86 g, (n = 3; 4 Greeney, H. F. (2018). Antpittas and Gnateaters. Christopher Helm, London, UK. Close ; LSUMZ data previously reported by 9 Krabbe, N., and T. S. Schulenberg (2003). Family Formicariidae (ground-antbirds). In Handbook of the Birds of the World. Volume 8: Broadbills to Tapaculos (J. del Hoyo, A. Elliott, and D. A. Christie, Editors). Lynx Edicions, Barcelona, Spain. pp. 682–731. Close ); 86.5 g (n = 1; 4 Greeney, H. F. (2018). Antpittas and Gnateaters. Christopher Helm, London, UK. Close ); 88 g (n = 1, cinereiventris; 4 Greeney, H. F. (2018). Antpittas and Gnateaters. Christopher Helm, London, UK. Close ),

Female

• 87 g, 90 g (n = 2; 4 Greeney, H. F. (2018). Antpittas and Gnateaters. Christopher Helm, London, UK. Close ; LSUMZ data previously reported by 9 Krabbe, N., and T. S. Schulenberg (2003). Family Formicariidae (ground-antbirds). In Handbook of the Birds of the World. Volume 8: Broadbills to Tapaculos (J. del Hoyo, A. Elliott, and D. A. Christie, Editors). Lynx Edicions, Barcelona, Spain. pp. 682–731. Close ); 116 g (n = 1; 4 Greeney, H. F. (2018). Antpittas and Gnateaters. Christopher Helm, London, UK. Close ); 95 g (n = 1, cinereiventris; 22 Salvador, S. A. (1988). Datos de peso de aves argentinas. El Hornero 13:78–83. Close , 23 Dunning, J. B., Jr. (2008). CRC Handbook of Avian Body Masses. 2nd edition. CRC Press, Boca Raton, FL, USA. Close ).