Plumages, Molts, and Structure

Natal Down

Undescribed.

Juvenile

This plumage has only been described for subspecies vanderbilti, which is similar to that of the adult female but with a brighter yellow rump and uppertail coverts, and an indistinct pale gray-brown collar. No yellow on the breast (1 Clement, P., A. Harris, and J. Davis (1993). Finches and Sparrows: An Identification Guide. Christopher Helm, London, UK. Close ).

Rather at variance with this, Ottaviani (2 Ottaviani, M. (2018). Is the subspecies of Mountain Serin Chrysocorythus estherae from Lore Lindu National Park, northern Central Sulawesi province, Indonesia, an undescribed taxon? BirdingASIA 30:54–59. Close ) described the plumage of juveniles in Lore Lindu National Park as “unknown but the plumage of the young female suggests that it is brown heavily spotted with cream above and white heavily streaked with blackish below”.

Immature

Ottaviani (2 Ottaviani, M. (2018). Is the subspecies of Mountain Serin Chrysocorythus estherae from Lore Lindu National Park, northern Central Sulawesi province, Indonesia, an undescribed taxon? BirdingASIA 30:54–59. Close ) described the immature plumages of birds in Central Sulawesi in more detail, but given this undescribed taxon’s orange-red not yellow color in adults, some elements of the immature plumage seem likely to differ from other subspecies also:

Female. Resembles the adult female but the head and upperparts are paler, the underpart striations are darker, and the markings on the tail and wings are yellow, not yellow-orange (2 Ottaviani, M. (2018). Is the subspecies of Mountain Serin Chrysocorythus estherae from Lore Lindu National Park, northern Central Sulawesi province, Indonesia, an undescribed taxon? BirdingASIA 30:54–59. Close ).

Male. Said to resemble the adult male, but the orange-red color on the forecrown is replaced by yellow (like other subspecies) and is much reduced (2 Ottaviani, M. (2018). Is the subspecies of Mountain Serin Chrysocorythus estherae from Lore Lindu National Park, northern Central Sulawesi province, Indonesia, an undescribed taxon? BirdingASIA 30:54–59. Close ).

Adult

Female. Like the adult male but the yellow parts are paler, with little or no yellow on the forehead and crown, may show white lores and a narrow eye-ring; also yellow on the rump and yellow tips to the wing coverts are paler or duller, the breast mostly buffish white with a slight tinge of yellow at the sides, and the streaks on the underparts slightly more extensive.

Male. The nominate subspecies has the forehead, lower sides of the crown, and submoustachial area yellow (can appear spotted, with dark feather bases showing), whilst the rest of the crown, nape, and ear coverts are gray-brown. Mantle, back, and scapulars olive-brown, tinged gray, whilst the rump and uppertail coverts are a vibrant golden-yellow (the uppertail coverts may show broad dark centers). Tail blackish brown. Upperwing coverts blackish brown, with pale yellow tips to the median and greater coverts (forming double wingbars); alula, primary coverts, and remiges blackish brown, in fresh plumage the secondaries are thinly edged pale yellowish white, and the tertials edged pale yellow on their outer webs. Chin to lower throat brownish, breast pale buffish white or yellow, heavily spotted or streaked blackish brown, with the markings continuing onto the whitish flanks, and the belly to undertail coverts unstreaked white.

Information needed.

Bill

Short, deep-based and fairly stubby, with a strongly arched culmen. Dark brown or olive-brown on maxilla, paler brown on the mandible (1 Clement, P., A. Harris, and J. Davis (1993). Finches and Sparrows: An Identification Guide. Christopher Helm, London, UK. Close ). Populations in Central Sulawesi are said to have an all-black bill (2 Ottaviani, M. (2018). Is the subspecies of Mountain Serin Chrysocorythus estherae from Lore Lindu National Park, northern Central Sulawesi province, Indonesia, an undescribed taxon? BirdingASIA 30:54–59. Close ).

Iris and Facial Skin

Iris is dark brown to blackish (1 Clement, P., A. Harris, and J. Davis (1993). Finches and Sparrows: An Identification Guide. Christopher Helm, London, UK. Close ).

Tarsi and Toes

Brown or dark brown (1 Clement, P., A. Harris, and J. Davis (1993). Finches and Sparrows: An Identification Guide. Christopher Helm, London, UK. Close ).

Linear Measurements

Overall length 11–12 cm.

Linear measurements, of the nominate subspecies, in mm, from Schuchmann and Wolters (3 Schuchmann, K.-L., and H. E. Wolters (1982). A new subspecies of Serinus estherae (Carduelidae) from Sulawesi. Bulletin of the British Ornithologists’ Club 102(1):12–14. Close ):

Mass

No data (4 Dunning, J. B., Jr. (2008). CRC Handbook of Avian Body Masses. Second edition. CRC Press, Boca Raton, FL, USA. Close ).