Ferruginous Partridge Caloperdix oculeus Scientific name definitions

Ferruginous Partridge is distinctive with a bright rufous head and underparts, black mantle and flanks with white scallops, and olive-brown wings with large black spots.

Ferruginous Partridge has 11 primaries (including remicle), curved secondaries, and 14 tail feathers (1 Madge, S., and P. McGowan (2002). Pheasants, Partridges and Grouse, including Buttonquails, Sandgrouse and Allies. Christopher Helm, London, UK. Close ). It is eutaxic (2 Marchant, S., and P. J. Higgins, Editors (1993). Handbook of Australian, New Zealand and Antarctic Birds. Volume 2. Raptors to Lapwings. Oxford University Press, Melbourne, Australia. Close , 3 Bostwick, K. S., and M. J. Brady (2002). Phylogenetic analysis of wing feather taxis in birds: macroevolutionary patterns of genetic drift? Auk 119(4):943–954. Close ). Feathers have a long aftershaft. Down is on apteria only. Sexes are similar in all plumages (but females have 0–1 tarsal spurs compared to 1–2 in males [1 Madge, S., and P. McGowan (2002). Pheasants, Partridges and Grouse, including Buttonquails, Sandgrouse and Allies. Christopher Helm, London, UK. Close ]). The following is based primarily on plumage descriptions of nominate subspecies (see Subspecies) from Madge and McGowan (1 Madge, S., and P. McGowan (2002). Pheasants, Partridges and Grouse, including Buttonquails, Sandgrouse and Allies. Christopher Helm, London, UK. Close ), Treesucon and Limparungpatthanakij (4 Treesucon, U., and W. Limparungpatthanakij (2018). Birds of Thailand. Lynx Edicions, Barcelona, Spain. Close ) and Lim et al. (5 Lim, K. S., Y. D. Li, and K. C. Lim (2020). Birds of Malaysia & Singapore. Princeton Field Guides. Princeton University Press, Princeton and Oxford. Close ) plus examination of Macaulay Library images. See Molts section for molt and plumage terminology.

Natal Down

Natal down is a deep yellowish, darker brown on the upperparts and paler yellowish on the breast. There is a thin dark brown line supercilium and a dark brown crown.

Juvenile (First Basic) Plumage

Juvenile Plumage is short-lived in growing young, and soon replaced by Formative Plumage. Juvenile plumage has chestnut brown wings and back with buffy spots on the feather tips. The underparts are orange-rufous, lighter than in adult plumage.

Formative Plumage

Formative Plumage resembles Definitive Basic, but is duller and paler. Feather edges may be more buffy than white, and some irregular blackish bars or spots may be present on the breast. The rear crown and nape may have some blackish scaling.

Definitive Basic Plumage

The head, breast, and belly are bright rufous. The face is paler buffy-orange, with a faint dusky line behind the eye. The upper back, mantle, breast sides, and flanks are black with narrow white scaling. The rump and uppertail coverts are black with rufous v-shaped bars. The wings are olive-brown with large dark terminal spots on the coverts. The tail is black. The belly is whitish mixed with rufous, and the rear flanks and undertail coverts are a mix of whitish and rufous with black spots or bars.

Molt and plumage terminology follows Humphrey and Parkes (6 Humphrey, P. S., and K. C. Parkes (1959). An approach to the study of molts and plumages. Auk 76(1):1–31. Close ) as modified by Howell et al. (7 Howell, S. N. G., C. Corben, P. Pyle, and D. I. Rogers (2003). The first basic problem: a review of molt and plumage homologies. Condor 105:635–653. Close , 8 Howell, S. N. G., C. Corben, P. Pyle, and D. I. Rogers (2004). The first basic problem revisited: reply to commentaries on Howell et al. (2003). Condor 106:206–210. Close ) and Johnson et al (9 Johnson, E. I., Wolfe, J. D., Ryder, T. B. and P. Pyle (2011). Modifications to a molt-based ageing system proposed by Wolfe et al. (2010). J. Field Ornithol. 82(4):422–424. Close ). There is little publishing information on molt for Ferruginous Partridge, but based on Macaulay Library images and comparison to related phasianids, it likely exhibits a Complex Basic Strategy, including complete prebasic molts and an incomplete or complete preformative molt, but no prealternate molts.

Prejuvenile Molt

There is no published information available on Prejuvenile Molt for this species. Replacement of natal down with Juvenile Plumage likely begins at a young age, possibly within days of hatching as in related phasianids.

Preformative Molt

Preformative Molt is complete, and males assume Formative Plumage in the first year.

Definitive Prebasic Molt

Definitive Prebasic Molt is complete. The timing varies according to sex, locality and breeding success. Females molt later than males.

Bill

Dark brown.

Iris

Dark brown.

Tarsi and Toes

Yellow. Male has two spurs, while the female has one or no spur (4 Treesucon, U., and W. Limparungpatthanakij (2018). Birds of Thailand. Lynx Edicions, Barcelona, Spain. Close ).

Linear Measurements

Total length 23–27 cm.

Mass

One male 191 g, one female ca. 230 g (10 Wells, D. R. (1999). The Birds of the Thai-Malay Peninsula. Volume 1. Non-passerines. Academic Press, London, UK. Close ).

Three subspecies recognized (11 Clements, J. F., T. S. Schulenberg, M. J. Iliff, T. A. Fredericks, J. A. Gerbracht, D. Lepage, S. M. Billerman, B. L. Sullivan, and C. L. Wood (2022). The eBird/Clements checklist of Birds of the World: v2022. Cornell Laboratory of Ornithology, Ithaca, NY, USA. Close ).

Found in several disjunct populations on mainland southeast Asia and the Greater Sundas. On mainland southeast Asia, found from southeastern Myanmar and southwestern Thailand south through Peninsular Malaysia (to Pahang). Also found on Sumatra and north-central and northeast Borneo.

Found in evergreen and semi-evergreen forest, in a variety of situations according to locality, including dry forest in mountains, and both primary and secondary forest in sandy valleys; also in secondary scrub, which is the main habitat in Sumatra, and bamboo-dominated second growth. Occurs from lowlands up to ca. 1200 m (10 Wells, D. R. (1999). The Birds of the Thai-Malay Peninsula. Volume 1. Non-passerines. Academic Press, London, UK. Close ).

No information available, presumably resident.

Seeds, grasses, berries, fallen figs and insects reported. Forages alone or in pairs, with reports of small groups apparently unconfirmed (10 Wells, D. R. (1999). The Birds of the Thai-Malay Peninsula. Volume 1. Non-passerines. Academic Press, London, UK. Close ).

Song a series of gradually accelerating and ascending whistles, subsequently bursting into several harsher notes, e.g. “wee-we-we-wi-wiwiwiwiwiwi.. kee-crrow..kee-crrow..kee-crrow” . Calling reported in January, May, June, and August in Peninsular Malaysia (10 Wells, D. R. (1999). The Birds of the Thai-Malay Peninsula. Volume 1. Non-passerines. Academic Press, London, UK. Close ).

Half-grown young in mid-September on the Malay Peninsula (10 Wells, D. R. (1999). The Birds of the Thai-Malay Peninsula. Volume 1. Non-passerines. Academic Press, London, UK. Close ). On Borneo, in Sarawak, locals report a domed nest with an entrance hole and ca. 8–10 pure white eggs in December–January. Two downy young collected in Padang Highlands, West Sumatra, but no further details. Incubation 18–20 days in captivity.

Not globally threatened. Currently considered Near Threatened. Known from total of 32 localities throughout range prior to mid 1990s (13 McGowan, P., M. Gillman, and M. Dodd (1998). Assessing the status of poorly known species: lessons from partridges and pheasants of Southeast Asia. Biological Conservation 83(1):1–7. Close ). Widespread in Sumatra, but apparently rare, with comparatively few recent records; very scarce in Thailand; no information from Malaysia. Believed declining as consequence of habitat destruction throughout range; overhunted in Thailand. Known from several protected areas in all three countries, including Kaeng Krachen and Thaleban National Parks in Thailand, Taman Negara National Park in Malaysia, and Gunung Leuser and Kerinci Seblat National Parks on Sumatra, although it seems to be completely unprotected on Borneo (14 Mann, C. F. (2008). The Birds of Borneo: An Annotated Checklist. B.O.U. Checklist 23. British Ornithologists’ Union, and British Ornithologists’ Club, Peterborough. Close ), where in Kalimantan it is known from just two localities (15 Brickle, N. W., J. A. Eaton, and F. E. Rheindt (2010). A rapid bird survey of the Menyapa mountains, East Kalimantan, Indonesia. Forktail 26:31–41. Close ). Recent records from 100 m at Sako, West Sumatra, at ca. 800 m in West Sumatra, in dry forest in the lowlands of Way Kambas, southeastern Sumatra, and one at 1000 m at Gunung Leuser National Park. Not protected by Indonesian law. CITES III in Malaysia.

Chuenchom Hansasuta received a Doctor of Dental Surgery from Chulalongkorn University. During her long and distinguished career in dentistry, she studied and practiced in places such as Thammasat University (Thailand), State University of New York at Buffalo (USA), and University of Connecticut Health Center (USA) and retired in 2020. Chuenchom always had an intense curiosity for birds that over time, evolved into an acute interest in plumages. She has long been active in education and volunteering, becoming chairwoman of The Flyway Foundation and actively engaging and educating the public in the study of birds and their plumages.