Little known Oriental bird: Chestnut-headed Partridgeby Colin M. Poole, from OBC Bulletin 30, November 1999. Introduction
Discovery Chestnut-headed Partridge was discovered in December 1927 when eight or nine specimens were collected from the Cambodian mountain of Bokor by P. Jabouille and Willoughby Prescott Lowe, members of the Fourth Franco-British Expedition to Indochina (1-4). It was described the following year by Delacour and Jabouille (2). Bokor was a French colonial hill station situated on a plateau at 1,000 m at the southern end of a mountain range known as the Cardamom, Elephant or Kravanh Mountains, stretching 330 km north-west to the Thai border, and this was the first-ever ornithological expedition to the area. At the time, Delacour described both the slopes and the plateau as being 'unspoiled', the slopes were covered with tall damp forest, whilst the summit plateau was 'very peculiar, the trees being rather low and stunted, with an abundance of orchids and other epiphytes' (3). It was in the latter area, on the plateau, that Chestnut-headed Partridge was collected. In 1928, Delacour and Jabouille described Chestnut-headed Partridge as 'a very distinct species' (2) and closer to Red-breasted Partridge A. hyperythra of Borneo than any of its continental congeners (1,3). However, in November 1930, Riley described a new species of partridge, A. diversa, on the basis of a single specimen collected in January 1930 by Dr H. M. Smith from semi-evergreen forest at 300 m at Khao Sabap (also known as Namtok Phliu National Park), Chanthaburi, Thailand (5) – the opposite end of the Cardamom mountain range. At the time, Riley had no specimens of Chestnut-headed Partridge available for comparison and his specimen did not agree with the published description, although he notes it as 'evidently closely allied' (5). Smith, on seeing the plate of Chestnut-headed Partridge published by Delacour and Jabouille in 1931 (p. 50) (6), later retracted A. diversa as a separate species, and in 1938 he described the two forms as subspecies, A. c. cambodiana and A. c. diversa. 7 This is their current taxonomic position, although there is still considerable debate over this view (8,9,10).
Status Since the time of these early collectors there have been very few records of either form. Following his first expedition, Smith returned to Khao Sabap in November 1933 and collected a further four specimens of diversa (7). The subspecies was then unrecorded until March 1966 when B. F. King collected two specimens from hill evergreen forest at 1,129 m altitude on Khao Soi Dao Tai (the more southerly, and the higher, of the two Soi Dao peaks) (P. D. Round in litt.). Although listed by Collar et al. as 'probably common' in Khao Soi Dao, with 'several recent records' (8), I have only been able to trace two records in the wild since. The first is of a single bird seen by R. Harwood in May 1994. (11) The second is of two birds recorded by N. Dymond in February 1998 in montane evergreen forest, at approximately 1,400 m (N. Dymond in litt.). It has seemingly been unrecorded from Khao Sabap since Smith's last expedition of 1933, and there are no other records from Thailand. However, in 1988 at least two birds were recorded and photographed by Uthai Treesucon in captivity at the Pong Namron Captive Breeding Centre of the Wildlife Conservation Division, which is situated at the foot of Khao Soi Dao (p. 50) (P. D. Round in litt.). In 1995, McGowan et al. estimated the population of A. c. diversa to be 100-1,000 and that the 'wild population could be in the low hundreds', whilst that of cambodiana was estimated at more than 100 (9). However, little indication is given as to how, and from what evidence, these figures were derived, and they are therefore best treated with caution. The situation for cambodiana is even less well-known. Following the collection of the original specimens, Bokor was visited in 1935 and 1936 by P. Engelbach, who was resident in the nearby town of Kampot. He found it to be 'relativement trés commune' (relatively very common) between 400–1,000 m and, somewhat surprisingly, recorded it as being easier to approach than other partridge species, often venturing out into open areas. On 14th June one year he saw a pair with an unrecorded number of young chicks (12). This behaviour pattern, unusual for any Arborophila species, has not been reported before or since for either form. However, the fact that in 1927 at least eight birds were collected in two days may indicate that it was, at least then, relatively easy to find. The assertion of Thomas in 1964, that the species was 'common and conspicuous in the Elephant chain' (13), is presumably based on Engelbach, as he cites no personal records and there appear to be no other records since 1936, or from any other locality than Bokor, until the bird I was shown in January 1998. Plumage Flank feathers black with white triangular centres. Belly through to vent pale brown/buff, white undertail. Scapulars and coverts pale brown, those towards the outer-wing being darker and mottled black and those closer to the inner-wing being strikingly pale with black sub-terminal marks and chestnut tips. Secondaries mid-brown, mottled black. Primaries black. Eye black. Bill black. Legs pink. |
