This species was common in the cocoa and surrounding secondary forest at Quoin Hill, but I saw it only once in the moss forest on the mountains near Tenom.
No specimen taken showed characters of or tendencies toward C. malabaricus suavis. Perhaps the zone of intergradation on the east coast is farther south than Darvel Bay, where it was placed by Smythies (1960:390).
S. D. Ripley (in Peters et al., 1964:72) considered C. stricklandi to be specifically distinct from C. malabaricus, and his opinion is accepted here.
Enicurus leschenaulti borneensis Sharpe: White-crowned Forktail. Specimens, 4: 12 mi. N Kalabakan: ♀ imm., October 21, 1962, MCT 3112; ♀ largest ovum 2 mm., October 27, 1962, MCT 3167; ♂, November 1, 1962, MCT 3195. Gum-Gum: ♀, September 24, 1963, ADG 282.
I saw this species only once in life, along a small, wet-weather stream. The specimens, however, were all netted in primary forest, some distance away from any stream.
Judging from measurements, these specimens are E. l. borneensis, although one would expect to find only E. l. frontalis at elevations of 600 feet. The specimen taken by Garcia at Gum-Gum was not identified to subspecies.
Enicurus ruficapillus Temminck: Chestnut-naped Forktail.—Specimens, 3: 12 mi. N Kalabakan: ♂, October 21, 1962, MCT 3113; ♂, November 4, 1962, MCT 3207; ♂, November 8, 1962, MCT 3231.
This bird was common along the upper Apas River at Quoin Hill. All specimens were taken in nets stretched across streams.
Zoothera interpres interpres (Temminck): Chestnut-headed Ground Thrush.—Specimens, 9: 12 mi. N Kalabakan: ♀, October 28, 1962, MCT 3171; ♀, October 24, 1962, MCT 3138. Kalabakan: ♀, November 17, 1962, MCT 3300. Cocoa Research Station: ♀ imm., June 10, 1963, ADG 120; ♂, June 12, 1963, ADG 130; ♀ imm., June 15, 1963, ADG 141. Oil Palm Research Station: ♂, August 15, 1963, ADG 233; ♂, August 9, 1963, ADG 217; ♂, August 27, 1963, ADG 261.
The many specimens of this species taken indicate the effectiveness of mist nets in collecting birds in tropical forest. Although Smythies (1960:398) considered this bird to be rare in Borneo, I think that it is merely shy and retiring. We never saw the species in the field and the specimens were all netted. The habitat was in primary forest, except for that of MCT 3300, which was taken in dense secondary forest. The two birds from 12 miles north of Kalabakan were taken in a net stretched across a surveyor's transect. The net was set on a hilltop and the birds hit it approximately three feet above the ground. Two of the specimens from the Cocoa Research Station are in juvenal plumage, indicating that this species probably breeds in the area.
Cettia whiteheadi (Sharpe): Short-tailed Bush Warbler.—Specimen, 1: 5.5 mi. SW Tenom: ♂ testis 3 × 2 mm., December 21, 1962, MCT 3488.
The specimen was netted in the moss forest, in fairly heavy secondary undergrowth.
Prinia flaviventris (Delessert): Yellow-bellied Wren-Warbler.—On September 2, 1962, I saw several of these wren-warblers in a grassy area near the golf course at Tawau.