This was an abundant bird on the Jesselton-Tuaran road but was not seen at any of the other collecting stations in North Borneo.
Collocalia fuciphaga natunae Stresemann: Thunberg Swiftlet.—Specimens, 3: Cocoa Research Station: ♀ largest ovum 7 mm., oviduct enlarged, 13.1 gm., June 30, 1962, MCT 2570; ♀ ovary small, September 8, 1962, MCT 2887. 5.5 mi. SW Tenom: ♀, December 20, 1962, MCT 3485.
This swiftlet was seen every day while we were at the Cocoa Research Station and was common also in the mountains around Tenom, where it flew in and out of the fog over our camp.
Collocalia esculenta ssp.: White-bellied Swiftlet.—Specimens, 7: Cocoa Research Station: ♂, 5.5 gm., July 4, 1962, MCT 2591; ♂, 6.2 gm., July 5, 1962, MCT 2594; ♂, 6.2 gm., July 1, 1962, MCT 2574; ♀, 6.0 gm., July 4, 1962, MCT 2589; ♀, 5.7 gm., July 4, 1962, MCT 2590. 12 mi. N Kalabakan: ♂ testis 4 × 2 mm., November 10, 1962, MCT 3236; ♂, November 10, 1962, MCT 3237.
This was the most abundant of all the swifts at the Cocoa Research Station and in the Kalabakan area and was seen also at Semporna on August 16, 1962, in a small coral cave near the District Officer's house. This cave was 10 feet high at most, but averaged five to six feet. It harbored about 1,000 birds, most of them nesting back in the dimly lit zone but one small group of 50 nested in the entrance in bright light. The adults were still feeding young, although the latter could fly strongly.
Chaetura leucopygialis (Blyth): White-rumped Spine-tailed Swift.—Specimens, 12: Cocoa Research Station: ♀ well-developed brood patch, June 28, 1962, MCT 2565; ♀, 12.9 gm., June 30, 1962, MCT 2567; ♀, June 30, 1962, heavy molt on body, head, wing, tail, MCT 2568; ♀, 14.5 gm., June 30, 1962, MCT 2569; ♀, 13.0 gm., June 30, 1962, MCT 2571; ♀, 13.0 gm., July 1, 1962, MCT 2572; ♂ testis 4 × 2 mm., 12.3 gm., July 1, 1962, MCT 2575; ♂ testis 2 × 1 mm., 14.9 gm., July 2, 1962, MCT 2576; ♀, 15.4 gm., July 5, 1962, MCT 2595; ♂ testis 2 × 1 mm., 15.4 gm., wing molt, July 5, 1962, MCT 2596; ♂ testis 2 × 1 mm., 11.9 gm., July 6, 1962, MCT 2598; ♀, 13.0 gm., July 6, 1962, MCT 2599.
This species was common around the Cocoa Research Station but was not seen elsewhere. There is some variation in color within the populations.
Hemiprocne comata comata (Temminck): White-whiskered Tree Swift.—Specimens, 3: Cocoa Research Station: ♂ testis 2 × 1 mm., 17.0 gm., July 28, 1962, MCT 2675; sex?, young in juvenal plumage, MCT 2812; ♂, April 28, 1963, ADG 76.
At the Cocoa Research Station this common bird usually was seen sitting on a dead branch of a shade tree in the cocoa whence it would dart out after insects. It rarely perched higher than 12 feet. Occasionally it was seen in a clearing in the primary forest.