_Seasonality of breeding in tropical birds._--Possibly Bornean birds breed mostly in the "driest" part of the year. If so, this is in contrast with the time of breeding of birds of other tropical areas. Moreau (1950) found that in the Congo there was no distinct breeding season for most groups of birds, but that in East Africa there was a double breeding season; the peaks coincided with the two rainy seasons. Lack (1950) found that the Geospizinae of the Galapagos breed only when it rains and that rainfall causes a flurry of nest building and singing. If the rains stop, then the courtship activities stop until the next rains. Miller (1963) found that in birds of a western Andean cloud forest the breeding season was spread over the year and that breeding could not be correlated with rainfall. Obviously more study is required on breeding of birds in Borneo before the timing of the annual cycle can be ascertained. ACCOUNTS OF SPECIES The English names used in this report follow Smythies (1960) where possible. If the bird has not been recorded from Borneo previously, then I have resorted to Delacours and Mayr's "Birds of the Philippines" (1946). The taxonomy is that of Smythies (1960), except where current American or my own opinion differs and where new evidence has warranted a change. The sequence of families is that of Wetmore (1960). Two species listed beyond that had not previously been recorded from the island of Borneo are: Red-footed Booby, _Sula sula_; and Whitehead's Thick-head, _Pachycephala whiteheadi_. Six additional kinds listed beyond had not previously been recorded from North Borneo. They are: Chinese Egret, _Egretta eulophotes_; Knot, _Calidris canutus_; Ground Cuckoo, _Carpococcyx radiceus_; _Stachyris nigriceps hartleyi_; Finch's Bulbul, _Criniger finschii_; and Pale Blue Flycatcher, _Muscicapa unicolor_. _=Sula sula=_ (Linnaeus): Red-footed Booby.--A captive seen in the Tawau police station was said to have been caught when it landed at night on a police launch anchored off Siamil Island in or near May, 1962. The bird was in first-year or second-year plumage, seemed to be tame, and was thriving on a diet of fish. Identification was made by Alexander Wetmore from a photographic print. This is the first seemingly substantiated record of the species from Borneo, although it probably occurs there regularly. The species breeds on Bankoran Island and on Tubbataha Reef in the Sulu Sea (Smythies, 1960:113). _=Fregata ariel=_ (G. R. Gray): Lesser Frigatebird.--This conspicuous bird on the waters around Tawau is occasionally seen in Cowie Harbor but more often along the coast outside the Harbor. On September 20 an estimated 300-500 birds circled over the shore northeast of Tawau. _=Ardea sumatrana sumatrana=_ Raffles: Dusky-gray Heron.--_Specimens_, 2. Karindingen Island: [Male] testis 12 x 23 mm., November 24, 1962, MCT 3308; [Male], November 24, 1962, MCT 3309.