Quoin Hill.—At this locality I recognized five habitat types as follows:

Primary forest.—We were fortunate to be able to work at Quoin Hill because it had been opened to cultivation (of Cocoa, Theobroma cacao) for only a few years. Thus the primary forest here started at the edge of the Cocoa Research Station. This was in marked contrast to areas on the west coast, where one would need to travel many miles inland to find virgin forest. The forest at Quoin Hill was typical tropical rain-forest, composed mostly of dipterocarps (Dipterocarpaceae). These comprise an essentially Indo-Malayan family, members of which are so conspicuous that we commonly referred to it as Evergreen Dipterocarp Forest. The lowland forests of Borneo are composed of approximately 3,000 species of trees (Browne, 1955). At Quoin Hill, as in most of the tropical rain-forest of Borneo, the forest canopy is stratified in three layers, a distinct and easily recognizable top story and less easily separable middle and lower stories. The top canopy is composed of foliage of giant trees that may tower to heights of 200 feet and have trunks three to seven feet in diameter. The trunk is usually unbranched for 50 to 100 feet and the whole tree is supported by buttresses jutting out from the main trunk. Some of the most important plants in the tropical rain-forest are the strangler figs (Ficus sp.). These plants, when in fruit, draw birds in large flocks to feed upon them. Such figs were common about the edges of the research station and some birds taken from these trees were never taken elsewhere. The birds seemed to wait for a certain degree of ripeness of fruits; on one day the figs were unmolested and the next day the trees would be swarming with birds. Strangler fig trees reach tremendous size and help form the upper forest canopy.

The middle and lower forest canopies are not easily separable and I shall speak of them together. The trees forming these varied from 10 to 60 feet in height. The ground surface beneath the trees was usually bare except for leaf litter and dead branches. Sunlight penetrates only where the big trees have been removed or where the larger trees are otherwise widely spaced. At Quoin Hill the large trees of species affording lumber of commercial quality had been taken out, modifying somewhat the character of the forest. Such forest actually contained many of the animals characteristic of primary forest, and I refer to it as badly disturbed primary forest.

Secondary forest.—In some of the areas adjoining the research station, roads had been bulldozed for future expansion and trees had been cut. These areas were starting to grow dense stands of grass and shrubs and will be jungle in a few years unless cut back. Most of the trees in this area are saplings with some trees as large as a foot in diameter.

Fluviatile waters.—There are numerous small streams in the Quoin Hill area, the largest being the Balung River and Apas River. Little work was done along these streams and only the thrushes of the genus Enicurus and some kingfishers seemed to be confined to them.

Cocoa plantations.—Artificial plantings of cocoa, Theobroma cacao, formed a major habitat type at Quoin Hill, and provided a major source of food for birds. Cocoa planters have found it necessary to provide shade with trees of some other species. In some instances trees from the original primary forest were left standing to provide this shade, but more often exotic trees were planted. Most of the shade trees were of no use to birds save for providing resting places. Trema orientalis was the most important in providing food for birds. Its fruit was used more by the frugivorous species of birds than that of any other tree in the cocoa plantings. Tree Cassava, an exotic, was constantly attended by the nectariniids, or honey creepers.

Although the cocoa plantings did not provide much plant material for bird food, they did apparently nourish a horde of insects, which the birds fed upon. A Drongo-cuckoo, Surniculus lugubris, had 50 caterpillars in its stomach. Healthy cocoa trees were sparsely inhabited by birds but areas that were obviously infested with insects literally swarmed with birds. Dead shade trees in the cocoa plantings also provided food for woodpeckers, with four species being found utilizing these dead trees.

Abaca.—The last of the habitat types that I recognized at Quoin Hill was a small grove of Abaca, Musa textilis, and wild bananas, Musa sp. This habitat type was frequented by spiderhunters (Arachnothera sp.) of the family Nectariniidae.

Kalabakan.—We worked at three localities in this area: 12 miles north of Kalabakan, Brantian Estate, and Kalabakan.

Primary forest.—We were fortunate in being able to work on the very edge of the primary forest 12 miles north of Kalabakan. The composition of the primary forest was much like that at Quoin Hill and will not be discussed further. About a month after we arrived at our forest camp, logging crews moved in and cut the commercial timber near our area. The only immediately noticeable difference in the makeup of the avifauna after destruction of the forest canopy was the appearance of the drongo Dicrurus aeneus. This drongo was seen in areas where the trees had been cut, sitting on limbs and darting out after insects.

Secondary forest.—The area around Kalabakan proper was in secondary forest, which was almost impossible to penetrate. At Kalabakan, Cymbirhynchus macrorhynchus, Cecropsia striolata, and Macronous ptilosus were taken and I did not see them elsewhere. Kalabakan is situated on the Kalabakan River at the upper tidal limit. The Nipa-Mangrove association, not investigated, lies immediately below Kalabakan.

The Brantian Estate area was mostly in secondary forest and was situated on the Brantian River. There were some fairly large areas of grass with water buffalo wallows in them. These grassy areas were favorite haunts of the Painted Quail, Coturnix chinensis.

Tenom.—The first locality that we investigated was 5.5 miles southwest of Tenom, approximately 4,000 feet elevation, in moss forest. A few days were spent collecting in the area of Tenom itself.

Moss forest.—The lower altitudinal limit of the moss forest was about 3,600 feet. The trees on top of the mountain were mostly oaks (Quercus) and were festooned with ferns, orchids, and other epiphytes. The area had been used as a triangulation station by a survey team and a small area on top of the mountain had been cleared earlier. At the time of our visit this small area had grown to secondary vegetation, mostly Pandanus. The oaks in the primary forest surrounding this disturbed area were generally about 30 to 50 feet high and there was little undergrowth in virgin stands. This area was usually swathed in fog from three o'clock in the afternoon until eleven o'clock the next morning. One morning of our fourteen there was clear.

Paddy.—The area visited at Tenom itself consisted mostly of old paddy grown to grass and scrub. Forest did occur but was of secondary nature in the immediate vicinity of Tenom.

Siamil Island.—This island is about one mile in circumference and the highest point is about 300 feet above sea level. The island has high bluffs on three sides but slopes gently to the sea on the other. There were patches of forest left on the island, one on the north side and one on the south. The sheer bluffs on the east side of the island were covered with Pandanus sp. The undergrowth of the north forest had been cut, leaving extensive bare areas. The principal undergrowth was rattan. The natives are clearing and planting more of the island to coconuts and hope eventually to clear it completely.

Karindingen Island.—This island, about half a mile in circumference and between 10 and 20 feet above sea level at its highest point, was surrounded by extensive coral reefs and sand; the principal vegetation was mangroves.