Birds from North Borneo / University of Kansas Publications, Museum of Natural History, Volume 17, No. 8, pp. 377-433, October 27, 1966

by Max C. Thompson

ECOLOGICAL AFFINITIES OF THE AVIFAUNA AT QUOIN HILL

More time was spent at Quoin Hill than at any other locality. Fifty five of the more common and hence best-known birds are listed in Table 1 together with their primary and secondary preferences of habitat. The habitat distribution of the birds shows the amount of secondary utilization of habitats by birds that occurred predominantly in one habitat. Cocoa was utilized by 6.2 per cent of the birds of the primary forest, and 88.8 per cent of birds of the secondary forest. This indicates that cocoa is an effective substitute for secondary forest for some birds. Of the species of the primary forest, 18.7 per cent occurred also in secondary forest; thus, three times as many species of primary forest utilized secondary forest as utilized cocoa. This too might be expected, since "secondary" forest is of frequent natural occurrence and an ancient feature while the comparatively simple cocoa plantings are new and artificial.

TABLE 1.—Habitat preferences of 55 Quoin Hill birds.

X=Primary O=Secondary Species	Primary forest	Secondary forest	Cocoa plantations	Fluviatile water	Abaca
Treron curvirostra		X
Cacomantis merulinus		O	X
Chalcites malayanus			X
Phaenicophaeus chlorophaeus		O	X
Harpactes diardi	X
Harpactes duvauceli	X
Alcedo euryzona				X
Ceyx erithacus	X
Eurystomus orientalis		X	O
Calorhamphus fuliginosus		O	X
Megalaima chrysopogon		X	O
Megalaima henrici	X		O
Sasia abnormis	O	X
Meiglyptes tukki		X
Dryocopus javensis		X	O
Chrysocolaptes validus		O	X
Eurylaimus ochromalus		O	X
Pitta guajana	X
Coracina fimbriata			X
Aegithina viridissima			X
Chloropsis cyanopogon		X
Irena puella		X
Pycnonotus brunneus			X
Criniger bres		X	O
Criniger phaeocephalus	X
Criniger finschii			X
Hypsipetes criniger		X	O
Copsychus pyrrhopygus	X
Copsychus stricklandi		X	O
Enicurus ruficapillus				X
Pellorneum capistratum	X
Trichastoma malaccense	X	O
Trichastoma sepiarium		X
Malacopteron magnum	X	O
Malacopteron magnirostre	X	O
Kenopia striata	X
Stachyris poliocephala		X
Alcippe brunneicauda	X		O
Orthotomus atrogularis		X
Orthotomus sepium		X	O
Rhipidura perlata	X
Muscicapa dumetoria	X
Rhinomyias umbratilis	X
Hypothymis azurea			X
Anthreptes simplex			X
Anthreptes rhodolaema			X
Nectarinia hypogrammica		X
Arachnothera longirostris					X
Arachnothera flavigaster					X
Arachnothera chrysogenys					X
Arachnothera affinis					X
Zosterops everetti		O	X
Lonchura fuscans		X	O
Oriolus xanthonotus		X	O
Platysmurus leucopterus		X	O
Total Primary	16	18	14	2	4
Total Secondary	1	8	14	0	0

The avifauna at Quoin Hill was a mixture of montane, submontane, and lowland species. Smythies (1957:527) defines four altitudinal areas of distribution: Higher Montane, Montane, Submontane, and Lowland. Higher Montane birds have not been recorded on mountains the summits of which are lower than 5,000 feet, although on higher peaks the actual lower limit of occurrence may be considerably below 5,000 feet. Montane birds have not been recorded on mountains the summits of which are lower than 3,000 feet, although specimens may have been taken below that altitude on higher peaks. Submontane, as defined by Smythies, is a comprehensive term applied to birds occurring from sea level to an elevation of 5,000 feet but ordinarily not found away from mountainous country. The Lowland birds normally range from sea level to 3,000 feet. Of the 125 species of birds observed at Quoin Hill, 1.6 per cent were Montane, 14.4 per cent were Submontane and 84 per cent were Lowland species. The distribution of birds 12 miles north of Kalabakan closely resembled that at Quoin Hill except for the total absence of Montane species and an increase of Submontane species to 25 per cent. The observation of fewer species (48) can be attributed to the nearly uniform habitat.

The avifauna in the moss forest 5.5 miles southwest of Tenom was unusual in that 45.4 per cent consisted of Lowland species; this locality lies 4,000 feet above sea level, yet only 27.3 per cent of its species were Submontane and 27.3 per cent Montane. If one looks at these figures from the standpoint of the actual importance of the three groups at this place, however, a different picture emerges. Some of the Lowland species were seen only once while I was there and few were common, while all of the Submontane and most of the Montane forms were more or less common.

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SEASONALITY OF BREEDING

The breeding season in North Borneo.—Birds in the Quoin Hill area of eastern Borneo seem to breed most commonly in June, July, and August. Table 2 lists 34 of the more common species at Quoin Hill for which evidence on breeding was available. The actual evidence was provided by females with active brood patches or active ovaries, males with enlarged testes, birds in juvenal plumage, or birds actively in annual molt. From such data dates of presumed breeding were extrapolated. In Table 2, the solid black lines indicate dates for which both male and female were in breeding condition. The dotted lines indicate enlarged testes but no evidence of breeding in females. In the bottom line of Table 2, the figures indicate the percentage of the population breeding in any one month. For instance, 2.9 per cent of the birds were breeding in March, but 73 per cent were breeding in June. Rainfall records from the Cocoa Research Station from April, 1959, to December, 1964, were available to me. These data, along with the average for each month, are given in Table 3. There appears to be little correlation between rainfall and breeding season at Quoin Hill. A true dry season in the Quoin Hill area does not occur, but monthly rainfall has varied from 0.57 inches to 21.27 inches in a single year.