Several authors have reported associations between birds and monkeys in tropical forests (Boinski & Scott 1988, Huettmann 1999, Ruggiero & Eves 1998, Terborgh 1990). By such associations birds are considered to get some benefit, such as protection from predators and/or greater feeding efficiency (Terborgh 1990). In Southeast Asia, however, few reports on such interspecific associations have been available (galetti & McConkey 1998). The exception concerns several species of macaques living on Sulawesi Island, Indonesia (Fooden 1969). Associations between birds and Sulawesi macaques have been descibed by researchers as well as bird-watchers (Coates et al. 1997, Jepson & Ounsted 1997, Martarinza et al. 1994, Whitten et al. 1988). Local people in Sulawesi also know of associations between macaques and certain birds, particularly hair-crested drongo (Dicrurus hottentotus) and yellow-billed malkoha (Phaenicophaeus calyrhynchus). The farmers call these birds ‘burung monyet’ (monkey birds) and use the conspicuous calls of drongos and malkohas as signs of macaques' approaches to their fields (S. Matsumara, pers. obs.).

Some of the most spectacular examples of coevolution between flowers and their pollinators are reflected in their morphologies. Tongue length of insects and bill lengths of nectar-feeding birds are some of the most significant characters in pollination studies (Kearns & Inouye 1993). As Darwin noted as early as 1862, the evolution of deep floral tubes or spurs and long tongues of flower visitors can be explained by runaway coevolution (Nilsson 1988). However, such a process has only been shown to be likely in a few cases, e.g. between Malagasy orchids and hawkmoths (Nilsson et al. 1985). The pollinator of the Malagasy orchid Angraecum sesquipedale, with a 30 cm nectar spur, is a sphingid moth with a tongue of a similar size (Darwin 1862, Nilsson 1998). However, most studies of such extreme pollination specialization also report that the interaction is asymmetrical, i.e. the pollinators interact with a guild of plants, whereas the plant often depends on only a few pollinators (Johnson & Steiner 1995).

The importance of disturbances for the dynamics of tropical forests has been described by Whitmore & Burslem (1998). Among the phenomena which they classify as large scale disturbances are those caused by wind. The most extensive of these occur within the hurricane (cyclone) belt (10-20° from the equator) but outside this belt large blowdowns of trees are known to occur, perhaps most spectacularly in the Brazilian Amazon (Nelson et al. 1994). There is evidence that rare wind storms influence the dipterocarp rain forests of Peninsular Malaysia, 2-6°N. One famous storm in November 1880 which devastated hundreds of square kilometres of forests in Kelantan, north-east Malaya, was probably an aberrant cyclone (Wyatt-Smith 1954). Smaller windstorms which have blown down several hectares of forests have been reported from Malaysia including Borneo (Ashton 1993) but their frequency and extent have not been well documented (Whitmore & Burslem 1998). At Barito Ulu, Central Kalimantan, one such storm occurred recently and the fortuitous combination of a well patrolled trail system and the localization of the storm has allowed a detailed assessment of the forest damage.

Most butterfly species forage for nectar, which provides them with carbohydrates and to some degree other nutrients, such as lipids and amino acids (Boggs 1987). A small number of genera feed exclusively on rotting fruits and plant sap (DeVries et al. 1999). Some 40 passion vine butterfly species, belonging to the genus Heliconius Kluk and a closely related monospecific genus Laparus Billberg gather nutrients from pollen feeding (Brown 1981, Gilbert 1972). Although common in bees, wasps, flies and beetles (Roulston & Cane 2000, Thorpe 2000), pollen feeding is rare among lepidopterans. In order to collect pollen, adults scrape anthers with the proboscis and gather the grains. The pollen is then incubated in solution and the amino acid-rich solution is ingested. The empty pollen grains are eventually discarded (Gilbert 1972, Krenn & Penz 1998). Pollen feeding provides amino acids that are used for egg production and somatic maintenance in adult Heliconius (Dunlap-Pianka 1979, Gilbert 1972, 1991). The most common sources of pollen are flowers of species in the genera Psiguria Neck. ex Arn. and Gurania (Schltdl.) Cogn. (Cucurbitaceae). The home range of an individual Heliconius will encompass one to many pollen plants (Murawski & Gilbert 1986).

Given their difficulty of access, the canopies of tropical rain forests are considered a last frontier of biological/ecological research (Lowman & Nadkarni 1995). Climbing techniques are arduous and do not reach the tips of branches; towers, cranes and walkways limit the spatial exploration of the forest.

An understanding of the abundance of organisms is central to understanding ecology, but many population density estimates are unrepresentative because they were obtained from study areas chosen for the high abundance of the target species. For example, from a pool of 1072 lizard density estimates that we compiled from the literature, we sampled 303 estimates and scored each for its assessment of the degree to which the study site was representative. Less than half (45%) indicated that the study area was chosen to be representative of the population or habitat. An additional 15% reported that individual plots or transects were chosen randomly, but this often indicated only that the sample points were located randomly within a study area chosen for its high abundance of the target species. The remainder of the studies either gave no information or specified that the study area was chosen because the focal species was locally abundant.

The Abstract and Table 2 within this paper contained some errors. The corrected versions appear below. The publishers would like to apologise to their readers for these errors.