Field data on the roosting ecology of a maternity colony of Pteropus vampyrus natunae in a peat swamp forest in Sarawak were collected for 19 mo. The colony moved between 10 roost sites and the diurnal home range (comprising only day-roost sites) was about 1120 ha. Two movement phases were observed within the diurnal home range. The first phase consisted of continuous movement between roost sites each month (August 1998 to January 1999, and August to November 1999), and this coincided with the months in which late pregnancies and pups dependent on mothers were seen. The second phase had almost zero or restricted movement each month (February to July 1999, and December 1999 to March 2000). Throughout the diurnal home range, the colony roosted in 20 families of trees (27 genera and 31 species). The bats tended to roost in certain species and sizes of trees.

Aerial photographs were used to assess changes in woody vegetation cover at 122 locations within a sandstone-plateau savanna woodland in the Victoria River region, Northern Territory, Australia. Despite locally variable vegetation responses, there has been little change in total woody vegetation cover since 1948. Thirty-three locations were also surveyed on the ground. It was found that sites for which vegetation cover had changed over the 50-y period were not significantly different from stable sites in terms of floristic composition, recent fire history, demographic stability among the dominant tree species, or edaphic setting. However, two of the dominant overstorey tree species – Eucalyptus tetrodonta and Eucalyptus phoenicea – showed significantly higher mortality on sites that had experienced vegetation cover decline since 1948. We suggest that observed changes in woody vegetation cover are a consequence of natural cycles of die-back and recovery of at least these two species in response to spatially heterogenous variables such as dry-season moisture stress. Although the widespread decline of fire-sensitive Callitris intratropica populations clearly indicates a historical shift from lower- to higher-intensity burning conditions within the study area, we reject the hypothesis of a landscape-wide process such as changing fire regimes or climatic change as the driving factor behind large-scale vegetation changes detected by aerial photographic analysis.

The phenology of calling activity and reproduction of a neotropical anuran community in French Guiana was studied during one rainy season. We investigated the correlation between calling activity, rainfall, temperature and water level in two ponds and recorded the occurrence of tadpoles of pond-breeding species. The study site contained 31 calling frog species, which were divided into groups according to reproductive mode. Increased rainfall was associated with increased reproductive activity in all groups, but temporal patterns in calling activity varied significantly between groups. Species with aquatic oviposition exhibited sporadic acoustic activity, aggregating into explosive breeding events following heavy rainfall. Species laying eggs in foam nests had the peak of calling activity at the start of the rainy season. Taxa with embryonic development on vegetation called mainly from middle to late wet season, being the only group which showed a significant correlation of calling with increasing water level. Dendrobatids with terrestrial oviposition and subsequent parental tadpole transportation were continuously active. Species with direct development or with non-feeding larvae were mainly active at the beginning of the rainy season. It is concluded that phenologies of calling activity in South American tropical anuran species are strongly influenced by abiotic factors like rainfall and availability of breeding sites. The temporal limitation of the rainy season forces species to adjust calling and reproductive activity according to their reproductive modes.

Increased shoot growth has recurrently been recorded following real or simulated shoot browsing, although responses may vary between different woody species. We investigated morphological responses to simulated dry-season browsing on Colophospermum mopane, Acacia tortilis, Grewia flava, Peltophorum africanum and Ziziphus mucronata, which differ in growth rate, occurrence of spines and use by mammalian herbivores. Treatment groups included a control, four clipping intensities and cutting at ground level. Responses were monitored during the following growth season on three annual shoots, located in the bottom, middle and top height interval, on each sapling. All five species showed compensatory growth responses, although no obvious relation was found between the strength of responses and growth rate or natural browsing pressure. The general pattern was an increased shoot length, shoot diameter, number of lateral shoots and shoot biomass with increased clipping intensity. These responses are probably an effect of the reduction of competing growing points and disrupted apical dominance. Growth responses were stronger in shoots with higher location on the sapling, which may reflect the pressure on saplings to attain a certain height to avoid browsing, reproduce and increase resistance to fire. We found no evidence of the number of spines being an induced defence in either of the two spinescent species studied.

Estimates of roosting habitat availability and population size using unbiased sampling regimes are completely lacking for any bat species. The use of conspicuous and accessible roosts in the developing, rolled leaves of Heliconia and Calathea plants by Thyroptera tricolor (Spix's disc-winged bat) provided an ideal opportunity to address this need. To assess roost availability and population size, the number of occupied and unoccupied leaves and bats in known areas in an area of lowland rain forest in north-eastern Costa Rica were quantified in 1998–99. A high density of leaves was available on any given day (mean: 43 leaves ha−1), but the density of roost leaves was low (mean: 2.5 leaves ha−1), corresponding with a low occupancy rate of 5.7 or 12% based on different methods of estimation. Developing leaves were available for 8–16 h in the preferred size range of leaves used by T. tricolor, and a maximum of 28–60 h, depending on the plant species. Using closed-population mark–recapture models, the 5.69-ha study area supported 261 individuals over a 4-mo period in 1998, corresponding to a density of 43 bats ha−1. These results have important implications for the results of studies on bat community structure and rarity, and for the behaviour and ecology of T. tricolor.

In dioecious plant species differences in morphology and resources between female and male flowers can have consequences for flower visitation rates. Female flowers sometimes lack pollen and can be less attractive to pollinators than male flowers. We studied the pollination ecology of the dioecious tree Commiphora guillauminii in a dry deciduous forest in western Madagascar. We recorded floral display, visiting insect species and visitation rates for female and male trees. The results showed that female trees produce significantly larger but fewer flowers per inflorescence than male ones. Number of flowers per tree did not differ between the sexes. During 270 observation-hours we observed 17 insect and two bird species visiting the flowers. Mean visitation rates of male flowers were 6.1 times higher than those of female flowers (1.07 vs. 0.18 visitors per flower h−1). Visitation rates to female and male trees showed similar daily and seasonal patterns. Fruit set (2.9%) was low, which could have been caused by pollinator or pollen limitation. This study suggests that dioecy may pose a risk for fruit set and, potentially, reproductive success for plant species with depauperate pollinator faunas on islands such as Madagascar.

The abundance and species richness of highly social bees (Apinae: Meliponini, Apini) were studied at 12 dipterocarp forest sites in Sabah, northern Borneo, using standardized honey-water baiting assays. The 12 sites were grouped in five localities varying in the degree and history of disturbance from selective logging. A baiting assay consisted of spraying diluted honey on vegetation along transects and recording bee arrival on the same day. Repeated assays of the same sites were run in two consecutive years, 1998 and 1999. One-way repeated-measures ANOVAs were calculated on bee abundance and species richness, with locality and year as independent factors. There were significant or marginally significant effects of forest locality on all measures of bee abundance and species richness. However, there were also significant interactions between year and locality on these variables, thwarting conclusions on the effects of logging on bee communities. The diverging results of the two years are likely related to spatio-temporal variation of flowering activity prior to and during the assays, with between-year differences being amplified by pronounced differences in climatic conditions (ENSO). Local or regional differences in flowering phenology complicate the application of resource-based baiting techniques for between-site comparisons of bee diversity.

Lake Titicaca is the largest freshwater lake in South America and one of the highest and oldest of the world's large lakes, but very little of its ecology is known. We report results from a study on the spatial variation of decomposition rate of Schoenoplectus tatora in Inner Puno Bay affected by direct wastewater discharges. The aims of the research were: (1) to evaluate the effect of benthos exclusion and the influence of other environmental factors on decomposition and (2) to map the decomposition rate in order to describe the spatial heterogeneity in the water body. We carried out the study at 21 sampling points using both fine-meshed and coarse-meshed litterbags to exclude and to allow detritivore action, respectively. Decomposition was on the average faster in the former than in the latter treatment. However, the difference decreased with increasing detritivore abundance, and reversed in the most densely populated waters of the bay. Coupled spatial dependence of the decomposition rate and temperature was observed. Both variables were related with the distance from the wastewater discharges, suggesting that thermal pollution constrains the decomposition rate within the inner bay. Detritivores did not change the general trend imposed by temperature, but their presence increased the spatial heterogeneity of the process.

Thirteen termite mounds and 13 similar-sized control plots were surveyed in central Zimbabwe in order to study large mammalian browsing and vegetation characteristics. The mounds supported almost twice as many tree species as the control plots and the woody vegetation was denser on mounds compared with the woodland plots. Species of woody plants were recorded along with the percentage of branches browsed (cumulative browsing score) by black rhino, Diceros bicornis, elephant, Loxodonta africana and other browsers combined. In addition we measured how the cumulative browsing score on three woody plant species, Acacia nilotica, Colophospermum mopane and Dichrostachys cinerea, which were common both on and off mounds, was related to the distance from mound centre. Both black rhino and elephant cumulative browsing scores were significantly higher on the mound plants compared with the woodland plots. Cumulative browsing score was negatively related to distance from the mound centre for Dichrostachys cinerea, Colophospermum mopane and Acacia nilotica. We propose that termite mound construction in miombo woodland contributes to sustaining populations of megaherbivores and perhaps some woody species in these areas.

Interspecific variation in seed size can affect seedling establishment in the light-limited understorey of rain forests. Large seeds with extensive seed reserves may allow seedlings to (1) persist in the deep shade, thereby increasing the likelihood of exposure to a canopy gap (Leishman & Westoby 1994, Saverimuttu & Westoby 1996); (2) promote growth, thereby allowing seedlings to reach higher light strata or to develop sufficient photosynthetic tissue to meet their energy needs in low light (Foster 1986); and (3) allow compensation for tissue losses to herbivores and pathogens (Armstrong & Westoby 1993, Foster 1986, Harms & Dalling 1997). However, comparisons of shade tolerance among species that vary in seed size have produced conflicting results; short-term seedling survival was strongly positively associated with seed size in several studies (Grime & Jeffrey 1965, Leishman & Westoby 1994), but only weakly in others (Augspurger 1984, Grubb & Metcalfe 1996).

In temperate trees, the extension growth history of stems and branches is easily inferred from the positions of the rings of over-wintering bud-scale scars, allowing one to assess environmental responses from surveys of saplings (Beaudet & Messier 1998, Canham 1988, King 2001). But tropical trees rarely show such distinct demarcations of growth flushes. Furthermore, the frequency of flushing may vary with tree size and environment, and a number of tropical species, often light demanding, show continuous leaf production and extension growth throughout the year (Coley 1983).

The production of domatia is a crucial step in the evolution of myrmecophytism (Fiala – Maschwitz 1992). Current models for the evolution of domatia predict that the ancestral state is one in which domatia production occurs later in a plant's ontogeny, while more derived ant-plants produce precocial domatia (Brouat – McKey 2000). I report that the neotropical tree Cordia gerascanthus L. represents a case of the former, in which domatia appear in mature trees. Through field and herbarium investigations, I have discovered that some C. gerascanthus individuals produce swollen, hollow, stem cavities that are ant-inhabited, while other C. gerascanthus individuals produce only solid stems. I suggest that C. gerascanthus, a species that produces domatia later in ontogeny, is an ideal system in which to investigate the basis of domatia evolution.