Bats are important but understudied pollinators in the Palaeotropics, and much about their interactions with night-blooming, bat-pollinated plant species is still unknown. We compared visitation times to flowering and fruiting plant resources by nectarivorous bat species (obligate pollinators) and frugi-nectarivorous bat species (facultative pollinators) throughout the night to examine the temporal variability that occurs within Pteropodidae foraging. Timing of pollination is an important determinant of plant reproductive success and more temporally restrictive than fruit dispersal. We netted 179 nectarivorous bats and 209 frugi-nectarivorous bats across 367 total mist-net h at five plant species providing floral resources and six plant species providing fruit resources. We found that all three nectarivorous bat species in southern Thailand forage significantly earlier in the evening (20h30 versus 22h00), and over a significantly shorter time interval (1.73 h versus 3.33 h), than do the five most commonly netted frugi-nectarivorous species. These results indicate that the two feeding guilds may be imposing different selective pressures on bat-pollinated plant species and may comprise different functional groups. We propose that the observed differences in bat foraging times are due to temporal constraints imposed by the rewards of the plant species that they visit.

Dipterocarp seedling populations arising from a 1996 mast fruiting in closed-canopy primary lowland rain forest in Sabah, Malaysia, were monitored through the 1997-8 El Niño event to investigate the effects of drought and other factors on dipterocarp regeneration. Of particular interest was the influence of herbivory and its relation to drought, since water stress is known to influence herbivore performance. For seedlings with less than 10% leaf damage, mortality during a 6-mo period spanning the driest part of the drought was three times higher than mortality in the previous and subsequent 6-mo periods (∼10% vs. ∼30%). Leaf production was also higher during this period. Survival was positively related to leaf number and negatively related to leaf damage. Dryobalanops lanceolata was the tallest and leafiest species, and had low levels of leaf damage. Depending on sample period, abscission of leaves with more than 50% damage was between two and three times more likely than those with less than 10% damage. Mortality of seedlings defoliated by more than 50% was around twice that of seedlings defoliated by less than 10%. However, fewer than 10% of seedlings were defoliated by more than 50% at any time. The effect of defoliation did not seem to be altered by drought. Defoliation levels increased after the drought, perhaps due to a resurgence of insect populations. Drought may become a more important influence on dipterocarp regeneration in future, since El Niño events are thought to be increasing in frequency.

The maintenance of biodiversity in tropical forests is thought to be dependent on fine-scale mechanisms of niche partitioning that allow species to coexist. This study examined whether three species of short-tailed fruit bat that co-occur at a lowland tropical forest site in Costa Rica (Carollia castanea, C. perspicillata, C. sowelli) avoid inter- and intraspecific competition through dietary specialization on species in the genus Piper. First, dietary composition was examined using faecal samples (N = 210), which yielded three main findings: (1) bat species and sexes vary in overall reliance on fruits of Piper, with a higher percentage of seeds of Piper detected in the diets of C. castanea (98.2%) and females (91.5%); (2) adults and juveniles partition species of Piper by habitat, with a lower percentage of mid- to late-successional species of Piper detected in adults (20.8%); and (3) overall, there is a strong dietary overlap among and within the three species of Carollia. Second, controlled choice experiments were conducted with individual bats (N = 123) to examine preferences for different species of Piper. These results indicated few differences in Piper preference based on bat species, sex, age class or reproductive status, suggesting preference is not the primary mechanism shaping the observed differences in dietary composition. Overall, the dietary composition and preference similarities suggest there is strong competition both among and within the three species of Carollia for food resources.

During the non-breeding season, shorebirds, a large and important group of wetland vertebrates, divide their time between foraging, resting and maintenance activities. We examined factors affecting time budgets, foraging techniques and rates, and spacing patterns of 14 to 92 individuals each of 10 shorebird species spending the non-breeding season in Cayo Guillermo, Cuba. We hypothesized that all species would spend the majority of their time foraging. Time spent foraging ranged from 20–85% of total time and was significantly negatively related to average body size. Apparent aggression (e.g. chasing or being chased) occurred in < 10% of individuals in all species and was not related to maximum counts of conspecifics. Aggression was most common in the black-necked stilt but did not vary in frequency as a function of activity. Vigilance varied in occurrence from 0–53% of individuals, but the frequency was not related to maximum counts. Intraspecific distances were generally greater between foraging than non-foraging birds. For most species interspecific distances were similar to intraspecific distances during foraging but greater than intraspecific differences during non-foraging, suggesting some overlap in foraging habitat and niche partitioning during non-foraging. Shorebirds that used primarily tactile techniques foraged closer together than primarily visual foragers. Low rates of aggression, as an index of potential competition, suggest that species-specific energy requirements rather than competitive interactions are the main determinants of foraging behaviour on these tropical non-breeding grounds.

Patches of wooded vegetation in nutrient-poor grassland characteristically contain high soil moisture and nutrient availability compared with surrounding grassland. These ‘islands of fertility’ appear stable in size, suggesting that tree recruitment at the patch boundary is limited. We hypothesize that tree establishment in adjacent grassland is limited by (1) competition for resources, (2) fire or (3) herbivory. In a South African grassland, we measured moisture availability and conducted a bioassay experiment to analyse whether soil nutrient limits tree recruitment at the patch boundary. We thus measured nutrient concentrations of maize plants grown in patch, boundary and grassland soil. To investigate whether browsing or fire affected tree seedlings at the patch boundary, we burned plots including patches, and used fences to exclude browsers. Neither soil moisture nor nutrient availability at the boundary differed from inside the patches, suggesting that tree recruitment at the boundary is not resource limited. Both fire and browsing combined caused a significantly lower tree seedling growth at the patch boundary, suggesting that these two factors can impede tree recruitment. The balance between positive feedback mechanisms facilitating tree recruitment, and the negative impact of fire and browsing can explain the apparent stability of these islands of fertility.

Cape clawless otters Aonyx capensis and African mottled eels Anguilla bengalensis were suspected of reducing numbers of rainbow trout Oncorhynchus mykiss in the upper Kairezi River, Zimbabwe, by preying on them and competing for the river crab Potamon perlatus. The analysis of otter, eel and trout diets showed that this is unlikely. Trout was an unimportant prey item for otters, none were found in the stomachs of 13 large eels, and any predation was probably minimised by the low densities of these predators. Some competition was probably present because crabs occurred in the diets of otters (relative occurrence 41.9%), eels (63.2%) and trout (7.4%), but it was impossible to quantify. Since these predators shared the crab food resource, the guild concept provided the basis for an analysis of their potential competitive relationships. Comparisons between the sizes of crabs selected and those available suggested that resource partitioning was occurring. Trout selected small crabs from the invertebrate drift, and because they were restricted by their mouth gapes. Otters and large eels ate larger, more abundant crab sizes; it is proposed that they instead partition resources spatially by feeding in separate micro-habitats. Intraguild predation by otters on eels may benefit trout by reducing competition for aquatic insects. Competition within the guild probably recedes in the dry season, when eels become inactive.

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.

Little is known about the relationship involving arbuscular mycorrhizal (AM) fungi and functional groups of plants that characterize different phases of tropical succession. We appraised the AM infection intensity of root cortex and spore density in the soil in sites over tropical successional gradients (grassland, secondary forest and mature forest) for several years in Araucaria, Atlantic and Pantanal ecosystems in Brazil. The intensity of AM infection decreased with advancing successional stages in all ecosystems and it was around 60–80% in early stages of succession, 37–56% in secondary forests and 19–29% in mature forests. Similarly, the AM spore number also decreased with advancing succession and was the highest in early stages (73–123 g−1), intermediate in secondary forests (32–54 g−1) and lowest in the mature forests (10–23 g−1). To verify whether such reductions influenced the potential of AM inoculum in soil, seedlings of Heliocarpus popayanensis (Malvaceae) were grown as test plants in soils obtained from five grasslands, five young secondary forests, and five mature forests in the Atlantic ecosystem. The soil inocula from the grasslands and secondary forests were 7.6 and 5.7 times more effective in stimulating seedling growth than inocula from the mature forests, respectively. Our results show that plant species in grasslands and young secondary forests stimulate the multiplication of AM fungi, leading to a higher potential of the AM inoculum. In later-successional stages, plant investment in AM fungi decreases and the potential of the AM inoculum is also reduced.

A survey of the 1:100,000 topographic maps of Papua New Guinea revealed that there are about 5383 freshwater lakes in the country. They range in size up to 647 km2 but the majority are less than 10 ha. They are found at all altitudes to over 4000 m but most are situated below 40 m in the floodplains of the Fly, Sepik and Aramia rivers. The majority of lakes are undoubtedly shallow but depths range up to 360 m. The lakes were formed in at least 20 different ways but the majority by fluviatile action. The few data on chemical and physical conditions suggest that most lakes are chemically poor with low light penetration and low pH values. With the possible exception of the macrophytes the fauna and flora of the lakes are virtually unstudied, particuarly from a quantitative aspect. Most lakes are probably polymictic.

We tested the hypothesis that species of a diverse leaf-litter ant community are separated by the temperature preferences of their broods along a thermal gradient. Therefore, temperature preferences of brood-tending workers from 41 ant species co-occurring in four types (alluvial, limestone, kerangas and dipterocarp forest) of primary rain forest in Sarawak, Malaysia were measured in an experimental set-up. Preferred temperatures of species ranged from 16.0 °C to 31.7 °C, with the median at 25.8 °C. The ten commonest species (n ≥ 4) showed significantly different temperature preferences. In particular, species of the genus Pheidole differed clearly in their preferences over a broad range of temperatures. Temperature preferences varied significantly among ant assemblages from different forest types and nest sites. Experimentally obtained temperature preferences of species correlated significantly with vegetation density in the plots inhabited by the respective species, but not with plot canopy cover. When we tested the temperature preferences of all ant species with null models for niche overlap, we found a significant niche separation only among the tested species from the kerangas. Our results suggest that nest temperature is an important ecological factor for leaf-litter ants in rain forests on Borneo, but other factors may override its influence during community assembly.

Variation among forests in environmental and biotic conditions may strongly influence seed fate with important consequences for the abundance and distribution of plant species. Here we examine the post-dispersal seed removal rates of six pioneer species (Cecropia peltata, Miconia argentea, Luehea seemannii, Trema micrantha, Apeiba aspera and Jacaranda copaia) from the soil surface at five sites in Panama varying in elevation (0–1100 m) and seasonality (0–4 mo dry season). We compared removal rates of washed seeds placed in vertebrate exclosures, invertebrate exclosures, and unprotected controls in January and June. Overall, removal rates of unprotected seeds were similar among sites. Almost all seed removal could be attributed to litter ants in two subfamilies (Myrmicinae and Ponerinae). Little or no removal was recorded from invertebrate exclosures while vertebrate exclosures had no effect on removal either in lowland and montane forests. Seed removal rates were high for four animal-dispersed species (mean 45% removed over 2 d), whereas two wind-dispersed species were largely untouched (mean 2% removed). These results indicate that seed dispersal characteristics, rather than site characteristics, may be the strongest determinant of the post-dispersal seed fate of pioneers.

Litterfall is one of the most important pathways through which nutrients are recycled in the terrestrial biosphere. In tropical soils, which are generally low in essential nutrients such as phosphorus and cations, the flux of nutrients through litterfall is particularly important to sustaining CO2-uptake capacity; however, questions remain over the role of altitude in altering litter nutrient cycling rates among tropical forest ecosystems. Here we examine litterfall, carbon (C), nitrogen (N) and phosphorus (P) fluxes through litterfall over an altitudinal gradient in the coastal Atlantic Forest located on the northern coast of the State of São Paulo, Brazil. Litterfall was collected twice a month for 1 y (April 2007–March 2008) using 30 litter traps placed in four different forest types arrayed by altitude – coastal forest (sea level), lowland forest (50–200 m asl), submontane forest (300–500 m asl) and montane forest (1000 m asl). Litterfall mass-fluxes decreased with increasing altitude, from ~9 Mg ha−1 in lowland forests to 7 Mg ha−1 in higher-altitude ecosystems. Contribution of reproductive organs to litterfall was significantly greater in lower than in higher altitudes. Litterfall N and P fluxes were higher in the lowland forest vs. other forest types, pointing to strong altitudinal controls over nutrient cycling. Furthermore, nitrogen-use efficiency (NUE) was lower and litter δ15N was higher in the lowland site providing additional evidence for lack of N constraints to productivity in lowland of the south-eastern Atlantic Forest.

Artibeus watsoni (Chiroptera: Phyllostomidae) was found in Costa Rica to alter the shape of 11 species of broad-leafed plants in the families Araceae, Cyclanthaceae, Maran-taceae, Musaceae, and Palmae to form diurnal roost sites. The plant most commonly used for tent construction was Anthurium ravenii (Araceae). Bats create a tent on A. ravenii by severing the basal 2 to 5 lateral nerves at a distance of 5 to 10 mm from the midrib; the entire margin of the leaf then collapses downward to form a pyramid-shaped tent. The number of altered leaves per plant ranges from 1 to 4 with a mean of 2.1. A. watsoni appears to be selecting leaves of medium size and low within the plant. The size, shape, and location of leaves selected is consistent with the hypothesis that tent construction provides bats with roost sites that will be available to them for a long period of time and provides protection from both predators and the elements, thus conveying a selective advantage to the bats.

Food webs of streams draining tropical rain forests on Costa Rica's Pacific and Caribbean coasts were examined in the 1980s via dietary analyses, and the same streams were surveyed again in 2004 to compare trophic structure based on analysis of stable isotope ratios of fish, macro-invertebrate and plant tissues. Estimates of species’ trophic positions (TP) were calculated from stomach-contents data (51 species; 5420 specimens) and compared with TP estimates derived from analysis of nitrogen isotope ratios (82 taxa; 240 samples). Coefficients of determination for TP based on dietary versus isotopic analysis ranged from 0.18 (Quebrada Camaronal, Corcovado) to 0.73 (Quebrada Estacion, Tortuguero). Consumer taxa within all four streams spanned a broad range of carbon isotope values, indicating assimilation of variable proportions of carbon from periphyton and terrestrial vegetation that in all but one of the streams had similar δ13C values. Approximately half the consumers in all four streams had carbon ratios heavier than any of the in situ production sources examined. This pattern could be explained by consumption of other production sources that were not sampled, including periphyton taxa with variable carbon isotope signatures, or migration of prey and/or consumers between these freshwater and coastal marine habitats.

The importance of figs as keystone resources depends partly on their year-round fruiting pattern. However, most non-equatorial fig species show seasonality in reproductive phenology. If fig and other species' fruiting peaks coincide, the importance of figs as key resources during lean fruiting periods may be reduced. Fig and other forest tree phenology was studied in a deciduous and an evergreen site in the Western Ghats, southern India, from January 1991 to May 1992. In the deciduous site, most non-fig flowering and leaf flushing occurred during the two dry seasons, while most fruiting occurred during the dry and early wet seasons. In the evergreen site, all non-fig tree phenological stages – flowering, fruiting and leaf flushing – were concentrated during the two dry seasons annually (dry and post-monsoon). Individual fig trees produced crops one to three times annually, at different times of the year for different trees. Fig community fruiting peaks in the evergreen site coincided with fruiting peaks of the other forest trees, but in the deciduous site occurred slightly offset from non-fig fruiting peaks. The role of figs as key resources is likely to differ among forests, and to depend on factors such as diversity of fruiting pattern among fig species, fig tree density and territoriality of frugivores.

Many rain-forest trees in South-East Asia, including the dominant canopy family Dipterocarpaceae, reproduce in gregarious mast-fruiting events once every 2–11 y (Ashton et al. 1988). The dominant hypothesis for the evolution of masting is that predators are incapable of consuming mast seed crops, so that natural selection has favoured parent trees that fruit in synchrony (Janzen 1974, 1976). Mast flowering and fruiting are visually spectacular and quantified in harvest records for dipterocarp species producing large, oil-rich tengkawang seeds (Curran et al. 1999). Seedling recruitment following a mast is less obvious and has no immediate commercial value. However, a number of pulses of recruitment have been documented (Ashton et al. 1988, Chan 1980, Fox 1972, Liew & Wong 1973). These, together with general acceptance of the satiation hypothesis, have led to the widespread assumption that masts reliably increase seedling density and generate distinct seedling cohorts (Whitmore 1998). Indeed, foresters in Malaysia and Indonesia often recommend harvesting only after a mast, to ensure high densities of seedling regeneration.

The natural seed shadow created by gibbons (Hylobates mulleri×agilis) in Central Kalimantan, Indonesia, was monitored over 11 mo to discern the role of gibbons and post-dispersal events in the spatial pattern of seed germination. Variability in the content and distribution of 183 scats was used to determine which, if any, scat characteristics influenced seed fate. Nine scat characters were evaluated: (1) seed number; (2) number of seed species per scat; (3) scat weight; (4) seed load; (5) rainfall; (6) scat density; (7) distance to nearest fruiting tree; (8) ripe fig abundance; (9) non-fig fruit abundance. More than 99% of monitored seeds were killed, removed, or had germinated during the monitoring period. Vertebrates killed or removed most seeds (86%) and the probability of them moving seeds was highly dependent on non-fig fruit abundance at the time of deposition; factors (2), (6) and (7) also influenced seed removal/predation by vertebrates, depending on whether seeds were deposited in peak or non-peak times of consumption. Insect predation (2% of seeds) occurred mainly in scats that were deposited in months of high ripe fig abundance, while the actual chance of a seed germinating (11% of seeds) was influenced by non-fig fruit abundance at time of deposition and number of species in the original scat. The gibbon-generated seed shadow was profoundly altered by post-dispersal events and variation in the characteristics of the shadow had little lasting impact on the probability of seeds germinating.

The ecological impacts of introduced species can reveal mechanisms underlying habitat selection and behaviour. We investigated the habitat use of native frog species and the invasive cane toads (Rhinella marina) in tropical northern Australia to measure overlap in habitat use, and to test if the presence of the cane toad influences frog behaviour. Native frog species and the cane toad both preferred habitats close to water and unvegetated holes. However, native frogs were found further from water (on average 19.4 m) than were toads (on average 12.6 m), and preferred areas with higher vegetation (8–50 cm) than did toads, which were more abundant in vegetation lower than 8 cm. For both types of anuran, the next neighbour was more often of the same type (89% in frogs, 52% in toads) than expected by chance (observed ratio: 75% frogs vs 25% toads), reflecting these differences in habitat use. Our counts of frog abundance increased on average 14.5% in areas from which we removed cane toads temporarily. This result suggests that cane toads inhibit the activity of native anurans either by inducing avoidance, or by reducing activity. By modifying the behaviour and spatial distribution of native taxa, invasive cane toads may curtail activities such as feeding and breeding.

Litter decomposition is a fundamental process for nutrient cycling but we have a limited understanding of this process in disturbed tropical forests. We studied litter decomposition over a 10-mo period in a seasonally dry Amazon forest in Mato Grosso, Brazil. The study plots (50 ha each) included unburned forest (UF), once-burned (BF1) and forest burned annually for 3 y (BF3). We measured understorey density, litter depth, canopy openness, temperature and relative humidity in the plots. Decomposition experiments took place using 720 litterbags filled with approximately 10 g of natural abscised oven-dried leaves. To test the effects of fire on soil meso- and macrofauna, the litterbags had either a fine (2 mm) or coarse (with 1-cm holes in side) mesh size. Litterbags were collected and reweighed 2, 4, 6 and 8 mo after being placed on the forest floor. All forest structure variables were significantly different across plots: BF3 was hotter, less humid, had the highest degree of canopy openness, lowest understorey density and the shallowest litter depth. Litter decomposition (mass loss) was similar in the once-burned and unburned plots, but declined more slowly in BF3. In addition, decomposition was slower in fine-mesh litterbags than coarse-mesh litterbags in BF3, but there was no difference between mesh sizes in BF1 and UF. It is likely that changes in forest structure and microclimate explain the lower decomposition rates in BF3. These results show the importance of recurrent fires, but suggest that single understorey fires may not have long-term negative effects on some ecological processes in seasonally dry Amazonian forests.

Primary tropical forests comprise a mosaic of mature, gap and building phase patches, resulting in great spatial variation in the distribution of foliage. Light may consequently penetrate into the forest interior over a wide range of angles. It thus seems possible that understorey tree species might be adapted for distinct understorey light conditions. At the Cocha Cashu Biological Station in Madre de Dios, Peru, there are two understorey treelets distinguished by contrasting crown architectures. One, Neea chlorantha (Nyctaginaceae), possesses a much-branched superstructure and displays a smoothly contoured shell of drooping elliptical leaves. The other, Rinorea viridifolia (Violaceae), displays planar arrays of horizontally-oriented obovate leaves held on whorls of stiffly radiating horizontal branches.

With the aid of hemispherical photography and the program CANOPY, the light environment at large within a 2.25-ha permanent tree plot, and above and below the crowns of Neea and Rinorea treelets, was investigated. Available light (measured as uncorrected indirect site factor (ISFU) in CANOPY) at control points showed a log-linear increase with height from 2.1 to 14.2 m. The relative amount of lateral illumination also increased with height. Photographs were taken just above and below the crowns of 50 Neea and 50 Rinorea treelets. Neea crowns were more effective at intercepting light from overhead sources, whereas Rinorea crowns were more effective at intercepting light from lateral sources. Adult Neea and Rinorea treelets occurred at locations in the forest where they were exposed to differing angular distributions of incident light, suggesting that the two species were engaged in a form of resource partitioning, a conclusion that is in conflict with the non-equilibrium model of tropical forest tree species diversity. It is suggested that tropical tree species diversity is, at least in part, a product of adaptive specialization to a spatially heterogeneous light environment.