Abstract Fluctuations in climate are key drivers of biodiversity patterns and can influence butterfly ecology, including distribution, abundance, and habitat use. However, few studies have examined these relationships in the Atlantic Forest, where ongoing urban expansion has reduced the original forest to small, isolated fragments. Thus, this study aimed to document the remaining butterfly fauna along the northern coast of Maceió city, Alagoas State, Brazil, and to assess its potential associations with weather variability and climatic seasonality. This study was conducted in a highly degraded area of the Atlantic Forest. Butterfly sampling was carried out weekly with entomological nets along pre-existing trails. Population analyses included abundance fluctuation curves, and climatic data were obtained from INMET to construct a climograph illustrating temperature and precipitation trends. Pearson correlations were used to assess relationships between monthly butterfly abundance and climatic variables. In 144 net hours of sampling effort, we recorded 924 individuals representing 92 species across six butterfly families. We found a negative association between butterfly abundance and temperature and a positive association with precipitation. These findings suggest that butterfly abundance in the evaluated region increases with higher precipitation and decreases as temperatures rise. Future research should focus on species-specific responses to weather fluctuations, especially changes in precipitation patterns due to global change. Because many butterflies may synchronise aspects of their life cycles with rainfall, shifts in precipitation could disrupt their development and resource availability.
Abstract Riparian ecosystems face degradation due to anthropogenic pressure, affecting biodiversity, food and water security, and the livelihoods. Adapting methods to assess riparian health locally and effectively is a pre-requisite for habitat monitoring and restoration interventions. In India, river health monitoring is largely limited to water quality and discharge measurements, with sparse biodiversity assessments. To fill the gap of a more comprehensive river health assessment, we adapted existing multi-metric indices. The indices are the fish-based Index of Biotic Integrity (IBI), the Bird Integrity Index (BII), a modified QBR (Qualitat del Bosc de Ribera), and the Riparian Strip Quality Index (RSQI). We considered plants, fishes and birds as representative taxa for terrestrial, aquatic and land-water transition zone, respectively. We used a nested hierarchical sampling approach to select nine one-km long segments (44 reaches) located along two streams of Moyar-Bhavani-Noyyil sub-watershed in southern India. The indices showed an overall decreasing trend moving downstream, and the lowest values were observed for agricultural (non-protected) sites. Only QBR and RSQI showed statistically significant difference across PA and NPA. BII could not be computed because of lack of statistically significant relationship between disturbance index and the bird metrics. RSQI offered limited insights but can complement IBI and QBR.
Seasonal variation in temperature and precipitation affects food availability for organisms. Tropical bats are trophically diverse, representing many feeding guilds, and can represent about half of mammalian diversity in tropical areas. Stable isotope analysis of nitrogen (delta 15N) in animal tissues permits inference on phenology of diet and trophic level through repeated sampling of a single tissue over time or by simultaneous sampling of multiple tissues that vary in isotopic turnover rate. The goal of our study was to use multi-tissue stable isotope analysis to investigate the phenology of diet (i.e., trophic-level switching) in bats. We sampled tissues of museum specimens from five tropical bat species representing different trophic guilds (insectivores, frugivores) and movement capacities (wide-ranging, narrow-ranging). We measured delta 15N in three metabolically latent (hair, skin, bone) and four active (heart, kidney, spleen, liver) tissues and generated mathematical model predictions of expected delta 15N values of these tissues based on their foraging guild. Specifically, we predicted that species with more sedentary movement patterns (i.e., narrow-ranging species) would have high among-tissue variation in delta 15N and species that move further and more often (i.e., wide-ranging) would have less delta 15N variation among tissues. Our results supported our predictions and suggest that the phenology of diet is detectable by multi-tissue isotope analysis using delta 15N.
Abstract Forest succession has been described to involve first a building phase followed by a thinning phase. How quickly tropical forests return to pre-disturbance levels is still unclear. We investigated changes in forest structure and tree community composition in a tropical forest in Singapore impacted by an unusually strong wind event in 2011, focusing on a hypothesised thinning phase. Stem densities of affected areas had declined by more than 50% from 2015 to 2023, while tree total basal area continued to increase slightly. Stem densities and basal area were not significantly different between affected and unaffected areas in 2023. Plot-level tree diversity also reduced between 2015 and 2023 in tandem with the loss of stems, but diversity in affected plots were still higher than that of unaffected plots in 2023. There was some evidence of a trajectory towards convergence in species composition between affected and unaffected plots, although species compositions were still different from the pre-disturbance state. Our findings provide insights on the legacies of wind disturbance on forests that endure beyond 12 years for the hurricane-free, equatorial tropics.
Abstract Reef fishes, especially herbivorous fishes, play key roles in maintaining the integrity of coral reef ecosystems. We selected four herbivorous reef fishes, namely Scarus ghobban, Siganus javus, Siganus canaliculatus and Siganus lineatus, and examined their feeding behaviour through gut content analysis and their abundance through underwater assessments on a patch reef in the Gulf of Mannar, southeast India during 2022–23. The results revealed that these fishes feed primarily on algae and seagrasses for these items made up more than 40% of their gut contents, with the exception of S. ghobban . And all four species feed on minimum amounts of other organisms, such as sponges, mollusks, crustaceans, etc., opportunistically or accidentally. The densities of these four species decreased within a year while the algal cover increased by around 1% presumably indicating the reduced grazing. This short-term study provides an insight into the importance of herbivorous fishes to maintain the delicate balance of the reef while warranting more focused long-term monitoring. It is apparent that the conservation of herbivorous species such as these four examined species is of critical importance in the context of global climate change in order to sustain the integrity of coral reef ecosystems in the Gulf of Mannar or elsewhere.
Only less than 2% of bat species use modified leaves as roosts called 'tents'. Few systematic surveys have been conducted to assess the abundance, diversity and density of tent-roosting bats and their tents. We present new records of plants used as tents and a new record of a tent-roosting bat species resulting from the first-ever bat tent survey conducted in the northern Atlantic Forest of Brazil. After two field visits for active search in the Murici Ecological Station (MES) in Alagoas state, 45 tents were found, with a density of three tents per hectare in a covered area of 3,340 m2 (0.34 ha). Three umbrella-type tents housed one individual of Artibeus obscurus each, all constructed on leaves of the hemi-epiphyte Philodendron ornatum (Araceae). This is the first record of A. obscurus using and probably modifying leaves to use them as a roost. One boat-type tent harboured two Vampyressa pusilla on the hemi-epiphyte Philodendron fragantissimum, representing the northernmost records of tents in the Atlantic Forest and for northeastern Brazil. The MES represents an important area for protecting tent-roosting bats in northeast Brazil, given the extensive historical deforestation and habitat loss within the Pernambuco Endemism Center and the northern Atlantic Forest.
Subterranean environments are distributed across diverse environmental and geographical landscapes. In this study, we assume that cave occurrences areas in Brazil occupy a multidimensional large-scale space and apply a site selection model that integrates environmental and geographical factors to identify distinct locations for speleological studies. Our approach combines these findings with existing knowledge on the distribution of Brazilian caves. The results reveal 45 unique environmental-geographic sites across five biomes and 19 Brazilian states. Our findings show that when both geographical and environmental heterogeneity are considered, the current knowledge of cave distribution in Brazil remains fragmentary, with particularly evident gaps in the Cerrado, Amazon rainforest, and Caatinga Biomes. These deficiencies almost certainly extend to the documentation of subterranean biodiversity. Most of the sites highlighted by the model contain few or no recorded caves in their surroundings, emphasizing the urgent need for systematic prospecting and biodiversity surveys in these underrepresented regions. Moreover, the lack of a publicly accessible, standardized database compiling primary records of cave biodiversity represents a major limitation for large-scale analyses. This shortcoming likely contributes to the repeated documentation of species within a narrow set of geographical and environmental contexts, thereby restricting comprehensive assessments of subterranean biodiversity across Brazil.
Selective logging is a prevalent practice in tropical forests that can impact wildlife health. Here, we investigate the effects of selective logging on the body condition of the Lowland tapir (Tapirus terrestris) in Jamari National Forest, Brazilian Amazonia. We apply a visual assessment protocol for scoring tapir body condition, based on camera trap images obtained in logged and unlogged areas. Tapirs from both areas presented high body condition scores (average of 4.2 on a scale of 1 to 5), and there were no significant differences in scores between areas (mean score unlogged = 4.2, sd = 0.54; mean score logged = 4.3, sd = 0.56), suggesting that logging does not affect tapir body condition. However, our results apply to the short term. Further research is necessary to understand the long-term implications of logging on the tapir.
Biodiversity is a key driver of ecosystem functioning, largely due to niche complementarity among species. Litter decomposition plays a crucial role in the cycling of matter, which supports other processes such as soil formation, primary productivity, and carbon storage. We examined whether litter mixtures with higher taxonomic diversity decompose more rapidly than those with lower diversity, and to what extent arthropods contribute to this pattern. We established a natural microcosm experiment within a remnant of Atlantic rainforest in Southeastern Brazil, where we set litterbags of equal weight (10 g), but varying numbers of litter species (from one to 16). Species identities were randomly assigned across replicates to control for species-specific effects. The litterbags remained in the field for 189 days, after which we extracted arthropods using Berlese funnels operated continuously for seven days. Richer litter mixtures decomposed faster and supported a higher abundance of arthropods. Previous studies reported varied results, which depended on specific species in the mixture and synergistic or antagonistic effects. Such variability is often attributed to site-specific conditions, experimental design, and the identity of litter species used. Importantly, our experimental design minimised the influence of particularly responsive species in high-diversity treatments while preserving natural field conditions. Higher abundance of arthropods in richer mixtures likely played a central role in accelerating decomposition. Soil fauna typically enhances decomposition through physical fragmentation, which increases surface area and alters structural properties of the litter. This mechanical disruption facilitates microbial colonisation and mineralisation by fungi and bacteria, thereby promoting more efficient decomposition.
Bait traps are a standard technique for studies of tropical butterfly community ecology and long-term assessment of population trends, with butterflies often regarded as biodiversity indicators. Fermented banana is the standard bait, but carrion baits, which may attract more individuals, species, and taxonomic groups, are also commonly used. However, the influence of carrion bait type on the butterfly sample is unknown. Here, we assessed the efficiency of three sources of carrion bait (shrimp, snapper, and tilapia), with banana as a comparison, in sampling butterflies in a west Ecuadorian premontane rainforest. Different carrion baits resulted in minor variation in sampled abundance and species diversity and minimal variation in species composition. All carrion baits recorded up to four times higher butterfly abundance than banana. Species composition was virtually identical among carrion baits, but only about half as similar to that sampled with banana. Choosing a consistent carrion bait for a monitoring scheme will facilitate temporal and spatial comparisons, but, given the minimal differences among carrion baits, practical considerations such as accessibility or cost may help determine bait choice. Finally, in agreement with other researchers, we support the simultaneous use of carrion and fruit baits to significantly increase sampled taxonomic diversity.
This study aimed to examine the response of land snails to five land-use types (protected forest, unprotected forest, cocoa plantation, teak plantation, and fallow) in the Lamto Reserve and its surrounding rural area. Snails were sampled monthly and for one year, using a combination of direct search and litter sieving techniques on 20 plots (5 plots of 400m2/land-use type). A total of 5471 individuals belonging to 53 species and 10 families were sampled. Abundance peaked in the protected forest and was lowest in rural land-use types, while species richness was highest in forests and the cacao plantation and lowest in fallow. However, the Shannon index and species composition showed no significant variation, in contrast to evenness. Eighteen of the 53 recorded species were associated with land-use types, mostly in the protected forest. Snail abundance was mainly influenced by canopy cover, soil calcium, and sand content, with a marked seasonal effect peaking during the rainy season. Canopy cover and litter depth emerged as the main determinants of diversity indices. Land-use changes significantly impact snail communities, underscoring the need for balanced conservation land management in tropical ecosystems.
Surveying nocturnal arboreal mammals in the tropics is challenging. Traditional methods are poorly suited to observing cryptic, often small-bodied mammals in the canopy. Subsequently, little is known about their ecology and behaviour despite the important functional roles they play within tropical forest ecosystems. We describe a method for observing behaviour from an elevated platform using thermal binoculars, evaluating the method against four criteria relating to species detected, field of view, potential disturbance, and richness of data. We surveyed for 205 h across 18 nights, recording 14 nocturnal arboreal mammal species with 126 independent events. Nocturnal arboreal species accounted for 61% of all observations. We found that elevating the observer aided the detectability of mammals by lessening the observation distance and the amount of foliage between the observer and the target. The observer also had a three-dimensional field of view and could follow mammals as they moved around the area. Thermal imaging emits no light source that will reveal the observer's presence, and so the risk of influencing mammal behaviour is likely to be reduced. This method shows potential to help fill behavioural knowledge gaps in nocturnal arboreal mammals in the tropics. Furthermore, the costs of the approach would make it accessible to many researchers.
Landscape changes due to forest loss and fragmentation challenges the maintenance of biodiversity. In general, these spatial processes affect the resource availability, species interactions, and microclimatic conditions - shifts that impair ecological assemblages' diversity. Through beta diversity, it is possible to understand how landscape changes affect assemblages' temporal variations. This study focused on analysing the effect of landscape composition and configuration on the assemblage heterogeneity of Cetoniinae beetles under a spatial and temporal lens. Beetles were sampled monthly from May to October 2022 using traps baited with fermented fruit in landscapes that comprised a gradient of anthropogenic disturbance. To estimate landscape spatial shifts, the amount of forest and agricultural lands, the amount of edges, and landscape diversity were estimated in the studied sites. A total of 649 individuals of six genera and nine species were collected. Spatially, more diverse landscapes had a higher temporal species turnover compared to less diverse landscapes; landscapes with higher amounts of edges maintained more abundant Cetoniinae assemblages compared to those with lower amounts of edges. Two distinct clusters according to the Cetoniinae assemblage were structured. This work is one of the first studies carried out with Cetoniinae in the Neotropical region. Our results present a first step to disentangle how spatial and temporal factors in a tropical fragmented landscape affect the patterns of Cetoniinae assemblages.
The vegetation in many African national parks is undergoing notable changes due to disturbances at various spatial and temporal scales. Understanding the responses of species can help with predicting future impacts of human-induced disturbance-related drivers on the vegetation in Mole National Park. This study aimed to examine how woody species react to disturbance-related factors in five vegetation types (woodland, savannah forest, riparian forest, swamp forest, and boval vegetation) across the park. We tested the hypothesis that the effects of wildfires, herbivory activities, invasive alien plant species, erosion, and bare ground on the tree community structure differ among the five vegetation types, as individual species respond differently to these drivers. Our results showed that the impact of fire regimes, invasive alien plant species, herbivory, erosion, and bare ground accounted for 59% of the low abundance of the individuals observed in the riparian and swamp forest vegetation types. Similar disturbances, especially fire regimes and invasive alien plants, also contributed to the presence of rarer species such as Afraegle paniculata and Isoberlinia doka in the woodland and boval vegetation types. However, the dominance and wide distribution of Detarium microcarpum, Combretum adenogonium, Terminalia avicennioides, and Icacina senegalensis in these two vegetation types suggest their resistance to these disturbance-related factors, particularly fire regimes, through the use of adaptive fire-cued mechanisms. We conclude that increased disturbances may lead to the extinction of many rarer species, while the few resistant and resilient species are likely to experience a decline in their populations in such resource-limited environments.
Leaf litter in headwater streams serves as an important energy source for the aquatic food web. However, the timing, magnitude, and source dynamics of leaf litter inputs into tropical montane streams have received less attention. Here we present an 8-year study of leaf litter inputs from two tropical montane first-order headwater streams in the Luquillo Experimental Forest, Puerto Rico that include a prolonged drought period and major hurricanes. Leaf litter was collected across different landscape sources such as canopy and riparian inputs, and litter transported from upstream. The different sources of leaf litter were compared to environmental variables (precipitation, wind, solar radiation, and temperature) to identify potential drivers of inputs to streams and exports. Leaf litter from upstream was the greatest contributor (50-95%) and can vary with storms and droughts. Transitions between dry and wet periods led to pulses of leaf litter in both streams. Increasing precipitation, solar radiation, and wind led to increased leaf litter inputs but varied across sources. The variable responses across sources to climatic events suggest that the timing and magnitude of litter inputs to headwater streams may be specific by source. Moreover, the results underscore the value in considering the forest cover of the watershed landscape in its entirety when quantifying organic matter inputs as they depend on upstream conditions that go beyond the immediate reach-adjacent riparian zone.
All animals, through their behaviours, modify their habitats. However, except for ecosystem engineers, for most species we know little about these modifications and their ecological consequences. Here, we assessed whether mantled howler monkeys in Mexico, through group defecations under sleeping trees, create microhabitats in the understory through increased dung beetle and rodent activity. In defecation and control sites, we sampled dung beetles with pitfall traps and rodents with camera traps. We also used experimental stations to measure dung removal and secondary seed dispersal by dung beetles and seed predation/removal by rodents. Supporting our hypothesis, we found that defecation sites had higher abundance of beetles and prolonged rodent visitation after one day and higher seed predation/removal after seven days. However, we found no differences in dung removal or secondary seed dispersal by dung beetles between defecation and control sites. Finally, contrary to our prediction, defecation sites had fewer photo records of rodents than control sites. Overall, our study shows that monkey group defecations under sleeping trees can create short-term microhabitat heterogeneity, although not necessarily in the expected direction. The next step will be to determine whether such effects can have longer-term consequences for forest ecology, such as promoting plant species coexistence.
Lepidopteran stemborers are among the most destructive pests of maize, sorghum, and sugarcane in Africa. Yet, data on their species composition and host range in Rwanda remain limited. This study provides the first comprehensive assessment of stemborer diversity, seasonal dynamics, and altitudinal distribution across eastern (low altitude), central (mid-altitude), and northern (high altitude) Rwanda. Surveys were conducted during both the rainy (maize growing) and dry seasons of 2023-2024, targeting infested maize fields and surrounding wild vegetation. A total of 2691 stemborer individuals were recovered from nine host plants, with 1474 (54.8%) from wild and fodder vegetation and 1217 (45.2%) from maize plantations. Species richness was highest in the mid-altitude zone, while overall abundance peaked at low altitudes. Busseola fusca was the most abundant in the high-altitude zone, Chilo partellus in the low altitude, and Sesamia spp. was concentrated in the mid-altitude. Seasonal variation significantly influenced population dynamic, with the highest abundance (1251; 46.4%) recorded during the dry season. Notably, Pennisetum purpureum (Napier grass) hosted 1156 (42.9%) of all specimens, highlighting its role as a key refugium during maize off-seasons. These findings underscore the ecological importance of wild vegetation in sustaining stemborer populations and suggest that wild vegetation, altitudinal, and seasonal factors must be considered in designing integrated lepidopteran stemborer pest management strategies.
Figs (Ficus spp.) are widely considered keystone resources in tropical ecosystems, yet mechanisms underlying their importance to primates are rarely assessed. We tested five hypotheses explaining the importance of figs for mantled howlers (Alouatta palliata) using a 10-year phenological dataset from southeastern Mexico. We monitored 57 trees representing figs and five other dietary species weekly from 2012 to 2021. The asynchrony hypothesis predicted lower intraspecific synchrony in figs, but we found no differences between figs and other species. The keystone hypothesis was strongly supported: this genus reduced weeks below critical thresholds by 59.5%, rescuing the community from scarcity in 72 weeks (14.7% of monitoring). During these events, figs contributed 20% of resources despite representing one-sixth of monitored taxa. The bet-hedging hypothesis predicted lower interannual variance in fig fruiting, but figs showed significantly higher variance than most species. The complementarity hypothesis predicted negative correlations between fig and non-fig phenology, yet we found positive correlations. The multiple cropping hypothesis predicted more fruiting cycles in figs than other species, but frequencies were equivalent (2.16 vs 2.13 cycles/year). Figs function as a keystone resource for mantled howlers not through unique phenological patterns but through reliable provisioning during critical scarcity periods, preventing resource bottlenecks that could otherwise limit the persistence of howler populations.
Dry ecosystems are critical to the global carbon cycle. Seasonally dry tropical ecosystems as a whole are botanically megadiverse, yet we have little understanding of how diversity impacts aboveground carbon, which is particularly noticeable for insular Asia. Across 133 vegetation plots on the seasonally dry tropical island of Flores, we used spatially explicit models to determine how land use impacts aboveground carbon stocks and whether this is dependent upon multidimensional diversity. Carbon is greatest in primary forests and least in agricultural landscapes. However, we find that land use interacts with phylogenetic and species diversity to shape carbon stocks. Across almost all models, quadratic effects of diversity were better predictors of carbon, indicating that whilst the initial build-up of diversity increases carbon, greater diversity causes carbon decline. Results suggest that future conservation plans will be needed to balance carbon storage with multidimensional diversity, which may offer distinct benefits for ecosystem resilience and services.
