Biotropica

There are few studies of day-roosting ecology of bats inhabiting the southernmost forests of South America, where cool summer temperatures and land management practices pose several challenges. The goal of the present study was to describe day-roosting habitats and patterns of thermoregulation in two bat species occurring on Tierra del Fuego, Myotis chiloensis (Chilean myotis) and Histiotus magellanicus (southern big-eared brown bat), during late spring. To do so, we tagged 17 bats with temperature-sensitive radio-transmitters, located 17 day-roosts, and collected 81 days of skin temperature data. We concurrently recorded ambient air temperature to determine its effect on torpor use. Both species were found roosting in large diameter (77.8 {+/-} 6 cm), typically live, Nothofagus pumilio trees (lenga) located on the edges of forest gaps or within stands primarily composed of smaller, younger trees. Bats of both species frequently used torpor, with skin temperatures dropping below a torpor threshold on 89% of days (n = 72) and daily minimum skin temperatures averaging 16.5 {degrees}C over the course of our study. Average daily air temperature was a significant predictor of torpor use, with lower skin temperatures and more time spent in torpor observed on colder days. Minimum skin temperature and time spent torpid did not vary between bat species, nor did the characteristics of day-roosts. These data show that spring temperatures in Tierra del Fuego pose an energetic challenge that bats meet through frequent use of torpor, and likely, habitat selection. We recommend local conservation efforts keep these thermal challenges in mind by retaining large trees, which may provide warmer microclimates or room for social groups.

Bees play a key role in maintaining healthy terrestrial ecosystems by pollinating plants. Stingless bees (Apidae: Meliponini) are a diverse clade of social bees (>500 species) with a pantropical distribution spanning South and Central America, Africa, India, Australia and Asia. They are garnering increasing attention as commercially-beneficial pollinators of some crops, yet their contribution to the pollination of native plants in the tropics and subtropics remains poorly understood. Here we conduct a global review of the plants visited by stingless bees. We compile a database of reported associations (flower visits) between stingless bees and plants, from studies that have made either direct observations of foraging bees or analysed the pollen stored in nests. Worldwide, we find stingless bees have been reported to visit the flowers of plants from at least 220 different families and 1465 genera, with frequently reported interactions for many of the tropics most species-diverse plant families including Fabaceae, Asteraceae, Rubiaceae, Malvaceae, Lamiaceae, Arecaceae, Euphorbiaceae, Poaceae, Apocinaceae, Bignoniaceae, Melastomataceae and Myrtaceae. The list of commonly-visited plant families was similar for the stingless bee fauna of each of three major biogeographic regions (Neotropical, Afrotropical and Indo-Malayan-Australasian), though we detected differences in the proportional use of plant families by the stingless bees of the Indo-Malayan-Australasian and Neotropical regions, likely reflecting differences in the available flora of those regions. Stingless bees in all regions visit a range of exotic species in their preferred plant families (crops, ornamental plants and weeds), in addition to native plants. Although most reports of floral visitation on wild plants do not confirm effective pollen transfer, it is likely that stingless bees make at least some contribution to pollination for the majority of plants they visit. In all, our database supports the view that stingless bees play an important role in the ecosystems of the global tropics and subtropics as pollinators of an exceptionally large and diverse number of plants. This database also highlights important gaps in our knowledge of stingless bee resource use that may help focus future research efforts.

Apis laboriosa, the Himalayan giant honeybee, inhabits the foothills of the Himalaya and neighboring mountainous regions. Here we revise its distribution in light of recent reports and discoveries. The range now extends from longitude 105.9{degrees}E in Cao Bang, Vietnam, in the east to 74.4{degrees}E in the Pir Panjal Range of western Himalaya, a linear distance of 3300 km, with the most notable new localities in northeastern Vietnam, central Myanmar, northern Thailand, and AJK-Pakistan. The species generally occurs at lower elevations in the eastern part of its range than in Nepal, northern India, and the border region between India and Pakistan. Most but not all of the new localities are within the range predicted by species distribution modelling. We discuss the new localities that fall outside of the predicted range, the biotic characteristics of the terrestrial ecoregions in which the species occurs, and the remaining regions that may harbor this spectacular honey bee species.

Tropical island biodiversity is declining at alarming rates. Yet, understanding how species are coping with such disturbance is largely limited for afro-tropical islands. Here we examined habitat use and diel activity of insectivorous bats across different land-use types covering the endemic-rich Principe Island, Central West Africa. We acoustically surveyed insectivorous bats across 48 sites throughout old-growth forests, secondary re-growth forests, cocoa shaded plantations, and horticultures. Based on 17,527 bat-passes, we were able to record all four insectivorous bat species known to occur on Principe, including the recently described Pseudoromicia principis, the most frequently recorded species. Taphozous mauritianus, a data deficient open-space forager, was the least recorded species. Species activity was lowest in old-growth forests, as well as the activity of the edge-forager P. principis. The activity of the open-space forager Mops pumilus was lowest in forest habitats, whereas Hipposideros ruber, a forest forager, was restricted to these habitats. Diel activity patterns of M. pumilus varied between forests and non-forest habitats, whereas those of P. principis remained similar. Interspecific activity overlap decreased towards more altered land-use types. Our findings emphasize that conserving the remaining forests, along with the current mosaic of land-uses, is needed to maintain Principes complete insectivorous bat assemblages.

1Because Puerto Rico has warmed in recent decades, ectotherms there should have shifted their elevational ranges uphill. However, by comparing historical versus recent distributional records of Anolis lizards, we found that three \"montane-forest\" species have instead moved downhill in recent decades, almost to sea level. This downward shift appears related to the massive regeneration of Puerto Rican forests - especially in lowland areas - which started in the mid-20th century when the islands economy began shifting from agriculture to manufacturing. The magnitude of local cooling caused by regenerated forests swamps recent climate warming, seemingly enabling cool-adapted \"montane\" lizards to track forests as they spread downhill from mountain refugia into abandoned plantations. Thus, contemporary distributional patterns are likely converging to those prior to the arrival of European settlers, who cleared most lowland forests for agriculture, thereby restricting forests and associated fauna to high-elevation remnants. In contrast with the montane species, three lowland species expanded their ranges to higher elevations in recent decades; but whether this movement reflects warming, land-use shifts, or hurricane-induced destruction of upland forests is unclear.

Insect migrations rival those of vertebrates in terms of numbers of migrating individuals and even biomass, although instances of the former are comparatively poorly documented. This is especially true in the worlds tropics, which harbor the vast majority of Earths insect species. Understanding these mass movements is of critical and increasing importance as global climate and land use change accelerate and interact to alter the environmental cues that underlie migration, particularly in the tropics. Here, we provide the first evidence for an insect migration for the nymphalid butterfly Panacea prola in the Amazon, the worlds largest and most biodiverse rainforest that is experiencing a shifting climate and rapid forest loss.

BackgroundBumblebees are essential pollinators in many ecosystems. To maintain such ecosystem functions, bumblebee diversity remains an important concern. We measured abundance and diversity of bumblebee species along an elevational gradient over three flowering seasons. We hypothesized that co-occurring bumblebees partition niches over time and space. MethodsWe sampled bumblebees at six different meadows along Yulong Snow Mountain (Yunnan, SW China), a region known for high bumblebee diversity, over summer months (2017 - 2019). We analyzed the standardized abundances of the workers from different bumblebee species over 11 weeklong periods. We also analyzed the standardized abundances of the workers of each species at each of the six different meadows. ResultsClear patterns of temporal niche partitioning were most apparent for the two, dominant species, B. friseanus and B. lepidus. Spatial niche partitioning was evident for rarer species which tended to be most abundant at lower elevations. ConclusionsTemporal and spatial niche partitioning are among two of the ways that bumblebee diversity is maintained on Yulong Snow Mountain. This has future implications if changing climate conditions disrupt partitioning leading to increased interspecific competition.

Land-use intensification imposes selective pressures that systematically change the frequency of wild population phenotypes. Growing evidence is biased towards the comparison of populations from discrete categories of land uses, ignoring the role of landscape emerging properties on the phenotype selection of wild fauna. Across the largest urban-rural gradient of the Colombian Orinoquia, we measured ecomorphological traits of 216 individuals of the Flat-faced Fruit-eating Bat Artibeus planirostris, to evaluate the scale of effect at which landscape transformation better predicts changes in phenotype and abundance of an urban-tolerant species. Forest percentage at 1.25 km was the main predictor affecting abundance, wing aspect ratio, and body mass of this phyllostomid; but the direction of the effect differed between abundance and ecomorphological traits. Although landscape factors explained changes in the forearm length at all spatial scales, the effect was sex-dependent and the most important predictor was forest percentage at 0.5 km. Our results indicate that landscape elements and spatial scale interact to shape ecomorphological traits and the abundance of A. planirostris. Interestingly, the scale of effect was congruent among all biological responses. A pattern that likely arises since species abundance can reflect the variation on phenotype under different environmental filters across landscape scenarios.

Seasonal patterns in tropical insect communities remain poorly understood because temperature is rarely limiting to growth or reproduction in tropical climates. In these regions, insect seasonality is often attributed to rainfall, yet distinct seasonal dynamics also occur in ever-wet forests where climatic fluctuations are minimal. Here, we examine the seasonality of abundance and diversity in lepidopteran herbivores associated with the tropical tree genus Inga in Yasuni, an aseasonal lowland rainforest in the Ecuadorian Amazon. We find that both leaf production and herbivore communities show pronounced seasonal peaks during the driest and brightest months of the year. Using structural equation modeling, we evaluate the relative roles of climate and leaf production in shaping insect seasonality and find support for both pathways. Finally, we show that communities feeding on expanding versus mature leaves differ strongly in composition, with expanding leaves supporting more specialized and phylogenetically divergent herbivore assemblages. Together, these results demonstrate that even in an ever-wet tropical forest, subtle climatic cues and host phenology interact to drive pronounced insect seasonality

Oceanic islands, due to their evolutionary history and isolation, hold a disproportionately high proportion of endemic species. However, their evolutionary history also makes them vulnerable to extinctions, with most known extinctions occurring on islands. Plant-animal interactions are particularly important on islands, as island systems generally have low redundancy and are more vulnerable to disruption either via extinction or by invasive species. Here, we examined the fruit removal and seed predation of a keystone palm, Caryota mitis, on the remote oceanic island of Narcondam. The island endemic Narcondam hornbill (Rhyticeros narcondami), was the sole seed disperser of the Caryota mitis (90 hours; N = 15 trees), indicating a lack of redundancy in seed dispersal of the palm on this island. While the invasive rodent, Rattus cf. tiomanicus was the sole predator of the Caryota mitis seeds in the forest (N = 15 individual fruiting palms, 416 trap nights). Overall, 17.1% of the seeds placed (N = 375 seeds) were removed. Seeds placed under and away from the canopy, and at different densities (2 plots with 10 seeds each; 1 plot with 5 seeds, respectively), showed similar removal rates. This is indicative of ambient seed predation and the lack of safe sites for the regeneration of Caryota mitis, with potential deleterious effects on the subsequent stages of the "seed dispersal cycle". Here, from a data deficient site, we provide baseline information on the plant-frugivore interaction of a keystone palm and the potential impacts by an invasive rodent.

The Amazon hosts the worlds most diverse floodplain forests, characterized by tree communities adapted to seasonal flooding. In the estuary, these forests are driven by both fluvial and tidal dynamics, yet remain poorly studied. We assessed natural regeneration in a tidal white-water floodplain forest within the Fazendinha Environmental Protection Area, eastern Amazonia (Brazil). Regenerating individuals (DSH [≤] 5 cm) were sampled in 21 systematically distributed plots, classified into height classes, and analyzed with diversity indices, regeneration parameters, and ordination methods. We recorded 758 individuals from 43 taxa, 35 genera, and 20 families. Fabaceae was the richest and most abundant family, largely due to the oligarch Mora paraensis, which comprised >70% of individuals. Despite this dominance, Shannon diversity was high (H = 5.31), with 53.5% of species occurring as singletons or doubletons. Regeneration density reached 14,438 ind. ha{square}1, concentrated in the smallest classes, with few species spanning all classes. Subtle compositional shifts occurred with river distance, though dominants remained broadly distributed. Our findings highlight the resilience of oligarchic species and the vulnerability of rare taxa, advancing knowledge of estuarine floodplain ecology and providing essential baseline information for conservation and management in this understudied region.

Abiotic and biotic factors are known to be key in limiting the geographical distribution of species. However, our understanding on the influence of habitat heterogeneity on ecological interactions and behavior in tropical animals is limited. We studied groups of Acorn Woodpeckers (Melanerpes formicivorus flavigula) in urban and rural areas in northern South America to understand how habitat and resource requirements (food storage structures) influences patterns of distribution across the Aburra Valley, in the northern area of the Central Andes of Colombia. Using focal observations of 10 different groups over nearly a two-year period, we estimated territory size, habitat use, and described the use and presence of granaries. We found that territory size, tree diversity, and the use of granaries varied among groups. Accordingly, Acorn Woodpeckers use a wide variety of tree species to make cavities, to feed and to build granaries for social interactions. Our study supports the hypothesis that Acorn Woodpeckers do not rely on the Colombian Oak (Quercus humboldtii Bonpl.) for feeding, nesting or foraging in the Aburra Valley, and that the construction of granaries to store food is present in urban populations, despite the lack of strong seasonal changes in tropical areas. We suggest that the distribution of the Acorn Woodpecker in our study area is strongly associated with one particular species of tree, Albizia carbonaria Britton, and the behavior of granaries construction might be hardwired in this species for the maintenance and cohesion of family groups.

We tested if gouging by Callithrix jacchus affects tree survival. The proportion of dead gouged trees in forest fragments was higher than the proportion of dead non-gouged trees, with larger effect on smaller trees. The number of holes did not affect tree survival. Parasitism of trees by marmosets may enhance forest turnover.

The Caqueta titi monkey (Plecturocebus caquetensis) is Critically Endangered (CR) due to habitat destruction associated with extensive livestock ranching and farming. But unfortunately, information on the ecology and behavior of the species is scarce. Here we describe seasonal behavioral patterns and home range size of P. caquetensis in a 23-ha forest fragment in Colombia. In 2013, we collected focal animal behavioral data of a group of seven individuals of P. caquetensis. Overall, titi monkeys spent 33% of their time feeding, 4% locomotion, 42% resting, and 21% engaging in social interactions, such as grooming and vocalizations. However, the activity budgets differed substantially between seasons. In the dry season titi monkeys invested significantly more time feeding than in the rainy season, when they spent more time moving. They invested a similar amount of time in social interactions in both seasons. Home range size was larger during the rainy season; but the core areas of the home ranges had a similar size and they overlapped across seasons, suggesting the overall importance of this area for titi monkeys. These findings constitute the first study on the seasonal ecology and home range of this Critically Endangered species, and it identifies a priority local conservation area.

Stingless bees are key pollinators in tropical ecosystems, yet their ecological dynamics remain poorly understood in highly seasonal environments such as the seasonally dry tropical forests of Ecuador. These ecosystems experience pronounced climatic seasonality, with sharp transitions between dry and wet periods that strongly affect floral resource availability. Understanding interspecific competition and niche partitioning in such systems is critical, particularly given the global decline of pollinators. We investigated resource use and niche dynamics in two native stingless bees, Melipona mimetica and Scaptotrigona sp., by quantifying pollen, nectar, and resin collection across seasons. Log-linear models were used to test the effects of species, season, and their interaction on resource use, while non-metric multidimensional scaling (NMDS) assessed niche overlap. Contrary to the expectation that niche overlap increases under resource scarcity, we found greater overlap during the wet season, when resources are more abundant. This suggests that both species converge on high-quality floral resources during peak availability, reflecting an adaptive response to strong environmental seasonality. Pollen use remained stable across seasons, consistent with generalist foraging behavior. In contrast, nectar collection increased significantly during the wet season, while resin exhibited a shared seasonal peak, likely associated with synchronized nest construction or maintenance. These findings reveal context-dependent competition dynamics and highlight the role of environmental seasonality in shaping pollinator interactions. Our study provides new insights into the ecology of threatened stingless bees and contributes to their conservation in tropical dry forest ecosystems.

Plant species richness is influenced by complex interactions between biotic and abiotic factors that operate on different spatial scales. Since spatial scales vary continuously in nature, it is expected that multiple factors simultaneously affect species richness and composition at an intermediate spatial scale (i.e., the mesoscale landscape level). Previous studies have shown that local topography and elevation are important factors for shaping mesoscale landscape-level plant species richness; however, the relative importance of these factors has rarely been examined. Here, we used spatially explicit woody plant survey data to investigate the relative importance of topography, elevation, and disturbance at the mesoscale landscape level. We found that topography and elevation are important drivers of plant species richness and composition at the mesoscale landscape level and affect different components (i.e., the number of species and species composition, respectively). Our study also found that closely-related species coexisted along the elevational gradient, suggesting that niche partitioning among closely-related species is a fundamentally important feature of mesoscale species richness pattern. Furthermore, we found that specialization in a habitat of closely-related species can be established even within a limited environmental gradient. This suggests that biotic interactions among closely-related species may be an important factor driving habitat specialization, and biotic interactions may play an important role in shaping landscape-scale biodiversity patterns.

According to the acoustic adaptation hypothesis, environmental and biogeographic factors such as atmospheric humidity can influence divergence of acoustic signals and speciation in high duty-cycle echolocating bats (e.g. Rhinolophus sp.), although this remains disputed. In this study we tested the hypothesis that Resting Frequency (RF) would decrease with increasing humidity along a large latitudinal gradient (6{degrees}-21{degrees} N), for four Rhinolophus species with different evolutionary histories, in the Western Ghats-Sri Lanka (WGSL) region. We conducted acoustic recordings and compiled published information on RFs of stationary Rhinolophus indorouxi, R. rouxi, R. beddomei, and R. lepidus from 40 roosts in 18 localities of the WGSL. These data comprised of recordings made with different devices and with different settings. Hence, due to the unknown measurement error involved in the recorded RFs, it was not possible to conduct conventional regression analyses to test our hypotheses. Hence, we qualitatively assessed effects of Relative Humidity (RH) and other environmental variables by interpreting only the sign, but not the magnitude of the RF responses (from the slopes of generalized least squares regression models). We also tested how RF and RH varied across biogeographic zones, and with bat body size. RFs of the Miocene-diverged species R. indorouxi and R. rouxi were higher at lower RH, as expected. In contrast, RF of the Pleistocene-diverged species R. beddomei and R. lepidus were higher at higher RH. Elevation and rainfall also emerged as important predictors of RF variation in these species. Bat body size differed in dry and humid regions of the WGSL. RF variation was not consistent across biogeographic zones. The cryptic, phonically differentiated sibling species R. indorouxi and R. rouxi co-occurred only in mid-elevation zones along the Western Ghats escarpment. The variable but significant influences of humidity and correlated factors on RF suggest the importance of environmentally mediated acoustic divergence in different Rhinolophus species in the WGSL. We propose some hypotheses on interacting effects of environmental and phylogenetic factors on acoustic divergence in Rhinolophus bats of the WGSL. These ideas could be further tested with phylogenetic and acoustic studies, as more consistent and comparable data on these species become available in the future.

Giant trees in the Amazon play crucial ecological roles by acting as substantial carbon sinks and supporting diverse forest ecosystems. However, these emergent trees are increasingly vulnerable to climatic changes, and recent research suggests that the distribution and niche of many emergent species are severely threatened. This study employs ecological niche modeling using data LiDAR and forest inventory, global repository data, and bioclimatic variables to project the potential larger tree distributions under past, current, and future climate scenarios (SSP1-2.6 and SSP5-8.5) in different biogeographic provinces in the Amazon basin. We used algorithms MARS, RandomForest, MaxEnt, and GAM to assess the impact of critical climatic factors, including isothermality, maximum temperatures, and precipitation patterns, on the habitat suitability of these larger trees and species Dinizia excelsa and Goupia glabra. Our results show that the tall trees dataset, Dinizia excelsa and Goupia glabra exhibit congruent distinct responses to climate variables, with Dinizia excelsa being more sensitive to increased temperature extremes, particularly in the Guiana Shield and Roraima Provinces. In contrast, Goupia glabra displays a broader tolerance to precipitation variability. Under the high-emission scenario (SSP5-8.5), both species are projected to lose up to 45% of their suitable habitats by 2080, primarily in southern Amazon provinces like Xingu-Tapajos, where increased drought frequency and temperature extremes are expected. Conversely, the low-emission scenario (SSP1-2.6) suggests potential habitat stability or even slight expansions in the northern Amazon regions due to moderate temperature and rainfall conditions. These findings highlight the urgent need for conservation strategies to protect critical refugia and enhance ecosystem resilience. By integrating niche modeling with climate projections, our study provides vital insights into managing Amazonian giant trees, emphasizing their potential role in mitigating global climate change impacts.

The present note intends to challenge, based on field observations, the definition of treeline and argues for considering the upper occurrences of tree-species as an integrative result of historical and contemporary processes acting on high-altitude socio-ecosystems. A field survey of Pinus cembra growing above 2800 m asl was conducted, in an ecoregion of southwestern Alps, straddling France and Italy (Queyras-Mt Viso area). Pines were described (height, density) and their habitats were contextualized (altitude, slope degree and exposure, bedrock). Individuals of Pinus cembra are commonly growing between 2800 and 3200 m asl, generally on east-facing, steep and rocky slopes, with a pine density decreasing with altitude. Pines are generally dwarf-shaped, sometimes erected or prostrated. Their needles are half the size compared to those of pines growing in subalpine forests. Pine morphology indicates harsh growing conditions, notably strong wind, aridity and frost. These habitats constitute visually emerging objects attractive for the nutcracker caching behaviour. This setting acts as a positive passive driver for pine at high altitudes, which is further favoured by intense atmospheric moisture supplied by the east from the Po valley. Steep and rocky slopes exclude livestock, likely explaining why these pines are located in grass-less habitats. These tree clusters constitute remarkable "sky-island" populations. Larix decidua and Pinus uncinata were also recorded at exceptional altitudes but P. cembra is the most frequent species in high alpine conditions. These observations altogether highlight a complex pattern of tree-species line in the western Alps, and probably beyond.

In a bird-flowering plant network, birds select plants that present traits attractive to them. I studied plant characteristics that might predict flower visitation rate by the most common bird visitors in a bird-flowering plant network located in an elfin forest of the Andes. The nectarivorous birds which had the highest number of interactions with flowering plants in this network were the Coppery Metaltail (Metallura theresiae), the Great Sapphirewing (Pterophanes cyanopterus), and the Moustached Flowerpiercer (Diglossa mystacalis). I analyzed different flower traits (flower aggregation, nectar volume, nectar energy, color, orientation, and dimensions of the corolla) of the common plants that these birds visited with a principal component analysis. The plants most visited by birds were Brachyotum lutescens and Tristerix longebracteatus. While nectar traits of the plants seemed to be the best predictor for bird visitation, there was no statistical association between visitation and plant traits, except for Metallura theresiae in the dry season. I discuss the possible causes of resource partitioning for these nectarivorous birds.