Anthropogenic disturbances pose significant challenges for wildlife conservation, especially for threatened primates such as the mantled howler monkey (Alouatta palliata). We investigated whether and how human presence and noise influence the immediate movement responses of mantled howler monkeys inhabiting an agroforestry system in Los Tuxtlas, Mexico. Between January 2020 and April 2021, we recorded monkey and human locations, human activities, and A-weighted equivalent continuous sound pressure levels (LAeq) at 15-min intervals during 823 h of observation. Using generalized linear mixed models, we found that both the occurrence and magnitude of avoidance movement increased significantly with increasing worker numbers and sound pressure levels. Although movement increased throughout the day, movement direction relative to human location remained constant, suggesting that circadian patterns influence when, but not how animals respond to anthropogenic factors. Therefore, howler monkeys avoid human presence while maintaining their characteristic energy-conservative ranging patterns, suggesting a complex balance between risk avoidance and metabolic demands. Our findings have important implications for wildlife management in agroforestry systems, as even relatively low levels of human presence (approximately one person per hectare) and noise (ranging from 40 to 85 dB) can trigger behavioral responses.

Modifying decisions depends on the cost of change, especially in sit‐and‐wait predators. Once situated, and before prey arrival, they should remain immobile because any changes in their position inside the pit can disturb their traps or alert prey and predators. Antlion larvae ( Myrmeleon spp.) dig conical pits in the soil to capture walking arthropods, often ants. The larva then ejects the prey carcass using its mandible as a catapult. Therefore, its orientation in the pit determines the direction of expelling debris. We tested the hypothesis that antlion larvae orient themselves at the bottom of their pits to avoid future movements and that they decide their position based on environmental features such as the proximity of vertical obstacles and the ground's slope. In the field, we dropped standardized debris into pits located near and far from walls and recorded the direction of their expulsion. The expelled debris direction was consistent as larvae maintained their position at the bottom of their pit throughout time, and their position was independent of the pit's distance from a wall. In the lab, we induced larvae to build pits in narrow and sloped terraria. Larvae oriented themselves to avoid expelling objects towards a wall or uphill, preventing them from bouncing off or rolling back into the pit. These results suggest that during trap‐building, larvae use environmental information to decide how to position themselves at the bottom of the pit to avoid posterior movements. Our findings emphasize the importance of gathering accurate environmental data to avoid position shifts before prey arrival, which can reduce the capture efficiency of sit‐and‐wait predators.

Emerging evidence shows that responses to deforestation can differ both across species and among populations of the same species. The reasons underlying these complex patterns are unclear, and this lack of clarity is a barrier to accurate monitoring and prediction of biodiversity change. Using data from 2,262 bird species across 7,326 sites from all forested continents, we show that between-species and within-species variations in responses to forest cover are mediated by temperature. Populations in warmer macroclimates tend to decline in incidence in deforested landscapes because hotter microclimates push them closer to their species' realized upper thermal tolerance limits. By contrast, populations in cooler macroclimates tend to be less affected by or even benefit from deforestation, as microclimatic temperatures are pushed closer to more optimal temperatures. Our findings offer an empirically grounded framework for biodiversity models that move beyond fixed species responses and incorporate interactions between temperature and land-use change.

Understanding the main factors determining the maintenance of native species in agroecosystems is of great importance to promote biodiversity-friendly practices. Here, we assessed the individual and interactive effect of local (management intensity, tree basal area, and tree diversity) and landscape (forest cover) predictors on the diversity of bees and social wasps in shaded cocoa agroforests located in the Brazilian Atlantic Forest. Using Malaise and attractant traps to survey these insects on 29 agroforests, we revealed that bee species number was positively associated only with forest cover, whereas tree diversity influenced bee species composition. In contrast, wasp species number enhanced with increasing management intensity, but only in agroforests inserted in landscapes with low forest cover, while no variable influenced the composition of social wasp species. These results reinforce the greater tolerance and ecological plasticity of social wasps, which can benefit from intensified management in structurally complex systems such as shaded agroforests. Nevertheless, bees tend to be more sensitive and dependent on forest cover at the landscape scale. Therefore, restoration efforts to increase forest cover in more deforested landscapes are urgently needed to ensure the high conservation value of shaded cocoa agroforests, especially for bee assemblages.

Understanding the effects of landscape-scale forest loss on the regenerative potential of tropical rainforests-measured through the abundance, species diversity, and composition of infant and juvenile trees-is essential for biodiversity conservation in human-modified landscapes. However, this topic remains poorly understood, particularly with regard to ecological thresholds, i.e., levels of forest cover below which regenerative potential may collapse. We sampled infant (<130 cm in height), juvenile (>= 130 cm height and <10 cm DBH), and adult (>= 10 cm DBH) trees across fourteen 1-km2 landscapes spanning a gradient of similar to 0 to 100% forest cover in a biodiverse tropical rainforest region of southeastern Mexico. We assessed the impact of forest loss on tree density, species diversity, compositional integrity-defined as the proportion of species shared between fully forested and increasingly deforested landscapes-for each life stage, and compositional differences between them. All community attributes declined with forest loss across life stages, with more pronounced decreases in highly degraded landscapes. Our results indicate that maintaining more than 30% forest cover is critical to preserving the forest's regenerative potential. Below this threshold, assemblage density and species composition in regenerating communities sharply decline and begin to diverge from adult assemblages. These findings underscore the importance of incorporating forest cover thresholds into conservation strategies in human-modified tropical rainforest landscapes.

Fire has been a fundamental tool for human evolution and well-being. In slash-and-burn agriculture (SBA), it has been used for millennia to eliminate field debris, accelerate the incorporation of nutrients into the soil, and control weeds. However, in addition to these desired outcomes, fire can have multiple undesired environmental impacts that threaten the sustainability of tropical forests and SBA itself. We hypothesized that the environmental costs of fire use in SBA can outweigh its agronomic benefits across tropical forests. To assess this hypothesis, we critically reviewed empirical evidence on both desired and undesired environmental effects of SBA-related fire across the tropics worldwide. We found that fire effectively facilitates land clearing and releases nutrient-rich ashes that temporarily fertilize the soil. However, this fertilization is short-lived and restricted to the topsoil, while a substantial fraction of forest nutrients is wasted through volatilization and post-fire erosion. SBA-related carbon emissions may also contribute to climate forcing at regional and global scales. Although fire can reduce weed pressure by damaging seeds and limiting seed bank viability, this recruitment limitation can delay or arrest secondary succession, thereby constraining forest recovery and its ability to offset fire damage in SBA-dominated landscapes. In addition, repeated burning increases the risk of accidental wildfires, amplifying forest loss and associated biodiversity loss and carbon emissions. Elevated soil temperatures during burning can negatively impact soil biota, disrupting their essential ecological functions. Overall, despite notable remaining knowledge gaps, our review suggests that the environmental costs of using fire in SBA outweigh its benefits.

The species-area relationship (SAR) has long been used to predict extirpation rates from habitat loss, but these rates depend not only on habitat area but also on the surrounding landscape and species' habitat specialization. We collated global data from forest islands created by river damming and forest fragments resulting from clear-cut deforestation to examine the effects of matrix type (aquatic or terrestrial) and tree cover on avian SARs. Unlike oceanic islands, which are often millions of years old, anthropogenic forest islands provide a contemporary analog to forest fragments to understand matrix effects on SARs and serve as a baseline for worst-case scenarios of forest fragmentation. Our database comprises 50 datasets from 45 studies conducted in tropical and subtropical regions, totaling 1,954 bird species detected through 39,197 incidence records from 336 forest islands and 669 forest fragments. We found that bird extirpation rates were lower in fragments than on islands, especially for forest-dependent species compared to all species. Species losses were further reduced by increasing tree cover around forest remnants at local landscape scales of 300 m, highlighting the importance of small-scale conservation strategies. Moreover, even small forest fragments with greater nearby tree cover held high conservation value, emphasizing the crucial role of the surrounding landscape in mitigating avian extirpations from forest remnants. Beyond protecting forest remnants themselves, area-based conservation efforts would therefore be greatly enhanced by improving matrix quality and expanding tree cover in otherwise hostile landscapes.

Given the ongoing global pollinator crisis, understanding how land-use change affects pollinator insects, such as euglossine bees, has never been more important. This information can be used to promote biodiversity conservation and sustain food production in agricultural landscapes, such as those exposed to slash-and-burn agriculture (SBA) – a traditional farming system that is expanding worldwide. As SBA creates heterogeneous landscape mosaics of different land uses, we used a site-landscape design to assess the relative importance of four dominant land uses (old-growth forest, secondary forest, burned land, and agricultural land) and two landscape structure variables (old-growth forest cover and land-use diversity) for preserving euglossine assemblages in the Mayan forest, Mexico. We captured bees in 20 sites (5 sites/land-use type) and estimated bee abundance and species richness in each site. Contrary to our hypothesis, bee abundance was between 2x and 3x higher in open areas (burned and agricultural lands) than in old-growth and secondary forests, and increased in more deforested landscapes. However, bee abundance was not related to land-use diversity, and species richness was independent of land-use type and landscape structure variables. These findings indicate that open areas contribute to the preservation of euglossine bees in SBA landscapes of the Mayan forest. However, this contribution is likely related to the maintenance of high forest cover in the region, where open areas are still small and close to the forest – optimal landscape scenarios for forest species, especially for euglossine bees, which are highly mobile and can find many supplementary resources in open areas.

Tropical forests and their fauna are being lost at alarming rates, causing important cascading effects that can limit ecosystem functioning. A significant cascading effect relates to dung beetles, which depend on forests and the excrement of terrestrial mammals for feeding and reproduction, making them particularly vulnerable to both deforestation and defaunation. While recent studies have explored the influence of forest structure and mammal activity on dung beetle communities in fragmented landscapes, to our knowledge, no study to date has simultaneously tested the combined effects of deforestation and defaunation on dung beetle species richness and body mass across a continuous landscape–scale gradient of forest loss. We assessed whether and how species richness and body mass of dung beetles relate to deforestation and defaunation across 18 1–km2 landscapes in a Mesoamerican biodiversity hotspot. Our results indicated that landscape–scale species richness and body mass of dung beetles decrease in more deforested and defaunated landscapes. Indeed, such a decrease in species richness accelerated in landscapes with < 40

Different regions of the tropics vary in overall tree species diversity, with the tropical Americas exhibiting strikingly higher regional tree species richness than Africa and Southeast Asia. We investigated whether these differences also occur at the local scale and whether the environmental conditions associated with tree species richness are consistent across tropical regions despite highly dissimilar species pools. A spatial random forest model was trained by using a network of 429 1-hectare plots across the tropics, together with 24 environmental variables, to predict plot-level tree α diversity. A combination of climatic, soil and topographical variables explained ∼86% of the variation in richness. Despite differences in regional species pools and the potentially disruptive effects of different geological, climatic and evolutionary histories, the relationship between environmental variables and local-scale tree species richness is closely similar across different continents. Our findings imply a pervasive role of niche-based mechanisms in structuring local tree species richness, regardless of the regional species assemblages. This pantropical convergence in the richness-environment relationship poses a challenge for ecology to explain.

Understanding the effects of forest loss and fragmentation per se (independent of forest loss) on wildlife is urgently needed to design biodiversity-friendly landscape scenarios, particularly for forest-specialist species, such as many ground and arboreal tropical mammals. As this topic remains contentious, we assessed the species-specific response of 14 arboreal and ground mammals to landscape-scale forest loss and fragmentation measured across different scales in the Lacandon rainforest, Mexico. Surprisingly, most species (6 of 14 species, 43

ABSTRACT Motivation The accelerated and widespread conversion of once continuous ecosystems into fragmented landscapes has driven ecological research to understand the response of biodiversity to local (fragment size) and landscape (forest cover and fragmentation) changes. This information has important theoretical and applied implications, but is still far from complete. We compiled the most comprehensive and updated database to investigate how these local and landscape changes determine species composition, abundance and trait diversity of multiple taxonomic groups in forest fragments across the globe. Main Types of Variables Contained We gathered data for 1472 forest fragments, providing information on the abundance and composition of 9154 species belonging to vertebrates, invertebrates, and plants. For 2703 of these species, we obtained more than 20 functional traits. We provided the spatial location and size of each fragment and metrics of landscape composition and configuration. Spatial Location and Grain The dataset includes 1472 forest fragments sampled in 121 studies from all continents except Antarctica. Most datasets (77%) are from tropical regions, 17% are from temperate regions, and 6% are from subtropical regions. Species abundance and composition were collected at the plot or fragment scale, whereas the landscape metrics were extracted with buffer size ranging from a radius of 200–2000 m. Time Period and Grain Data on the abundance of species and community composition were collected between 1994 and 2022, and the landscape metrics were extracted from the same year that a given study collected the abundance and composition data. Major Taxa and Level of Measurement The studied organisms included invertebrates (Arachnida, Insecta and Gastropoda; 41% of the datasets), vertebrates (Amphibia, Squamata, Aves and Mammalia; 44%), and vascular plants (19%), and the lowest level of identification was species or morphospecies. Software Format The dataset and code can be downloaded on Zenodo or GitHub.

The ongoing deforestation process across the globe is reducing the extent of suitable habitat for forest-specialist species. The cross-habitat spillover hypothesis posits that in such a scenario, some species may be compelled to use supplementary resources from the adjacent anthropogenic matrix. Consequently, the compositional differentiation (beta diversity) between forest remnants and the matrix should decrease (i.e. biotic homogenization) in more deforested landscapes. We tested this prediction by assessing bird assemblages in a mountain region of Guerrero, Mexico. We surveyed birds in nine landscapes with different forest cover. Within each landscape, we measured bird beta diversity (D β ) between forest fragments and the surrounding anthropogenic matrix and then assessed the relationship between D β and landscape forest cover. We separately assessed the complete bird assemblage, and forest-specialist and habitat-generalist birds, because the cross-habitat spillover hypothesis posits that the loss of D β in more deforested landscapes should be particularly evident when assessing forest-dependent birds. The generalized linear models indicated that, as expected, D β decreased in landscapes with lower forest cover. Such a decrease was significant when assessing the complete bird assemblage and forest-specialist birds, but not when assessing habitat-generalist species. Our findings support the cross-habitat spillover hypothesis and indicate that forest loss contributes to the homogenization of bird assemblages in human-modified landscapes. Such homogenization process could also be related to an alternative but non-exclusive mechanism: the extirpation of rare, non-ubiquitous forest-specialist species in more deforested landscapes. To conserve bird assemblages in human-modified landscapes, we should prevent forest loss and promote adequate management strategies (e.g. leaving standing native trees, avoiding hunting, and removing feral predators) to prevent threats to forest-specialist species when they use the matrix.

Understanding habitat fragmentation effects on wildlife is critical to promoting effective conservation practices. There are many metrics of habitat fragmentation, from simple (number of habitat patches) to complex metrics designed to summarize many aspects of landscape patterns. To make meaningful inferences, we must understand how complex metrics are related to landscape patterns, especially to habitat amount. Here, we examine the behavior of the Edge Influence index, a metric that has been used in several influential recent studies and is designed to assess fragmentation and edge effects. Contrary to expectation, this index does not primarily quantify fragmentation or edge but rather habitat amount. Therefore, researchers should take this into consideration when interpreting the results of studies based on the Edge Influence index. To guide meaningful conservation action in fragmented landscapes, we recommend using simple, direct measures of fragmentation and separating the effects of habitat configuration from the effects of habitat amount.

Aim: Land-use change is a major threat to biodiversity, yet there remains considerable unexplained variation in how it affects different populations of the same species. Here, we examine how sensitivity to forest cover changes depending on proximity to different limits of a species' range. By comparing responses as species approach their coastal ('hard') and inland ('soft') range limits, we aim to provide insight into the relative influence of mass effects, as compared to abiotic and biotic environmental suitability in shaping population sensitivity. Location: Global. Time Period: 1996-2019. Major Taxa Studied: Birds. Methods: We combined data from several large databases to obtain a dataset of 2543 bird species surveyed across 116 studies, spanning six continents. Using expert-verified range maps, we calculated the position of populations relative to their species' nearest inland ('soft') and coastal ('hard') range limits and categorised the inland limits as equatorward- or poleward- facing. We investigated how distance to range limits and forest cover, derived from a 30 m-resolution global dataset, affect the probability of species' incidence. Results: We found that bird populations are more sensitive to forest cover when located closer to their species' inland ('soft') range limits, whereas this was not the case at coastal ('hard') range limits. The heightened sensitivity to forest cover at soft range limits was similar regardless of whether the range limit faced equatorward or poleward. Main Conclusions: These results highlight how populations close to the soft limits of their species' ranges are at higher risk of extirpation resulting from loss of forest cover. This suggests that environmental conditions (e.g., climate), which become more challenging away from the core of the species' range, drive variability in sensitivity to forest cover.

Land-use changes are rapidly transforming tropical forests into heterogeneous landscape mosaics with different anthropogenic land covers, leading to species loss and the disruption of their ecological functions. While the impact of landscape composition on taxonomic diversity is well documented, its influence on functional diversity remains poorly understood. This is particularly relevant for species like bats and rodents, which play essential ecological roles in both natural and human-modified ecosystems. To address this knowledge gap, we used a multi-model inference approach to assess the influence of landscape composition metrics measured across seven spatial scales on bat and small rodent diversity in the Yucatan peninsula, a highly deforested biodiversity hot-spot. Our findings indicate that urban cover is the main factor negatively impacting the taxonomic and functional diversity of both taxa. Urban expansion impacts on small rodents were related to their limited dispersal capacity and small home ranges and the high dependence of arboreal rodents on forested habitats. Forest cover was mainly related to bat functional diversity, positively affecting forest-specialist species. Therefore, landscape modification, especially urbanization, threaten bat and rodent diversity even in landscapes with higher forest cover, highlighting the importance of assessing both taxonomic and functional diversity to develop effective conservation strategies in human-modified landscapes. Management strategies are needed to mitigate these negative impacts, including maintaining forest remnants and increasing overall forest cover. The persistence of bat and rodent assemblages are essential for the health and resilience of forest ecosystems, as they provide crucial functions such as herbivory, predation, seed dispersal and pollination.

Slash-and-burn agriculture creates heterogeneous landscapes composed of old-growth forests, secondary forests, and agricultural lands. In these mosaics, some species are extirpated (loser species) and replaced by disturbance-adapted species (winners). However, the community-level outcome of this winner–loser species replacement and its local and landscape drivers remain poorly understood. We assessed the effect of local land-use type and the surrounding old-growth forest cover on small rodent populations and communities in landscape mosaics exposed to slash-and-burn agriculture. We hypothesized that winner–loser species replacements may contribute to maintaining or increasing rodent diversity. Using Sherman traps, we sampled small rodents in 14 sites (5 old-growth forests, 5 secondary forests, and 4 agricultural lands) from the Mayan forest, Mexico. We then evaluated the effect of land-use type and landscape forest cover on species-specific abundance, total abundance, and species richness. We recorded 428 rodents from 6 native species and one exotic (Rattus rattus). Total abundance was weakly related to both predictors. Yet, one species (Ototylomys phyllotis) decreased in abundance in agricultural lands (loser species), and three species (Heteromys gaumeri, Peromyscus yucatanicus, and Sigmodon toltecus) followed the opposite pattern (winner species), which increased species richness in agricultural lands. The abundance of Heteromys gaumeri and Peromyscus leucopus also increased with old-growth forest loss, increasing species richness in more deforested landscapes. Our findings indicate that slash-and-burn agriculture promotes winner–loser species replacements, which maintain rodent abundance, but increase species richness. However, to prevent the extirpation of forest-dependent species, we must preserve old-growth forests.

1. Understanding why animals avoid some locations is needed to improve the theory of habitat selection. This is key in semi-sedentary organisms, such as antlion larvae, because once established they rarely move, and their performance largely depends on local environmental conditions.2. Antlion larvae are sit-and-wait predators that build conical pitfall traps in sandy soils to capture passing prey. They clean constantly their traps, expelling soil, prey carcasses and debris out of the pit to maintain their trapping success. Therefore, we propose that they avoid soils with leaf litter because leaves hinder the maintenance of their pits; a hypothesis that has not yet been tested.3.We first demonstrated that antlion larvae (Myrmeleon inmaculatus) are rare from soils with leaf litter in a tropical semi-deciduous forest in Mexico. We then experimentally tested the effect of leaf litter on pit maintenance by adding debris in 90 antlion traps, 45 of which were covered with a leaf, and 45 remained uncovered. Two hours after adding the debris, we recorded its location and quantified the variation in depth and diameter of the pits. 4. 4.Larvae in uncovered traps were twice as effective at cleaning up the debris than larvae in covered traps. Furthermore, in just 2 h, covered traps were on average 21% shallower than control traps, probably because unsuccessful attempts to clean debris caused sand slides to fill the pit partially.5.Leaf litter seems to hinder the proper maintenance of antlion traps, explaining at least partially, why these animals are rare under leaf litter.

Tropical tree species are increasingly being pushed to inhabit deforested landscapes. The habitat amount hypothesis posits that, in remaining forest patches, species diversity in equal-sized samples decreases with decreasing forest cover in the surrounding landscape. We tested this prediction by taking into account three important factors that can affect species responses to forest loss. First, forest loss effects can be linear (proportional) or nonlinear, as there can be threshold values of forest loss beyond which species extirpation may be accelerated. Second, such effects are usually scale dependent and may go unnoticed if assessed at suboptimal scales. Finally, species extirpation may take decades to become evident, so the effects of forest loss can be undetected when assessing long-lived organisms, like adult old-growth forest trees. Here, we evaluated the linear and nonlinear effects of landscape forest loss across different spatial scales on site-scale abundance and diversity of old-growth forest trees, separately for four plant-life stages (seeds, saplings, juveniles, and adults) in two rainforest regions with different levels of deforestation. We expected stronger (and negative) forest loss effects on early plant-life stages, especially in the region with the highest deforestation. Surprisingly, in 13 of 16 study cases (2 responses × 4 life stages × 2 regions), null models showed higher empirical support than linear and nonlinear models at any scale. Therefore, the species richness and abundance of local tree assemblages seem to be weakly affected by landscape-scale forest loss independently of the spatial scale, life stage, and region. Yet, as expected, the predictive power of forest cover was relatively lower in the least deforested region. Our findings suggest that landscape-scale forest loss is poorly related to site-scale processes, such as seed dispersal and seedling recruitment, or, at least, such effects are too small to shape the abundance and diversity of tree assemblages within forest patches. Therefore, our findings do not support the most important prediction of the habitat amount hypothesis but imply that, on a per-area basis, a unit of habitat (forest) in a highly deforested landscape has a conservation value similar to that of a more forested one, particularly in moderately deforested rainforests.