Biology subjects

Naniwadekar, R.

Publications and source records attributed to Naniwadekar, R..

At least 19 recordsLinked to original sources

bioRxiv2026

More fruits, more frugivores, but not necessarily more visits: findings from two tropical plant-avian frugivore communities

Fruit resource availability can influence the local abundance of avian frugivores through bottom-up regulation, but whether greater resource availability translates into higher visitation rates to fruiting trees remains poorly understood. Greater fruit availability could increase visitation by supporting larger frugivore populations, or reduce visitation to individual trees if increases in frugivore abundance are not proportionate to those in fruit availability or if frugivores distribute their foraging effort. Understanding these relationships can provide insights into the relative role of abundance and trait-based mechanisms in structuring plant-frugivore communities. We compared fruit availability, avian frugivore abundance, and frugivore visitation rates on fruiting trees across two protected wet tropical forest sites: Anamalai Tiger Reserve in the Western Ghats and Namdapha Tiger Reserve in the Eastern Himalaya. Specifically, we quantified the availability of bird-consumed fruits across one-ha patches, estimated local abundances of major frugivore groups, and tested whether visitation rates on individual fruiting trees were related to frugivore abundance, body mass, and degree of frugivory. We found that small-seeded fruit availability was significantly higher in Anamalai than in Namdapha. Local abundances of several relatively small-bodied frugivore groups, including bulbuls, barbets, fairy-bluebirds, and mynas, were also higher in Anamalai. However, visitation rates of several frugivore groups on individual fruiting trees were higher in Namdapha. Visitation rates across all avian frugivore species were associated with frugivore abundances only in Anamalai, and not associated with body mass or degree of frugivory in either site. Thus, although greater fruit availability was likely associated with higher frugivore abundance, this increase in abundance did not consistently translate into higher visitation rates at individual fruiting trees, which provides some support for the resource dilution hypothesis. Our results highlight the importance of considering fruit resource availability and frugivore abundance when examining variation in tropical plant-frugivore interactions.

ecology↗

bioRxiv2026

Phenological Plasticity without Directional Change: Tropical Hornbills Track Temperature but Maintain Reproductive Stability

Climate change is altering breeding phenology in birds worldwide, yet tropical systems remain understudied despite harbouring the greatest avian diversity. We drew upon 26 years (1998-2024) of breeding phenology and reproductive success data on three sympatric Asian hornbill species (Great Hornbill Buceros bicornis, Wreathed Hornbill Rhyticeros undulatus, Oriental Pied Hornbill Anthracoceros albirostris) from a tropical forest in northeast India to examine whether trends in long-term breeding parameters reflect directional climate change or interannual variability. Over the study period, we found no significant directional trends in nest entry timing, occupancy, or breeding success over 26 years, despite modest regional warming. However, breeding parameters showed sensitivity to interannual temperature variation, with pre-breeding temperature (January-February) explaining 36-70% of variance in nest timing. Temperature sensitivity differed among species, with Wreathed Hornbill showing the strongest response (-15.9 days/{degrees}C), followed by Great Hornbill (-9.8 days/{degrees}C), and Oriental Pied Hornbill showing the weakest (-4.8 days/{degrees}C), consistent with predictions that larger, frugivorous species with extended breeding cycles would exhibit greater climatic sensitivity. The underlying mechanism appears related to a body size-phenology-thermal exposure interaction: Oriental Pied Hornbills nest later (mid-April) with shorter breeding cycles ([~]90 days), completing reproduction before peak monsoon heat (June), whereas both larger species nest earlier (mid-February) but endure thermal stress throughout extended breeding cycles ([~]130+ days) into August. Notably, annual occupancy and breeding success remained stable across years despite strong phenological responses to temperature, suggesting that phenological plasticity may help maintain reproductive performance under current climatic variation. These findings indicate that tropical cavity-nesting frugivores exhibit phenological plasticity coupled with demographic stability, though the mechanisms underlying this apparent buffering remain incompletely understood, and body size-dependent differences in thermal exposure suggest heterogeneous vulnerabilities to future warming scenarios.

ecology↗

bioRxiv2026

Hornbill abundance and habitat correlates in Kali Tiger Reserve, Western Ghats, India-Insights from collaborative monitoring

1.The future of species, particularly large-bodied birds, under climate threats, is increasingly unclear. Protected areas (PAs) can mitigate the impacts of global change, but are not completely immune. This makes it imperative to monitor populations even inside PAs. In the forests of the Western Ghats, three hornbill species are found--Malabar Grey Hornbill, Malabar Pied Hornbill and Great Hornbill. Kali Tiger Reserve, of Karnataka state, India, is known for its healthy hornbill populations, yet few systematic surveys have attempted to estimate their abundance, distributions and habitat affiliations. In this study, we documented the distributions of the three hornbills, estimated the density of Malabar Grey Hornbills and assessed correlates of hornbill encounter rates within the reserve. Malabar Grey Hornbills were the most abundant and widely distributed, found in all ranges of the reserve. Gund, Kadra and Phansoli had the most detections of Malabar Pied and Great Hornbills. Encounter rates of Malabar Grey Hornbill were positively correlated with food-tree stem density, those of Malabar Pied Hornbill negatively correlated with basal area, while those of Great Hornbill not significantly associated with any variable. Malabar Grey Hornbills had a density of 5.1 per km2 (mean flock size = 1.2). While encounter rates of Malabar Pied and Great Hornbills were low, these numbers track the breeding season, when vocal activity is low and females are inside nests. This survey represents a partnership between researchers and the Karnataka forest department, aimed towards inculcating the collaborative spirit of research and monitoring.

ecology↗

bioRxiv2026

Factors shaping frugivory patterns of Asian mammals using a continental-scale dataset

O_LIFrugivores vary in their selection of fruit traits and their fruit handling methods, leading to differences in the plant species they consume for fruits. While fruit consumption patterns of birds are relatively well understood, much less is known about those of mammals. C_LIO_LIGiven the wide morphological and physiological diversity of mammals, fruit consumption patterns and fruit traits selected by different mammal groups may vary substantially. C_LIO_LIWe investigated differences in fruit consumption among three mammal groups - primates, herbivores, and carnivores - in Asia based on peer-reviewed and secondary literature. We assessed both morphological traits and taxonomic composition and compared patterns across vegetation types and for figs and non-figs. We found that primates (29%) and carnivores (21%) consumed more unique fruit genera than herbivores (6%). Carnivores and primates shared more fruit genera with each other (17%) than with herbivores. These patterns were consistent across vegetation types and for figs and non-figs. C_LIO_LIMorphological traits such as fruit size, colour, type, habit, seed number, and seed arillation showed no major differences among mammal groups. C_LIO_LIThere was no significant relationship between mammal body size and the mean or maximum fruit diameter consumed. However, among mammals that handle fruits exclusively with their mouthparts, body size was positively related to the maximum fruit diameter consumed. In contrast, for mammals that handle fruits using opposable thumbs (primates), body size showed a negative relationship with the mean fruit size consumed. There was no significant relationship between mammal activity patterns and the colour of the fruits they consumed. C_LIO_LIOur results suggest that fruit consumption patterns among mammal groups are not strongly differentiated by the morphological traits investigated; however, carnivores and primates are more similar in their preferred fruit genera. Moreover, morphological trait selection may be influenced by fruit handling methods. C_LIO_LIHerbivores consumed larger fruits and, like primates, preferred dull-coloured fruits, whereas carnivores more often fed on liana and shrub fruits across a wider colour range C_LIO_LIFuture research should focus on chemical and quantitative visual traits, such as volatile profiles and nutritional composition, to better understand the drivers of mammal fruit consumption. C_LI

ecology↗

bioRxiv2026

Frugivore species richness influences dietary specialisation and network properties in Asian wet tropical forests

AimTo examine how variation in frugivore species richness influences dietary specialisation and the organisation of plant-frugivore interaction networks in tropical forests. LocationSix undisturbed lowland wet tropical forest sites across four biodiversity hotspots in south and south-east Asia. Time period2016-2024. Major taxa studiedAvian frugivores and fleshy-fruited woody plants. MethodsWe recorded plant-avian frugivore interactions across six undisturbed evergreen forest sites spanning a seven-fold gradient in frugivore species richness, while holding forest type and phylogenetic composition broadly comparable. Using over 4,200 hours of focal observations on 551 fruiting plants, we recorded more than 34,000 feeding visits by 138 frugivore species on 133 plant species. We used a) Joint species distribution models to determine the relative influence of fruit and seed traits, and b) network analyses to evaluate how dietary breadth and network properties varied with frugivore species richness. ResultsAcross sites, frugivore visitation was primarily explained by fruit and seed morphology, with seed size accounting for an average of 39.7% of explained variation, followed by fruit width (24.4%), fruit crop size (21.9%), and pulp lipid content (14.1%). Frugivores in species-rich communities exhibited narrower dietary breadth (Pearsons r = -0.87 between normalised degree and species richness). Correspondingly, plant-frugivore networks became less connected and nested, and more modular, with increasing frugivore richness (Pearsons r = -0.9, -0.98, and 0.84, respectively). Main conclusionsIncreasing frugivore species richness intensifies dietary specialisation, which in turn drives changes in plant-frugivore network structure. These findings highlight how local species richness shapes interaction networks through changes in consumer niche breadth, with implications for the organisation of tropical forest mutualistic communities.

ecology↗

bioRxiv2025

Effects of forest cover, temperature and flower abundance on cashew pollinators in the northern Western Ghats, India

Global declines in pollinators pose serious risks for biodiversity, ecosystem functioning, and human well-being. Understanding how landscape structure and climate shape pollinator communities is critical, yet studies that jointly assess these factors in human-dominated tropical landscapes remain scarce. Here, we investigate how forest cover, distance to forest patches, flower abundance, and temperature influence pollinator communities in monoculture cashew plantations that are rapidly expanding in the northern Western Ghats, part of the Western Ghats-Sri Lanka global biodiversity hotspot. We conducted 210 half-hour observation sessions across 30 cashew orchards in Dodamarg, India. At the community level, flower abundance and forest cover positively influenced pollinator richness, number of pollinators, and number of visits. The number of visits showed a unimodal response to temperature, with peaks occurring within narrow, taxon-specific ranges, lower temperatures for birds and higher for insects, likely reflecting physiological constraints. At the species level, flower abundance and temperature emerged as key predictors of occurrence, while three butterfly species occurred more frequently near forest patches. Contrary to expectations, proximity to forest did not reduce ambient orchard temperatures, suggesting limited forest-mediated thermal buffering in our site. Together, these findings highlight the vulnerability of pollination services to both land-use change and rising temperatures. Ongoing conversion of natural forests to cashew monocultures, coupled with climate warming, may erode pollinator communities and jeopardize crop yields in tropical agroecosystems. More broadly, our results underscore the importance of conserving remnant forests and accounting for thermal sensitivity of pollinators to sustain ecosystem services in changing landscapes worldwide.

ecology↗

bioRxiv2025

Comparing the genetic diversity of two threatened Rhyticeros hornbill species with contrasting geographic range sizes

Island endemics exhibit low genetic diversity due to founder effects and geographical isolation, increasing their vulnerability to inbreeding depression. The Narcondam Hornbill (Rhyticeros narcondami), restricted to the 6.8 km2 Narcondam island in the Andaman archipelago, has the smallest range size among hornbills, a globally threatened group of birds. We compared the genetic diversity of the Narcondam Hornbill with the Wreathed Hornbill (Rhyticeros undulatus) distributed from the Eastern Himalaya to Bali. We generated DNA sequences for four mitochondrial markers ; Cytochrome B (Cytb), cytochrome c oxidase subunit I (COI), NADH dehydrogenase subunit 2 (ND2) and displacement loop (D-loop) regions) from 14 Narcondam Hornbill faecal samples and for three markers (Cytb, COI and ND2) from 19 Wreathed Hornbill tissue samples from north-east India. Our results suggest markedly lower genetic diversity in the island endemic Narcondam Hornbill compared to the Wreathed Hornbill. Specifically, Cytb and COI showed no genetic variation in the island endemic, compared to three to five haplotypes in the Wreathed Hornbills. In the ND2 region, Narcondam Hornbills showed seven haplotypes among 13 samples compared to the Wreathed Hornbills six haplotypes among eight samples. The observed genetic diversity in the D-loop in the Narcondam Hornbill was lower than other island-endemic hornbill species in the Philippines. The extremely low genetic diversity in the Narcondam Hornbill likely stems from a small founder population and/or past hunting pressures that reduced its numbers to approximately 30% of its current population of 1000 birds, rendering the Narcondam Hornbill susceptible to environmental and human-driven changes.

genetics↗

bioRxiv2025

Effects of land-use intensification on nectar resources, bird assemblages and bird-flower interaction networks in the Western Ghats, India

1.Agricultural expansion is a major driver of tropical forest loss globally, making it critical to determine factors that maintain key plant-animal interactions, such as nectarivory, in human-dominated landscapes. In the Paleotropics, which is experiencing rapid expansion of tree crop plantations, few studies have compared floral and nectar-feeding bird communities, their interactions, and network organisation along a tree crop intensification gradient. In a cashew agriculture-forest matrix of the northern Western Ghats of India, we compared forests, cashew agroforests, and cashew monocultures to assess, 1) the abundance, diversity, and composition of flowers and nectar-feeding birds, 2) diversity of bird-flower interactions, and 3) network organisation. Floral abundance declined most sharply in monocultures, followed by agroforests. The abundance and diversity of nectar-feeding birds peaked in agroforests. Forests had the highest floral diversity and bird-flower interactions. Nectivore community composition differed across land-use types, with agroforests harbouring both forest specialists and open-habitat species typically found in monocultures. We found that sunbirds dominated plant-flower interactions across land-use types. After rarefaction (to control for differences in network size), agroforests and monocultures showed higher connectance, specialisation, and modularity than the forest network. Our results suggest that plantations that retain native trees (agroforests) can partially offset the alterations caused in floral resource availability and nectar-feeding bird communities by cashew cultivation. Planting bird-pollinated native tree species along orchard edges can make cashew farming more suitable for nectar-feeding birds, and has the potential to benefit cashew production by attracting avian pollinators.

ecology↗

bioRxiv2025

Listening to children's and educators' experiences in long-term place-based conservation education sessions on southern Indian rocky outcrops

Interactions with nature can influence peoples perceptions of nature and its conservation. Connected to this, there is an increasing research interest in improving childhood nature experiences and environmental awareness through direct outdoor educational activities. While this research largely remains geographically biassed to the nature of temperate regions, global and national policies are pushing towards place-based outdoor environmental education in other geographies where research and theory-practice gap persists. The existing environmental outdoor education literature identifies the on-ground challenges, mostly from educators perspectives and focusing on academic achievements of participants. A better understanding of culturally specific, locally appropriate, and diverse pedagogies, drawing on both childrens and educators voices and relational values is required to fill this gap. We studied [~]20 years old, unique place-based conservation education sessions on the rock outcrops in Kannur (Kerala, India), facilitated by schools and non-governmental organizations. These sessions introduce children to the experience, ecology and conservation issues of rocky outcrops, an easily accessible local socio-ecological system. Considering this as a case-study, using mixed-methods, we aimed to assess (i) if and how these outdoor sessions improve socio-scientific understanding, and positive attitudes towards these habitats and their conservation in children, and to (ii) identify the sessions strengths, challenges, and relational values reflected in them through long-term experiences of its participants and educators. Our within-participant pre- and post-outdoor session surveys showed quantitative evidence for short-term increase in overall knowledge, but not any notable changes in measured attitudes or interests. But, the qualitative analysis of in-depth interviews with children and educators revealed major strengths of the sessions around the Natureculture elements, and relational values; while the challenges were mostly around educators understanding of children, pedagogical design, and logistics. Drawing on the long-term experiences of educators and children in the backdrop of existing global literature on outdoor education, we provide new insights on how using the power of emotions and experiences, positive and solution-oriented outlooks, unique socio-ecological elements, and relational values can be beneficial in designing conservation education sessions in often overlooked geographic and cultural contexts.

scientific communication and education↗

bioRxiv2025

What's next for Indian Ornithology? 101 key research questions

India has a rich history of ornithology, and bird research in this field has expanded considerably in recent decades, spurred by a growing number of birdwatchers and ornithologists. Despite this progress, critical gaps remain. This paper highlights key areas where further research is needed and identifies pressing questions that will shape Indian ornithology in the coming years. Drawing from diverse inputs, we present a curated list of 101 research questions spanning across the various disciplines in ornithology - Natural History, Physiology and Disease Ecology, Behaviour, Population and Community Ecology, Habitat Ecology, Macroecology and Biogeography, Population Genetics and Evolution, Applied/Economic Ornithology and Conservation. The list was compiled through a multi-stage process, starting with a public open call for questions, followed by review and curation by a smaller panel of subject specialists. Each question was independently scored by a panel of experts based on three criteria: generality, novelty, and relevance. To account for variation in scoring styles, scores were normalised using Z-scores. The top 101 research questions were then selected based on these standardised scores. Each question is accompanied by an annotation that describes the significance of the question, and highlights opportunities to address it. While our list of research questions highlights significant research priorities, it is not intended to be exhaustive. Rather, it reflects the perspectives of those involved in its curation, who deemed these questions particularly relevant and impactful towards advancing Indian ornithology. We expect these questions to spark new project ideas among students, researchers, and citizen scientists, while guiding funders, managers, and policymakers toward priority research areas.

ecology↗

bioRxiv2025

De novo genome assemblies of threatened Asian hornbills (Bucerotidae) reveal declining population trajectories during the late Pleistocene

2.Asian hornbills are flagship species of the wet tropics that face significant threats from hunting, habitat loss, and fragmentation. Despite being conservation flagships, whole genome information is available for only two of the 32 Asian hornbill species. In this study, we provide the first de novo genome assemblies for four hornbill species (Bucerotidae) in Asia. We present hybrid genome assemblies for Buceros bicornis and Rhyticeros undulatus, and short-read genomes for Anthracoceros coronatus, and Aceros nipalensis. The genome sizes of these hornbills range from 1.1 Gb to 1.3 Gb with over 93% completeness and gene prediction BUSCO. We also provide annotated mitogenomes for each of these species. Furthermore, we estimated Pleistocene population trajectories for these four species, which vary in their habitat preferences. Our results indicate that Pleistocene climatic fluctuations have led to dramatic population declines in all four species. We believe that this study provides robust genomic resources to support future conservation genomics efforts for hornbills.

genomics↗

bioRxiv2025

Understudied and underprotected: biodiversity and conservation challenges in the Konkan region of Maharashtra

In biodiversity hotspots, such as the Western Ghats, periodic synthesis of existing ecological research can help identify knowledge gaps and address critical threats to biodiversity. The Maharashtra part of the Konkan region, situated between the Sahyadri foothills and the west coast, with diverse tropical vegetation, harbours unique open ecosystems, such as lateritic plateaus, and supports a multitude of threatened species, including hornbills and tigers. However, the region remains relatively understudied and has not received adequate protection through state or national conservation policies and laws. The area is undergoing rapid human-driven land-use change. These activities can impact the regions biodiversity, necessitating an effort to identify knowledge gaps and critical threats. Through a combination of a literature review and focus group discussions with 44 participants from various institutions and non-governmental organisations, we synthesised existing published information on the Konkan region of Maharashtra and identified key research gaps and conservation challenges. Our review of 138 studies found that while agroforestry and human-wildlife interactions have received some research attention, the effects of climate change on the regions biodiversity remain poorly understood. Focus group discussions highlighted major threats, including land-use changes due to expanding monoculture plantations, clear-felling of forests, forest fires, environmental pollution, and rapid infrastructure development, which are leading to habitat loss and fragmentation. Some of these concerns were validated by publicly available regional data, which revealed a 30% increase in roads, a 14% expansion of cashew plantations, and associated forest loss. This synthesis offers valuable insights for government and non-governmental organisations to inform future research and conservation efforts in the region.

ecology↗

bioRxiv2025

Effects of tree plantations on population and roosting ecology of an endemic agamid lizard in Western Ghats Biodiversity Hotspot

Low-elevation wet tropical forests support herpetofaunal diversity but are increasingly replaced by monoculture tree plantations and have poor Protected Area coverage, leaving herpetofauna vulnerable. Research on how monoculture plantations affect reptile populations remains inconclusive, and the ecology of endemic species in these changing landscapes is poorly understood. We compared densities and roosting ecology of Monilesaurus rouxii, an endemic agamid lizard, across low- and high-elevation forests and cashew and rubber plantations in the Western Ghats Biodiversity Hotspot using nocturnal transects. We found that low-elevation forests, despite poor Protected Area coverage, had significantly higher densities of Monilesaurus rouxii than high-elevation forests and cashew plantations. Roost site use did not differ significantly across the different land-use, indicating roost fidelity. However, Monilesaurus rouxii exhibited ontogenetic shifts in roosting substrate and height. Our findings highlight the conservation importance of unprotected low-elevation forests, which are rapidly being converted to monoculture tree plantations. We show that plantation types may differ in their impacts on reptile populations. We also show the utility of nocturnal transects for population estimation of diurnal lizards.

ecology↗

bioRxiv2025

Effects of frugivore species pool and seed size on the diversity and functional composition of frugivores visiting fruiting trees

The relationship between biodiversity and ecosystem functioning in seed dispersal remains understudied despite its critical role in maintaining plant diversity in the tropics. Field studies on this relationship are often confounded by environmental and phylogenetic variations across species richness gradients. We examined how overall avian frugivore species richness at a site influenced the frugivore richness, visitation rates and functional composition of two key effect traitsbeak width and hand-wing indexon fruiting trees. Across six sites in tropical Asia, spanning a sevenfold gradient in frugivore species richness but with similar forest types and phylogenetically nested frugivore communities, we recorded 34,014 interactions between 134 avian frugivores and 131 plant species. Our results provide some support for the biodiversity-ecosystem functioning relationship, as higher overall frugivore species richness increased the number of frugivore species visiting individual fruiting trees but not the functional composition of frugivores. Seed size had a stronger influence on the frugivore species richness, visitation rates, and the beak size of visiting frugivores, highlighting the dominant role of morphological trait matching in influencing plant-frugivore interactions. Our findings suggest functional redundancy in certain aspects of seed dispersal effectiveness due to density compensation and the presence of key seed disperser lineages in species-poor sites.

ecology↗

bioRxiv2024

Age and sex influence seed dispersal of native and non-native plants by Lion-tailed Macaques Macaca silenus

While interspecific variation in seed dispersal, a critical ecosystem process in tropical forests, is relatively well-studied, intraspecific variation as a consequence of differences in body size, foraging behaviours, and ranging patterns among age-sex categories within a species is relatively understudied. Among vertebrates, primates play a critical role in seed dispersal and exhibit behavioural differences between age and sex categories, making them a suitable study system for intraspecific variation in seed dispersal. Lion-tailed macaques Macaca silenus, an endemic and predominantly frugivorous primate species in the Western Ghats Biodiversity Hotspot, provide an excellent model for such studies. We examined the influence of age and sex on 1) the diversity and 2) the quantity of native and non-native fruits consumed, 3) the number of seeds dispersed, 4) seed dispersal distance, and 5) seed deposition substrates in lion-tailed macaques. We conducted over 375 hours of focal animal watches, distributed evenly across adult males, females, and subadults. Our findings showed that subadults consumed a higher diversity of native and non-native fruits than females and males. They dispersed fewer Ficus seeds than females. We found differences in the proportions of non-native fruits in the diets of different age- sex categories. Males consumed more Coffea liberica, whereas females and subadults fed on Coffea and Lantana. We found weak evidence suggesting that males were more likely to disperse Ficus seeds on trees, which are suitable substrates for Ficus establishment. Our study highlights that age and sex significantly influence seed dispersal patterns of native and non- native species by an endemic, frugivorous primate species with potential influence on recruitment.

ecology↗

bioRxiv2024

Native trees within plantations and surrounding forest cover are essential for bird conservation in cashew-dominated landscapes within a biodiversity hotspot

O_LIAnnually, agriculture is responsible for about 60% of tropical forest loss globally. C_LIO_LIstrategies in agricultural landscapes range from enhancing farm-level habitat diversity to retaining forest cover within landscapes. A critical question is determining the relative influence of native trees within farms and forest cover around them on avian diversity, trait responses and species persistence in tree-based systems in landscapes where protected areas are often absent, often the case in lowland tropical forest ecosystems. C_LIO_LIBy sampling birds across gradients of cashew plantation intensification and varying levels of surrounding cashew and forest cover, we examined the relative influence of site- and landscape-level factors on species composition, taxonomic, functional, and phylogenetic diversity, as well as species- and trait-specific responses, and whether phylogenetic relationships among bird species influenced these responses. C_LIO_LIAt the community level, forests, cashew agroforests, and cashew monocultures hosted compositionally different bird communities. Site-level variables, specifically the proportion of native trees, influenced taxonomic and phylogenetic diversity, while landscape-level variables had no effect. None of the predictor variables accounted for the variation in functional diversity. C_LIO_LIAt the species level, site-level variables, specifically the proportion of native trees, and landscape-level variables, particularly cashew cover around plantations, had positive and negative impacts on species responses, respectively. At the trait level, evergreen forest specialists were associated positively with the proportion of native trees and negatively associated with cashew cover. Resident species had a positive association with forest cover. We found a phylogenetic signal in species responses to predictor variables, indicating that closely-related species responded similarly to predictor variables. C_LIO_LISynthesis and applications: To retain taxonomic and phylogenetic diversity and ensure persistence of evergreen forest specialists, it is essential to retain native trees within cashew plantations and maintain surrounding forest cover. Future policies should incentivise the retention and restoration of forest patches and restrict the felling of native trees within cashew plantations. C_LI

ecology↗

bioRxiv2024

Patterns of leaf, flower and fruit phenology and environmental relationships in a seasonal tropical forest in the Indian Eastern Himalaya

Tree phenology plays an important role in determining the structure and function of tropical forest communities. However, there are few long-term studies on tree phenology from South Asia. We monitored 716 trees of 54 species monthly from 2011 to 2023 for leaf flush, flowering, and fruiting in Pakke Tiger Reserve, Arunachal Pradesh, India. We examined monthly patterns in the percentage of species and trees in leaf flush, flower and fruit and characterized phenological seasonality using circular statistics. Flowering periodicity was classified using Fourier analysis and we examined the relationships between phenological activity and temperature, rainfall, solar radiation and daylength using GAMLSS. Leaf flush and flowering were moderately seasonal, peaking in the warm dry season months of March to May. Fruiting patterns and their seasonality differed among dispersal modes. At the community level and for bird-dispersed species, fruiting was bimodal and relatively aseasonal, peaking in April and October. The highly seasonal fruiting of mammal-dispersed species peaked in October, while that of mechanically-dispersed species was bimodal and concentrated in the dry season months. The majority of species (78.13%) and trees (51.17%) flowered annually. Daylength, solar radiation and minimum temperature had significant nonlinear effects on phenology. This indicated the existence of narrow ranges of optimal climatic conditions for phenology, which could be affected by climate change. Our study emphasizes the need for long-term monitoring to rigorously quantify phenological patterns, particularly in the context of rapid global change.

plant biology↗

bioRxiv2024

Effects of land use change and elevation on endemic shrub frogs in a biodiversity hotspot

Agroforestry, often promoted as a sustainable agriculture practice, is rapidly expanding, often at the cost of primary tropical forests. While agroforestry impacts amphibian diversity negatively, its effects on population demography, microhabitat use and body condition are relatively understudied. This information is crucial for determining and promoting amphibian-friendly land use practices. We compared habitats, population densities, microhabitat use, and body condition of two endemic species of shrub frogs (Pseudophilautus amboli and Raorchestes bombayensis) across 1) elevations (low- and high-elevation forests) and 2) land use categories (cashew, rubber, and low-elevation forests) in the northern part of the Western Ghats Biodiversity Hotspot. Using distance sampling, we demonstrated that abundances of the two shrub frog species differed across elevation categories, with Pseudophilautus more common in low-elevation forests and Raorchestes more prevalent in high-elevation forests. Both species of frogs exhibited extremely skewed, male-biased sex ratios, with three females for 100 males. Pseudophilautus had lower densities and poor recruitment and exhibited altered microhabitat use in cashew plantations compared to low-elevation forests. Although adult male Pseudophilautus densities in rubber were similar to those in low-elevation forests, they exhibited altered microhabitat use and smaller body sizes than in forests, indicating poor body condition. We demonstrate differential impacts of agroforestry types on shrub frogs. We also demonstrate that distance sampling can be a useful tool for population monitoring of shrub frogs, which comprise almost 25% of the anuran diversity in the Western Ghats. Additionally, there is a need to identify the drivers of extremely skewed sex ratios, which make these species vulnerable to population crashes. Considering the recent downlisting of the two focal species to Least Concern, we advocate for their uplisting to at least Near Threatened status in light of their patchy distribution, negative impacts of rapidly expanding agroforestry plantations and extremely skewed sex ratios.

ecology↗