A mechanistic model of snakebite as a zoonosis: Envenoming incidence is driven by snake ecology, socioeconomics and its impacts on snakes.

Snakebite is the only WHO-listed, not infectious neglected tropical disease (NTD), although its eco-epidemiology is similar to that of zoonotic infections: envenoming occurs after a vertebrate host contacts a human. Accordingly, snakebite risk represents the interaction between snake and human factors, but their quantification has been limited by data availability. Models of infectious disease transmission are instrumental for the mitigation of NTDs and zoonoses. Here, we represented snake-human interactions with disease transmission models to approximate geospatial estimates of snakebite incidence in Sri Lanka, a global hotspot. Snakebites and envenomings are described by the product of snake and human abundance, mirroring directly transmitted zoonoses. We found that human-snake contact rates vary according to land cover (surrogate of occupation and socioeconomic status), the impacts of humans and climate on snake abundance, and by snake species. Our findings show that modelling snakebite as zoonosis provides a mechanistic eco-epidemiological basis to understand snakebites, and the possible implications of global environmental and demographic change for the burden of snakebite

Integrating human behavior and snake ecology with agent-based models to predict snakebite in high risk landscapes.

Snakebite causes more than 1.8 million envenoming cases annually and is a major cause of death in the tropics especially for poor farmers. While both social and ecological factors influence the chance encounter between snakes and people, the spatio-temporal processes underlying snakebites remain poorly explored. Previous research has focused on statistical correlates between snakebites and ecological, sociological, or environmental factors, but the human and snake behavioral patterns that drive the spatio-temporal process have not yet been integrated into a single model. Here we use a bottom-up simulation approach using agent-based modelling (ABM) parameterized with datasets from Sri Lanka, a snakebite hotspot, to characterise the mechanisms of snakebite and identify risk factors. Spatio-temporal dynamics of snakebite risks are examined through the model incorporating six snake species and three farmer types (rice, tea, and rubber). We find that snakebites are mainly climatically driven, but the risks also depend on farmer types due to working schedules as well as species present in landscapes. Snake species are differentiated by both distribution and by habitat preference, and farmers are differentiated by working patterns that are climatically driven, and the combination of these factors leads to unique encounter rates for different landcover types as well as locations. Validation using epidemiological studies demonstrated that our model can explain observed patterns, including temporal patterns of snakebite incidence, and relative contribution of bites by each snake species. Our predictions can be used to generate hypotheses and inform future studies and decision makers. Additionally, our model is transferable to other locations with high snakebite burden as well

Climate change maladaptation for health: Agricultural practice against shifting seasonal rainfall affects snakebite risk for farmers in the tropics.

Snakebite affects more than 1.8 million people annually. Factors explaining snakebite variability include farmers' behaviors, snake ecology and climate. One unstudied issue is how farmers' adaptation to novel climates affect their health. Here we examined potential impacts of adaptation on snakebite using individual-based simulations, focusing on strategies meant to counteract major crop yield decline because of changing rainfall in Sri Lanka. For rubber cropping, adaptation led to a 33% increase in snakebite incidence per farmer work hour because of work during risky months, but a 17% decrease in total annual snakebites because of decreased labor in plantations overall. Rice farming adaptation decreased snakebites by 16%, because of shifting labor towards safer months, whereas tea adaptation led to a general increase. These results indicate that adaptation could have both a positive and negative effect, potentially intensified by ENSO. Our research highlights the need for assessing adaptation strategies for potential health maladaptations

Mapping and assessment of vegetation types in the tropical rainforests of the Western Ghats using multispectral Sentinel-2 and SAR Sentinel-1 satellite imagery

Detailed mapping and regular monitoring of tropical rainforests is important for conservation and management of highly fragmented tropical rainforest habitats and biodiversity. Several studies have observed that it is highly challenging to map different vegetation types in tropical rainforests due to large environmental heterogeneity, high topographical variability and near constant cloud cover. In the present study, we assessed the capability of optical multispectral Sentinel-2 MSI bands, their derived NDVI and textures, and SAR Sentinel-1 bands and their textures to discriminate different vegetation types in the tropical rainforests of the Western Ghats using maximum likelihood and random forest classification. We also compared the results of our classification with previous such maps of the study area. Finally, we evaluated the magnitude of habitat fragmentation by using derived landscape metrics. Our classification had high accuracy (>75), especially compared to previous classification efforts. Our results emphasise the significance of using vegetation indices and textures for vegetation type classification in the Western Ghats. Furthermore, the results suggest that rainforest habitats and other agro-ecosystems, suitable as habitats for numerous plant and animal species, are highly fragmented and require top conservation priority. High spectral and spatial resolution, continuity, affordability and access makes Sentinel-2 one of the best options for regular monitoring of tropical rainforests

Behavioural variability in macaques and langurs of the western ghats, India

Studies that compare differences in the behavioural variability across species and genera are rare among south Asian primates. Such studies are important for understanding within-group feeding competition in primates as interindividual difference in frequency of behaviour is a good indicator of feeding competition. We compared the variability in individual activities of lion-tailed macaques, bonnet macaques, Nilgiri langurs, and black-footed grey langurs. Both macaque species showed variability in their activities, with bonnet macaques showing higher variability than lion-tailed macaques. This indicated higher within-group competition in bonnet macaques than in lion-tailed macaques. Folivorous Nilgiri langurs and black-footed grey langurs did not show variability in any behaviour, indicating weak or negligible within-group competition. Except in the bonnet macaque, the interindividual differences in activities in the other species were potentially due to the differences between lactating and non-lactating females. We observed that langurs were less variable than macaques, indicating higher within-group competition in macaques than in langurs. We also observed a higher frequency of aggressive interactions during feeding among macaques than langurs, substantiating higher within-group competition in macaques than in langurs. We further discuss the different possibilities of within-group contest and scramble competition in these species

Social‐ecological cascade effects of land use on vertebrate pest dynamics in arid agricultural communities

Extensive land conversion to agriculture in drylands and associated resource use have wide‐ranging impacts on desert ecosystems globally. Incorporating the impacts of human‐social aspects is thus imperative in examining ecological interactions. The provision of agricultural inputs in these resource‐scarce regions supports invasive and pest species, negatively impacting both agricultural productivity and native desert ecosystems. Understanding the spatial dynamics of invasive and pest species requires analyzing both bottom‐up resource availability factors underlying animal distributions and top‐down biological controls. Here, we evaluate the social‐ecological cascading effects of dryland agriculture on vertebrate pest communities in dryland agricultural communities of Israel. Our study region is characterized by 18 agricultural cooperatives with distinct crop regimes due to contrasting social decision‐making and resource allocation schemes (i.e., communal kibbutzim vs. privatized moshavim). Crop choices further affect land management (e.g., enclosed vs. open farm systems) and resource intensity. This system is ideal for studying trophic mechanisms underlying animal assemblages between agricultural regimes. We examine the role of agricultural land‐use practices on pest spatial distributions based on multiyear vertebrate pest observations with agricultural data sets. We use structural equation modeling (SEM) to quantify the relative importance of added agricultural resources underlying bottom‐up and top‐down trophic processes regulating vertebrate pest assemblages. Results reveal that crop choices determine pest distributions through bottom‐up processes directly, while simultaneously driving pest competitive interactions through indirect top‐down cascades impacting pest communities. For example, due to the indirect negative effect of wolves on mesopredators (foxes and jackals) mediated by livestock, the total positive effect of livestock on the abundance of mesopredators is reduced. Our study illustrates the social‐ecological cascading effects of agricultural regimes on pest community assemblages mediated by contrasting agricultural land‐use practices. Considering the expansion of dryland agroecological systems globally, understanding the intricate cascading pathways of predator‐ and prey‐pest communities has important implications for agricultural management, biological invasions in drylands, and fragile desert environments

Interactions of lion-tailed macaque (Macaca silenus) with non-primates in the Western Ghats, India

Primates and non-primates inhabiting tropical forests may interact with each other since they coexist in the same communities. Primates usually interact with their prey, predators, competitors and neutral species. Using ‘all occurrence’ sampling, we have studied inter-specific interactions of lion-tailed macaques with non-primate species found in their habitat. We ob-served that the percentage of total time spent on in-teractions with non-primates was less than 1. Also, the percentage of total time spent in interacting with competitors, predators and neutral species was less than 0.5. The lack of predation pressure and lack of opportunities for mixed-species associations for in-creasing foraging efficiency appear to be the major reasons for the absence of interactions with non-primates. By comparing with studies from other pri-mate habitat regions, we observed that primates in South Asia interact much lesser with non-primates than those in South America and Africa. A previous study showed that the interactions of lion-tailed ma-caques even with other primate species in the Western Ghats are less than expected by chance

Drastic population decline and conservation prospects of roadside dark-bellied bonnet macaques (Macaca radiata radiata) of Southern India

We carried out a survey on roadside dark-bellied bonnet macaques (Macaca radiata radiata) on the highways around the south Indian city of Mysore. The present survey was the fourth since 1989 on the same populations. We divided the habitats into intensive cultivation (IC), wet cultivation (WC), and scrub forests (SC). The number of groups has significantly reduced from 54 to 31 and the number of animals has declined from 1,207 to 697 from 1989 to 2009. This decline has been recorded only in the IC and WC areas, whereas the population in SC with places of Hindu worship has remained stable. Due to the loss of roadside Ficus trees over the years, the habitat of the monkeys has almost disappeared. Since bonnet macaque is not primarily a forest-dwelling species, the seemingly widespread primate may soon become 'threatened' if the non-forest populations continue to decline. Scrub forests in small hillocks housing Hindu temples remain the only prospective places for conservation of bonnet macaques

Male Chemical Signalling to Recruit Females in the Greater Short-Nosed Fruit Bat Cynopterus sphinx

Rathinakumar A, Baheerathan M, Caspers B, et al. Male Chemical Signalling to Recruit Females in the Greater Short-Nosed Fruit Bat Cynopterus sphinx. Acta Chiropterologica. 2021;23(1)