1,720,960 research outputs found
Interactions of large felids with their prey and humans in the Yucatán Peninsula of Mexico and Belize
No full textTropical-forest biodiversity is currently undergoing an unprecedented mass extinction caused by human exploitation of natural resources, and fragmentation and loss of forest habitat in conversion to human uses. Felids (wild cats) are particularly vulnerable because of their requirements for contiguous tracts of forest. This thesis addresses the status and value to human wellbeing of natural capital associated with felids that have biotic boundaries extending beyond the boundaries of areas designated for their protection. The principal aim is to evaluate locally viable conservation options for minimising human-wildlife conflict, in relation to populations of jaguars and pumas and their prey that occupy discontinuous areas of protected forest interspersed with farmland. Chapter 1 introduces the general context and background to this issue. Chapter 2 uses empirical data from systematic surveys by camera-trapping and scat sampling to estimate the availability of prey to jaguars and pumas in and between two small private nature reserves in the Northern Yucatán Peninsula. The chapter delivers the first sex-specific estimate of jaguar abundance in the area. It evaluates presence and abundance of potential prey for jaguars and pumas, and associations between daily activity patterns of jaguars and pumas with their prey. It quantifies jaguar and puma diets, and assesses prey exploitation and niche overlap. Chapter 3 uses questionnaire surveys to evaluate human-wildlife interactions between Maya communities and large felids. It includes a first assessment of perceptions about wildlife, hunting and wild meat consumption in the Northern Yucatán Peninsula. The chapter delivers an evaluation of livestock management practices, wild-meat consumption, hunting habits and experiences of human-wildlife conflict. Chapter 4 addresses the need to monitor cryptic sources of human exploitation of natural forest resources in the Yucatán Peninsula. The chapter describes the development and testing of a probabilistic method for near-optimal placement of acoustic loggers to detect and localise gunshots. Field tests in Mexico and Belize demonstrate for the first time the potential for flooding large areas of forest with small and low-cost acoustic devices to monitor rates of hunting activity. Chapter 5 delivers a synthesis of general conclusions from the study. Within the Northern Yucatán Peninsula, jaguars and pumas were found to have largely overlapping resource niches and activity patterns, consistent with a lack of options for niche separation in this heavily human modified and disturbed habitat. There was little evidence of declines in their populations with respect to earlier studies, despite ongoing habitat fragmentation. The viability of these large felids depends entirely on their ability to sustain access to prey in unprotected forests between nature reserves, as well as effective protection of prey in the reserves. Maya communities report a generally reducing availability of game – which are also prey to large felids – in the unprotected forests. They also report attacks by large felids on their livestock which, although infrequent, have potential to inflict severe economic injury. Hunters attributed a lack of game to overhunting in unprotected forests, and expressed a desire for support on this issue. The recent development of low-cost and power-efficient acoustic loggers opens up new potential for rural communities to monitor rates of hunting and logging, as a first step to policing their own natural resources
Densidad poblacional y caracterización de hábitat del venado cola blanca en un bosque templado de Oaxaca, México.
Full text linkSe evaluó la densidad poblacional y se caracterizó el hábitat del venado cola blanca Odocoileus virginianus en un bosque templado de Santa María Yavesía, Sierra Norte de Oaxaca. Se realizaron dos muestreos temporales en 13 sitios pertenecientes a cinco asociaciones vegetales con el método de conteos de grupos fecales. Se calculó la densidad poblacional con el modelo de Eberhardt & Van Etten (1956) usando dos tasas de defecación. Se registró la presencia de venados sólo en el bosque de coníferas y el bosque de pino-encino cerrado. Las densidades promedio encontradas entre marzo a julio de 2008 fueron de 1.30 ± 3.04 individuos/km2 y de 0.49 ± 1.14 individuos/km2. Se midieron 13 variables del hábitat del venado cola blanca (vegetación y atributos físicos). Los sitios en el bosque de coníferas están a mayor altitud, son más fríos y húmedos, tienen más árboles grandes y un estrato arbustivo abierto. Las densidades poblacionales encontradas en el presente estudio fueron bajas, comparadas con las encontradas en otros estudios realizados con el método de conteo de grupos fecales en el país. Se proponen recomendaciones de manejo para los venados cola blanca de Santa María Yavesía.Se evaluó la densidad poblacional y se caracterizó el hábitat del venado cola blanca Odocoileus virginianus en un bosque templado de Santa María Yavesía, Sierra Norte de Oaxaca. Se realizaron dos muestreos temporales en 13 sitios pertenecientes a cinco asociaciones vegetales con el método de conteos de grupos fecales. Se calculó la densidad poblacional con el modelo de Eberhardt & Van Etten (1956) usando dos tasas de defecación. Se registró la presencia de venados sólo en el bosque de coníferas y el bosque de pino-encino cerrado. Las densidades promedio encontradas entre marzo a julio de 2008 fueron de 1.30 ± 3.04 individuos/km2 y de 0.49 ± 1.14 individuos/km2. Se midieron 13 variables del hábitat del venado cola blanca (vegetación y atributos físicos). Los sitios en el bosque de coníferas están a mayor altitud, son más fríos y húmedos, tienen más árboles grandes y un estrato arbustivo abierto. Las densidades poblacionales encontradas en el presente estudio fueron bajas, comparadas con las encontradas en otros estudios realizados con el método de conteo de grupos fecales en el país. Se proponen recomendaciones de manejo para los venados cola blanca de Santa María Yavesía
Knowledge of wildlife, hunting, and human-felid interactions in Maya Forest communities of the Northern Yucatan Peninsula, Mexico
No full textHuman-wildlife impacts threaten large-felid persistence in the northern Yucatán Peninsula, triggered largely by livestock depredation. We aimed to explore knowledge and attitudes about local wildlife in relation to husbandry practices, hunting habits, and human-wildlife interactions, in three Maya Forest communities. A questionnaire survey of 30 long-established smallholdings, where livelihood depended on a private fenced plot and surrounding communal forest, found wide knowledge of local wildlife, perception biases for abundances of game species, and preference for living amongst wild herbivores over carnivores. Interviewees had concerns about perceived year-on-year decreases in local wildlife, attributed to regular subsistence hunting by their communities. The few interviewees reporting large-felid attacks on their livestock subsequently altered management practices to prevent further attacks. The region suffers from a poverty trap of subsistence hunting by smallholders needing protein supplement potentially exacerbating depredation on the livestock that sustain their economies by large felids deprived of their natural pre
Optimization of sensor deployment for acoustic detection and localization in terrestrial environments
Full text linkThe rapid evolution in miniaturization, power efficiency and affordability of acoustic sensors, combined with new innovations in smart capability, are vastly expanding opportunities in ground-level monitoring for wildlife conservation at a regional scale using massive sensor grids. Optimal placement of environmental sensors and probabilistic localization of sources have previously been considered only in theory, and not tested for terrestrial acoustic sensors. Conservation applications conventionally model detection as a function of distance. We developed probabilistic algorithms for near-optimal placement of sensors, and for localization of the sound source as a function of spatial variation in sound pressure. We employed a principled-GIS tool for mapping soundscapes to test the methods on a tropical-forest case study using gunshot sensors. On hilly terrain, near-optimal placement halved the required number of sensors compared to a square grid. A test deployment of acoustic devices matched the predicted success in detecting gunshots, and traced them to their local area. The methods are applicable to a broad range of target sounds. They require only an empirical estimate of sound-detection probability in response to noise level, and a soundscape simulated from a topographic habitat map. These methods allow conservation biologists to plan cost-effective deployments for measuring target sounds, and to evaluate the impacts of sub-optimal sensor placements imposed by access or cost constraints, or multipurpose uses.</p
AudioMoth: Evaluation of a smart open acoustic device for monitoring biodiversity and the environment
Full text link1. The cost, usability and power efficiency of available wildlife monitoring equipment currently inhibits full ground-level coverage of many natural systems. Developments over the last decade in technology, open science, and the sharing economy promise to bring global access to more versatile and more affordable monitoring tools, to improve coverage for conservation researchers and managers.2. Here we describe the development and proof-of-concept of a low-cost, small-sized and low-energy acoustic detector: 'AudioMoth'. The device is open-source and programmable, with diverse applications for recording animal calls or human activity at sample rates of up to 384kHz. We briefly outline two ongoing real-world case studies of large-scale, long-term monitoring for biodiversity and exploitation of natural resources. These studies demonstrate the potential for AudioMoth to enable a substantial shift away from passive continuous recording by individual devices, towards smart detection by networks of devices flooding large and inaccessible ecosystems.3. The case studies demonstrate one of the smart capabilities of AudioMoth, to trigger event logging on the basis of classification algorithms that identify specific acoustic events. An algorithm to trigger recordings of the New Forest cicada (Cicadetta montana) demonstrates the potential for AudioMoth to vastly improve the spatial and temporal coverage of surveys for the presence of cryptic animals. An algorithm for logging gunshotevents has potential to identify a shotgun blast in tropical rainforest at distances of up to 500 m, extending to 1km with continuous recording.4. AudioMoth is more energy efficient than currently available passive acoustic monitoring (PAM) devices, giving it considerably greater portability and longevity in the field with smaller batteries. At a build cost of ~US$43 per unit, AudioMoth has potential for varied applications in large-scale, long-term acoustic surveys. With continuing developments in smart, energy-efficient algorithms and diminishing component costs, we are approaching the milestone of local communities being able to afford to remotely monitor their own natural resources
Automated detection of gunshots in tropical forests using convolutional neural networks
Full text linkUnsustainable hunting is one of the leading drivers of global biodiversity loss, yet very few direct measures exist due to the difficulty in monitoring this cryptic activity. Where guns are commonly used for hunting, such as in the tropical forests of the Americas and Africa, acoustic detection can potentially provide a solution to this monitoring challenge. The emergence of low cost autonomous recording units (ARUs) brings into reach the ability to monitor hunting pressure over wide spatial and temporal scales. However, ARUs produce immense amounts of data, and long term and large-scale monitoring is not possible without efficient automated sound classification techniques. We tested the effectiveness of a sequential two-stage detection pipeline for detecting gunshots from acoustic data collected in the tropical forests of Belize. The pipeline involved an on-board detection algorithm which was developed and tested in a prior study, followed by a spectrogram based convolutional neural network (CNN), which was developed in this manuscript. As gunshots are rare events, we focussed on developing a classification pipeline that maximises recall at the cost of increased false positives, with the aim of using the classifier to assist human annotation of files. We trained the CNN on annotated data collected across two study sites in Belize, comprising 597 gunshots and 28,195 background sounds. Predictions from the annotated validation dataset comprising 150 gunshots and 7044 background sounds collected from the same sites yielded a recall of 0.95 and precision of 0.85. The combined recall of the two-step pipeline was estimated at 0.80. We subsequently applied the CNN to an un-annotated dataset of over 160,000 files collected in a spatially distinct study site to test for generalisability and precision under a more realistic monitoring scenario. Our model was able to generalise to this dataset, and classified gunshots with 0.57 precision and estimated 80% recall, producing a substantially more manageable dataset for human verification. Using a classifier-guided listening approach such as ours can make wide scale monitoring of threats such as hunting a feasible option for conservation management
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Bridging conservation and policy: evaluating national capacity to reduce mangrove loss under the Kunming-Montreal Biodiveristy Framework
No full textThe Kunming-Montreal Global Biodiversity Framework (GBF) aims to halt biodiversity loss by 2030, with Targets 1 and 3 focusing on reducing forest loss and expanding protected areas. Mangroves, as biodiversity hotspots offering crucial ecosystem services, have seen some conservation gains, yet key drivers of high-value mangrove loss remain unaddressed in intergovernmental policy frameworks. It is the first global assessment linking GBF Targets 1 & 3 to mangrove loss drivers and ecosystem assessment. We apply an interdisciplinary approach—combining global-scale geospatial analysis of mangrove loss trajectories between 2000 and 2016 and ecosystem value distribution, and thematic policy analysis. We classify all 120 countries where mangroves are present by their short- and long-term mangrove loss management strategies and evaluate the inclusion of relevant actions under Targets 1 and 3 of National Biodiversity Strategies and Action Plans (NBSAPs). Between 2000 and 2016, 78% of mangrove loss occurred in areas rich in biodiversity, biomass, and coastal protection, mostly outside protected zones. Of 120 mangrove-holding countries, 30 (25%) experienced significant loss. Among them, 11 have the potential to implement short-term mitigation by expanding or managing protected areas, though only 5 included these strategies in national targets. Four countries referenced broader measures like indigenous rights and the prioritisation of ecosystem service hotspots. Only Cameroon, Colombia, Gabon, Panama, and Tanzania are positioned to address major loss drivers within the GBF timeline. This paper is the first global assessment of GBF-aligned national targets to mitigate mangrove loss, contributing to SDGs 14 and 15. We show that mangrove loss cannot be halted by 2030 under the current level of national targets. Policy amendments at national scales can include short-term (area-based protection) and long-term strategies (restoration, rehabilitation and ecosystem-based approaches) to halt mangrove loss
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