Andrew Whitworth

• PhD
• Director at Osa Conservation

Traditionally, arboreal rainforest mammals have been inventoried using ground-based survey techniques. However, given the success of camera traps in detecting secretive terrestrial rainforest mammals, camera trapping could also be a valuable tool for inventorying arboreal species. Here we assess, for the first time, the effectiveness of arboreal ca...

Aim: Community-level assessments of how biodiversity responds to disturbance within forest habitats are often biased towards terrestrial-based surveys. However, recent research suggests that arboreal communities of several indicator groups (ants, amphibians, beetles and butterflies) are more susceptible to human disturbance than their terrestrial...

Background and Research aims The extinction of relict and rare tree species is accelerated by habitat loss and climate change. Pleodendron costaricense is a critically endangered tree, with only four mature individuals known in Southern Pacific Costa Rica. With the discovery of three additional trees, we set out to learn more about P. costaricense’...

For decades sea turtle projects around the world have monitored nesting females using labor-intensive human patrolling techniques. Here we describe the first empirical testing of a drone-mounted thermal infrared sensor for nocturnal sea turtle monitoring; on the Osa peninsula in Costa Rica. Preliminary flights verified that the drone could detect s...

Given the rate of biodiversity loss, there is an urgent need to understand community-level responses to extirpation events, with two prevailing hypotheses. On one hand, the loss of an apex predator leads to an increase in primary prey species, triggering a trophic cascade of other changes within the community, while density compensation and ecologi...

Neotropical porcupines (Coendou spp.) remain poorly studied, with much of our knowledge derived from anecdotal observations or research on captive individuals. In this study, we used camera traps across multiple survey designs-an arboreal grid, a terrestrial grid, and at mineral licks-to investigate habitat use and geophagy in sympatric porcupine s...

Carcass consumption by scavengers plays a critical role in wildlife and human health by providing services that maintain ecosystem functioning and potentially mitigate disease spreading. Vultures are particularly efficient scavengers, but their populations have sharply declined in Europe, Asia and Africa, raising concerns about similar declines in...

Tropical forests harbor much of Earth’s biodiversity, with the ground to emergent canopy forming dynamic three-dimensional habitats. Arboreal and semi-arboreal species navigate the vertically heterogeneous environment, in temperature, light, predation risk, and resource availability, responding to further diel, lunar, and seasonal changes. While di...

Camera traps are widely used to study wildlife. However, theft and vandalism are frequent, resulting in millions of dollars in financial losses and large data gaps in research. Here we report on the impacts of camera-trap theft on a study examining wildlife movement under highway bridges in south-west Costa Rica. Even with metal cases, locks and si...

This study provides new insights into the behavioral ecology of Dinomys branickii based on long-term camera trap surveys conducted at three sites along an altitudinal gradient in southeastern Peru. Notably, we document the first known cases of geophagy in this species, which suggests a highly herbivorous diet. Moreover, in contrast to previous repo...

Background As obligate scavengers, New World vultures (Cathartiformes: Cathartidae) play a key role in carcass removal and disease control. Associated with this ecosystem service, vultures are exposed to the consumption of harmful substances such as poisons, heavy metals, antibiotics, or non‐steroidal anti‐inflammatory drugs. Monitoring the health...

Wildlife resource management requires reliable, fast, and affordable methods of surveying wildlife populations to develop and adaptively adjust policies. Many methods are used to survey populations of large mammals, and thermal video from drones can yield high rates of detection over large extents with relative speed and safety. In wild populations...

Due to Andean bears' propensity for inhabiting challenging environments and terrain, their wild ecology remains poorly understood, especially when compared to other members of the Ursidae family. In one of the steepest, wettest regions of the Andes, the Kosñipata Valley of southeastern Peru, we attached and retrieved camera‐borne collars on three w...

Tree cavities are an important ecological component of forests, used by animals for roosting, foraging, hunting, nesting, hiding, and hibernating. However, there has been a taxonomic bias toward investigating cavity use by birds, and a geographical bias toward temperate regions. We used camera traps to understand mammal cavity use in a tropical rai...

Corridors are essential tools for promoting biodiversity resilience under climate change. However, corridor design studies are often conducted at spatial scales too coarse to guide implementation by local conservation practitioners. We mapped potential climate-resilient corridors linking lowland to highland protected areas within a highly biodivers...

The sparsity of post-translocation monitoring data for rehabilitated felids leaves a pressing gap in our current understanding of their integration into and use of novel landscapes. Remote monitoring tools such as GPS collars can provide crucial insights into animal movement behavior and habitat selection following translocation and assist in the d...

Climate adaptation corridors are widely recognized as important for promoting biodiversity resilience under climate change. Central America is part of the Mesoamerican biodiversity hotspot, but there have been no regional-scale analyses of potential climate adaptation corridors in Central America. We identified 2375 potential corridors throughout C...

Understanding how diverse assemblages of scavengers can coexist on shared ecological resources is a fundamental challenge in community ecology. However, current approaches typically focus on behaviour at carcass provisioning sites, missing how important differences in movement behaviour and foraging strategies can facilitate sympatric species coexi...

While protected areas (PAs) are an important conservation strategy to protect vulnerable ecosystems and species, recent analyses question their effectiveness in curbing deforestation and maintaining landscape connectivity. The spatial arrangement of forests inside and outside of PAs may affect ecosystem functioning and wildlife movement. The Osa Pe...

Global sea turtle populations are in decline and so a global network of sea turtle nesting conservation programs have been established worldwide with the goal to protect vulnerable nesting mothers, and their clutches of eggs. Yet researchers have recently estimated that sea turtle nesting habitat is likely to suffer as a result of climate change an...

Habitat loss and fragmentation are primary threats to mammals in the Amazon. In this chapter, we review the extent of forest loss and fragmentation, the drivers of such processes, and the impacts on mammal species that have part of their geographic range within the Amazon. Land cover change due to pressures associated with agriculture, cattle, mini...

Understanding animal movements is vital for gaining insights into species' ecological patterns , habitat preferences, and reproductive strategies. Studies in dendrobatid frogs have revealed that home range behaviours, particularly in species with male parental care, are closely linked to the distribution of reproductive resources. Here we focus on...

A description of the Osa Biological Station, the wider campus and reserve, and the biodiversity and research from the site.

As biodiversity declines and climate change causes shifts in species distribution, the knowledge of species’ ecological needs is vital to conserve biodiversity. On Costa Rica’s Osa Peninsula and its adjacent forests, a rich mosaic of ecosystems hosting numerous threatened and endemic species, conservationists lack clarity on the basic habitat requi...

1. Understanding how diverse assemblages of scavengers can coexist on shared ecological resources is a fundamental challenge in community ecology. However, current approaches typically focus on behaviour at carcass provisioning sites, missing how important differences in movement behaviour and foraging strategies can facilitate sympatric species co...

Habitat encroachment can have devastating effects upon biodiversity, especially amphibians. Phyllobates vittatus is an endemic frog from Costa Rica, where land cover has seen significant changes over recent decades. Here we use remote sensing to create a land cover map of the region and carry out ecological niche modelling to identify the main abio...

Camera-traps have become one of the most common tools for studying wildlife abundance and population density. Traditionally, absolute density could be estimated only for species with individual markings, using capture–recapture frameworks. Newer methods allow to estimate density of unmarked species, but these have yet to be thoroughly tested and co...

As more land is altered by human activity and more species become at risk of extinction, it is essential that we understand the requirements for conserving threatened species across human-modified landscapes. Owing to their rarity and often sparse distributions, threatened species can be difficult to study and efficient methods to sample them acros...

The elusive Greater Grison has been reported to predate mostly relatively small prey, with evidence of some larger items. Using observations from cell phones and social media I report two separate predation events by Grison (Galictis vittata) upon its largest known prey to date, the Paca (Cuniculus paca); both events in Costa Rica. These observatio...

The Amazon is one of the most diverse biomes around the globe, currently threatened by economic and industrial development and climate change. Large mammals are keystone species, playing an important role in ecosystem structure and function as ecological engineers, while being highly susceptible to deforestation, habitat degradation , and human exp...

Identifying the mechanisms for seed dispersal and persistence of species is a central aim of ecology. Seed dispersal by animals is an essential form of dissemination in many plant communities, including seeds of over 66% of neotropical canopy tree species. 1 ,2 Besides physical dispersal, animals influence seed germination probabilities through sca...

1. Fluctuations in the diel cycle, especially when compared across different land-use types, can reveal key changes in acoustic activity and the biological community. Yet few studies have assessed the effects of land use change on soundscapes across the diel cycle. The emergence of passive acoustic monitoring (PAM) allows us to monitor landscapes o...

The efficacy of protected areas is tied to the management of surrounding areas. Still, the importance of buffer zones for biodiversity conservation is overlooked. Manu Biosphere Reserve is one of the most biodiverse places on earth, yet destructive land-use practices are degrading the ecological integrity of its buffer zone. To better understand th...

The payload size and commercial availability of thermal infrared cameras mounted on drones has initiated a new wave in the potential for conservationists and researchers to survey , count and detect wildlife, even the most complex of habitats such as forest canopies. However, several fundamental design and methodological questions remain to be test...

Linear infrastructures, especially roads, affect the integrity of natural habitats worldwide. Roads act as a barrier to animal movement, cause mortality, decrease gene flow and increase the probability of local extinctions, particularly for arboreal species. Arboreal wildlife bridges increase connectivity of fragmented forests by allowing wildlife...

Effective forest restoration requires tools for evaluating and comparing restoration approaches. Nevertheless, measuring restoration progress can be difficult and expensive. Passive acoustic monitoring (PAM) can be an inexpensive assessment strategy to collect large amounts of biodiversity information at scale. Nevertheless, analyzing and interpret...

Understanding how human modification of the landscape shapes vertebrate community composition is vital to understanding the current status and future trajectory of wildlife. Using a participatory approach, we deployed the largest camera-trap network in Mesoamer-ica to date to investigate how anthropogenic disturbance shapes the occupancy and co-occ...

Termites are a protein-rich yet unpredictable and ephemeral food source known to attract a diversity of reptiles, mammals, and birds. Here we provide the first observation of birds feeding on an explosion of winged termites swarming through the canopy in Western Amazonia in Peru. During this observation made from the canopy, at least 11 canopy-dwel...

Arboreal camera trapping is a burgeoning method providing a novel and effective technique to answer research questions across a variety of ecosystems, and it has the capacity to improve our understanding of a wide range of taxa. However, while terrestrial camera trapping has received much attention, there is little guidance for dealing with the uni...

Introduction: Background and Research Aims Assessing biodiversity recovery is key to determine whether the objectives of habitat restoration for conservation are met. Many restoration initiatives use cross-sectional comparisons of wildlife communities to infer restoration impact instead of longitudinal assessments from a baseline state. Using an in...

Riparian zones are one of the most productive ecosystems in the world, but are at risk due to agricultural expansion and climate change. To maximize return on conservation investment in mixed-use landscapes, it is important to identify the minimum intact riparian forest buffer sizes to conserve riparian ecosystem services. The minimum riparian fore...

• Dung beetles are frequently used to assess tropical biodiversity patterns and recovery in human‐modified forests. We conducted a comprehensive dung beetle survey (coprophagous and necrophagous communities) within five habitat types, across a land‐use gradient, in the ecologically biodiverse Osa Peninsula, located in Costa Rica's south Pacific. •...

The Osa Peninsula of southwest Costa Rica is home to the largest remaining tract of Pacific lowland wet forest in Mesoamerica. It is comprised of old and secondary growth seasonal tropical forest, and many other habitat types. The Geoffroy’s spider monkey is an endangered primate and an important disperser of large-seeded hardwood trees. One way in...

The Neotropical otter (Lontra longicaudis) is listed as Near Threatened by the IUCN, which describes the standardization of field survey techniques and identification of key habitats as two research priorities. Basic ecological information such as habitat selection and diet is also lacking, especially in Central America. Using surveys for tracks an...

Simple Summary Spider monkeys are important dispersers of many hardwood trees that contribute greatly to the carbon sequestration of tropical forests. One way in which Spider monkeys influence tropical ecosystem structure and function is through the creation of visible terrestrial latrines beneath their “sleeping sites”—trees in which they frequent...

Field Guide

Field guide of the bats of the Golfo Dulce region, Costa Rica.

The Amazonian poison frog genus Ameerega is one of the largest yet most understudied of the brightly colored genera in the anuran family Dendrobatidae, with 30 described species ranging throughout tropical South America. Phylogenetic analyses of Ameerega are highly discordant, lacking consistency due to variation in data types and methods, and ofte...

Biodiversity research along altitudinal gradients can provide us with new insights into conservation and human impacts. In this context, amphibians are a useful and important group due to their rapid response to environmental changes, severely threatened status and because of the gaps in our knowledge of their ecology, especially in tropical forest...

The Cerros del Sira in Peru is known to hold a diverse composition of endemic birds, amphibians and plants as a result of its geographical isolation, yet its mammalian community remains poorly known. There is increasing awareness of the threats to high-elevation species but studying them is often hindered by rugged terrain. We present the first cam...

Euspondylus excelsum was described from 8 specimens from the Region Huánuco in central Peru. We obtained an adult female from the Region Junín and a subadult male (photo vouchers only) from the Region Madre de Dios. Our new records of E. excelsum extend the range of this species by 592 km to the south and increase the previously known elevational r...

Deforestation and hunting are the leading human-driven disturbances causing population declines of the vulnerable Great Curassow (Crax rubra) and the near threatened Great Tinamou (Tinamus major). These threats typically co-occur, with synergistic effects. We investigated habitat use of Great Curassows and Great Tinamous in the Matapalo corridor of...

Accurately assessing how biodiversity responds in the Anthropocene is vital. To do so, a number of indicator taxa are commonly used to monitor human-impacted forests and the subsequent recovery of their biodiversity. This makes monitoring more economically feasible, yet only valuable if the responses observed truly reflect the status of biodiversit...

Tropical forests have, and in many areas continue to experience both severe and subtle forms of human disturbance; most commonly from hunting, logging and clearance for agriculture. The ability to detect a full range of impacts is essential to understanding how biodiversity responds to human disturbance. Since monitoring the entire biodiversity of...

The need to complement primary forest protection with the conservation of regenerating tropical forest is becoming increasingly well-understood. However, the persistence of biodiversity differences between areas once subjected to different anthropogenic land-uses, after long periods of regeneration, remains poorly understood. We investigate long-te...

Anuran attempted predation event.

The only known population of Sira curassow Pauxi koepckeae resides within the Sira Communal Reserve, a chain of isolated and high-elevation outcrops of the Peruvian Andes. The species has previously been detected on just a handful of occasions, is thought to number less than 400 adult individuals and is Critically Endangered according to the Intern...

We describe and name a new species of poison-dart frog from the Amazonian slopes of the Andes in Manu Province, Madre de Dios Department, Peru; specifically within the Amarakaeri Communal Reserve and the buffer zone of Manu National Park. Ameerega shihuemoy sp. nov. is supported by a unique combination of characters: black dorsum with cream to ligh...

A bilingual Spanish/English field guide for amphibians in southeast Peru. The Manu Biosphere Reserve is regarded as the most biodiverse place in the world for amphibians; and so the team wanted to produce a free resource to share this diversity with both a local and an international audience. It contains over 110 species of amphibian found within t...

Field Guide to the Reptile of the Cerros del Sira

Field guide to the Amphibians of the Cerros del Sira

Field observations on the reproductive biology of squamate reptiles are important to understanding the life history, ecology, and evolution of this diverse group (Vitt 1991, Ramírez-Bautista et al. 2000, Vitt et al. 2001, Werneck et al. 2009); however, these data remain sparse for many tropical species (Figueroa et al. 2013, Sousa et al. 2014). Sea...

Primates are important seed dispersers in tropical rainforest and it, is important to know how large primates response to habitat modification; especially their food requirements and resources. Groups of the little-known Peruvian woolly monkey in a regenerating rainforest of the Manu Biosphere Reserve displayed consumption of a wide variety (>100 s...

The lack of information about amphibians and reptiles in highly threatened tropical rainforest habitats has led to a need for innovative methods that can rapidly generate data on ecological behavior. The thread bobbin technique has proven successful for gathering ecological information in a range of habitats, but has not yet been used in tropical r...

A key part of tropical forest spatial complexity is the vertical stratification of biodiversity, with widely differing communities found in higher rainforest strata compared to terrestrial levels. Despite this, our understanding of how human disturbance may differentially affect biodiversity across vertical strata of tropical forests has been slow...

Matrix plot of factor scores for each of the three factors across survey sites, based upon the factor analysis of vegetation survey data. (TIF)

Dominance-diversity (Whittaker) plots for understorey, midstorey and canopy butterfly communities in regenerating rainforest with different disturbance histories; (a) overall, (b) understorey, (c) midstorey and (d) canopy. Species are represented by points. For each habitat the relative abundance of each species (ni/N) was plotted on a logarithmic...

Top model averaged coefficients (with shrinkage). (DOCX)

Beta similarity; measurements between strata for Morisita-Horn and Chao-Jaccard Estimated Abundance measures. (DOCX)

Moran’s index test results for spatio-autocorrelation; carried out on model residuals from the selected model for each response variable tested. (DOCX)

Average individuals per survey site of overall, understorey, midstorey and canopy strata of butterflies in regenerating rainforest with different disturbance histories, with standard error mean bars. (TIF)

Candidate models explaining variation in estimated species richness, Shannon diversity and abundance of butterflies, ranked according to increasing value of delta AICc. See S2 Text for top model averaged co-efficients. df = degrees of freedom; logLik = maximum log likelihood; delta AICc = AICci–AICcmin and weight = Akaike weights; + = inclusion wit...

Checklist of species detected. (DOCX)

The structure and underlying functions of the majority of the world’s tropical forests have been disrupted by human impacts, but the potential biodiversity and conservation value of regenerating forests is still debated. One review suggests that on average, regenerating tropical forests hold 57% (±2.6%) of primary forest species richness, raising d...