Detection of Ophidiomyces and Nannizziopsis spp. in the dermal lesions of free-roaming native snakes in Taiwan

Chrysosporium-related fungi refers to an assemblage of fungi belonging to the Nannizziopsis, Ophidiomyces, and Paranannizziopsis genera. Chrysosporium-related fungi infection results in various skin lesions, such as necrosis and ulcers, in both captive and free-roaming reptiles. To update the prevalence of ophidiomycosis in Taiwan, which was first detected in 2019, we conducted a large-scale ecological survey of free-roaming native snakes with skin lesions in Taiwan. To the best of our knowledge, this is the first study on Chrysosporium-related fungi prevalence in Southeast Asia. Fungal samples collected from the skin lesions of snakes were cultured and subjected to morphological, histopathological, and molecular analyses. We examined 2382 free-roaming snakes representing 42 snake species; among them, 132 (5.54%) had skin lesions. Ten (0.42%) snakes, representing four species, tested positive for Ophidiomyces (five snakes, four species) or a possibly novel Nannizziopsis species (five snakes, three species). The infected snakes were generally healthy, with mild clinical signs. The low prevalence rate, mild clinical signs, and broad pathogen/host range suggest that Ophidiomyces and Nannizziopsis are endemic to Southeast Asia. The newly reported presence of Nannizziopsis in free-roaming snakes suggests the need for modifying the currently used surveillance strategy.

Challenges in rescuing snakes to protect human lives and promote snake conservation in Tamil Nadu, India

BACKGROUND

Human-snake conflicts are common worldwide, often resulting in snakebites. Snakebite envenoming causes over 125,000 deaths and 400,000 permanent disabilities worldwide every year. India alone accounts for an average of ~58,000 annual snakebite-induced deaths. As human developments rapidly expand into suburban and rural areas, snakes are being displaced and incidences of residents finding snakes within their dwellings are increasing. Most people have an innate fear of snakes, compounded by centuries of negative influence from culture and mythology manifesting in people often attempting to kill snakes. Snake rescuers are volunteers who remove and relocate snakes to safe areas. This is a risky job that poses potentially fatal implications if bitten. These volunteers mostly receive no financial compensation for their time or transportation costs, but they choose to do it for their love of snakes, conservation, and for the altruistic nature of helping others. Snake rescuers often receive no formal training and are unfunded resulting in removing snakes improperly without adequate safety equipment or the required skill set to safely complete the task. Therefore, it is critical to determine their challenges and requirements to promote the safe rescue of snakes while protecting human lives.

METHODOLOGY/PRINCIPAL FINDINGS

In this study, we developed an online questionnaire and interviewed 152 snake rescuers in Tamil Nadu, India following written informed consent to determine their challenges and needs for rescuing snakes safely. The results demonstrate that most rescuers are males, and they conduct snake rescues for varying lengths of time. They mostly receive no formal training and are bitten by snakes. They spend their own money on the purchase of snake-handling equipment and on treatments if bitten or injured during a rescue.

CONCLUSIONS/SIGNIFICANCE

The rescuers highlighted the urgent need for formal training, safety equipment and standard protocols for rescuing snakes in Tamil Nadu. Overall, this study demonstrates that snake rescuing should be appropriately regulated by the authorities, in particular the Wildlife Division of State Forest Departments in India, and formal training along with necessary equipment, medical insurance and appropriate recognition should be provided to them to safely remove snakes from human dwellings and manage the safety of both snakes and humans. They can also act as educators to disseminate information about the preventive and first aid measures for snakebites as well as the ecological importance of snakes.

The fitness consequences of wildlife conservation translocations: a meta-analysis

Conservation translocation is a common strategy to offset mounting rates of population declines through the transfer of captive- or wild-origin organisms into areas where conspecific populations are imperilled or completely extirpated. Translocations that supplement existing populations are referred to as reinforcements and can be conducted using captive-origin animals [ex situ reinforcement (ESR)] or wild-origin animals without any captive ancestry [in situ reinforcement (ISR)]. These programs have been criticized for low success rates and husbandry practices that produce individuals with genetic and performance deficits, but the post-release performance of captive-origin or wild-origin translocated groups has not been systematically reviewed to quantify success relative to wild-resident control groups. To assess the disparity in post-release performance of translocated organisms relative to wild-resident conspecifics and examine the association of performance disparity with organismal and methodological factors across studies, we conducted a systematic review and meta-analysis of 821 performance comparisons from 171 studies representing nine animal classes (101 species). We found that translocated organisms have 64% decreased odds of out-performing their wild-resident counterparts, supporting claims of systemic issues hampering conservation translocations. To help identify translocation practices that could maximize program success in the future, we further quantified the impact of broad organismal and methodological factors on the disparity between translocated and wild-resident conspecific performance. Pre-release animal enrichment significantly reduced performance disparities, whereas our results suggest no overall effects of taxonomic group, sex, captive generation time, or the type of fitness surrogate measured. This work is the most comprehensive systematic review to date of animal conservation translocations in which wild conspecifics were used as comparators, thereby facilitating an evaluation of the overall impact of this conservation strategy and identifying specific actions to increase success. Our review highlights the need for conservation managers to include both sympatric and allopatric wild-reference groups to ensure the post-release performance of translocated animals can be evaluated. Further, our analyses identify pre-release animal enrichment as a particular strategy for improving the outcomes of animal conservation translocations, and demonstrate how meta-analysis can be used to identify implementation choices that maximize translocated animal contributions to recipient population growth and viability.

The Reptile Relocation Industry in Australia: Perspectives from Operators

Thousands of reptiles are relocated annually in Australia, yet there has been relatively little research aimed at understanding how the reptile relocation industry operates. An online questionnaire was distributed to anyone who had relocated a reptile between April 2019 and April 2020, including wildlife relocators, wildlife rehabilitators and the general public. The questionnaire explored demographics, decision-making and concerns about how the industry functions, through 24 questions and two opportunities to provide open-ended comments. We received 125 responses and 123 comments from operators in all Australian states and territories. Beliefs about appropriate times and places for reptile releases were not reflected in practice for the majority of operators. Confidence about reptiles remaining at recipient sites was low regardless of how many years’ experience an operator had. Escaped captive native reptiles were encountered by most operators, and a quarter of operators were called out to exotic non-native snakes. Operators across all levels of experience indicated a need for changes within the industry, including increased training and professionalism, and more scientific studies on the outcomes of relocations to address concerns about the impacts that the industry has on the wildlife that it is trying to protect.

Malayan kraits (Bungarus candidus) show affinity to anthropogenic structures in a human dominated landscape

Animal movement can impact human-wildlife conflict by influencing encounter and detection rates. We assess the movement and space use of the highly venomous and medically important Malayan krait (Bungarus candidus) on a suburban university campus. We radio-tracked 14 kraits for an average of 114 days (min: 19, max: 218), during which we located individuals an average of 106 times (min: 21, max: 229) each. Most individuals displayed some level of attraction to buildings (n = 10) and natural areas (n = 12); we identified a similar unambiguous pattern of attraction to buildings and natural areas at the population level (of our sample). Snakes remained in shelter sites for long durations (max: 94 days) and revisited sites on average every 15.45 days. Over 50% of locations were within human settlements and 37.1% were associated with buildings. We found generally seasonal patterns of activity, with higher activity in wet seasons, and lower activity in the hot season. These results show frequent proximity between Malayan kraits and humans at the university; thereby, suggesting a near constant potential for human-wildlife conflict. Despite the fact that no snakebites from this species occurred at the university during our study period, substantial education and awareness training should be considered to ensure continued coexistence on campus.

Mitigation translocation as a management tool

Mitigation translocation is a subgroup of conservation translocation, categorized by a crisis-responsive time frame and the immediate goal of relocating individuals threatened with death. However, the relative successes of conservation translocations with longer time frames and broader metapopulation- and ecosystem-level considerations have been used to justify the continued implementation of mitigation translocations without adequate post hoc monitoring to confirm their effectiveness as a conservation tool. Mitigation translocations now outnumber other conservation translocations, and understanding the effectiveness of mitigation translocations is critical given limited global conservation funding especially if the mitigation translocations undermine biodiversity conservation by failing to save individuals. We assessed the effectiveness of mitigation translocations by conducting a quantitative review of the global literature. A total of 59 mitigation translocations were reviewed for their adherence to the adaptive scientific approach expected of other conservation translocations and for the testing of management options to continue improving techniques for the future. We found that mitigation translocations have not achieved their potential as an effective applied science. Most translocations focused predominantly on population establishment- and persistence-level questions, as is often seen in translocations more broadly, and less on metapopulation and ecosystem outcomes. Questions regarding the long-term impacts to the recipient ecosystem (12% of articles) and the carrying capacity of translocation sites (24% of articles) were addressed least often, despite these factors being more likely to influence ultimate success. Less than half (47%) of studies included comparison of different management techniques to facilitate practitioners selecting the most effective management actions for the future. To align mitigation translocations with the relative success of other conservation translocations, it is critical that future mitigation translocations conform to an established experimental approach to improve their effectiveness. Effective mitigation translocations will require significantly greater investment of time, expertise, and resources in the future.

Individual heterogeneity influences the effects of translocation on urban dispersal of an invasive reptile

BACKGROUND

Invasive reptiles pose a serious threat to global biodiversity, but early detection of individuals in an incipient population is often hindered by their cryptic nature, sporadic movements, and variation among individuals. Little is known about the mechanisms that affect the movement of these species, which limits our understanding of their dispersal. Our aim was to determine whether translocation or small-scale landscape features affect movement patterns of brown treesnakes (Boiga irregularis), a destructive invasive predator on the island of Guam.

METHODS

We conducted a field experiment to compare the movements of resident (control) snakes to those of snakes translocated from forests and urban areas into new urban habitats. We developed a Bayesian hierarchical model to analyze snake movement mechanisms and account for attributes unique to invasive reptiles by incorporating multiple behavioral states and individual heterogeneity in movement parameters.

RESULTS

We did not observe strong differences in mechanistic movement parameters (turning angle or step length) among experimental treatment groups. We found some evidence that translocated snakes from both forests and urban areas made longer movements than resident snakes, but variation among individuals within treatment groups weakened this effect. Snakes translocated from forests moved more frequently from pavement than those translocated from urban areas. Snakes translocated from urban areas moved less frequently from buildings than resident snakes. Resident snakes had high individual heterogeneity in movement probability.

CONCLUSIONS

Our approach to modeling movement improved our understanding of invasive reptile dispersal by allowing us to examine the mechanisms that influence their movement. We also demonstrated the importance of accounting for individual heterogeneity in population-level analyses, especially when management goals involve eradication of an invasive species.

Promoting co-existence between humans and venomous snakes through increasing the herpetological knowledge base

Snakebite incidence at least partly depends on the biology of the snakes involved. However, studies of snake biology have been largely neglected in favour of anthropic factors, with the exception of taxonomy, which has been recognised for some decades to affect the design of antivenoms. Despite this, within-species venom variation and the unpredictability of the correlation with antivenom cross-reactivity has continued to be problematic. Meanwhile, other aspects of snake biology, including behaviour, spatial ecology and activity patterns, distribution, and population demography, which can contribute to snakebite mitigation and prevention, remain underfunded and understudied. Here, we review the literature relevant to these aspects of snakebite and illustrate how demographic, spatial, and behavioural studies can improve our understanding of why snakebites occur and provide evidence for prevention strategies. We identify the large gaps that remain to be filled and urge that, in the future, data and relevant metadata be shared openly via public data repositories so that studies can be properly replicated and data used in future meta-analyses.

Climate change and the increase of human population will threaten conservation of Asian cobras

Asian cobras (genus Naja) are venomous snakes distributed from the Middle East to Southeast Asia. Because cobras often live near humans settlements, they are responsible for a large part of snakebite incidents and as such pose a challenge for public health systems. In the light of growing human populations, correctly mapping the present and future ranges of Asian cobras is therefore important for both biological conservation and public health management. Here, we mapped the potential climatic niches of ten Asian cobra species for both the present and the future, with the aim to quantify changes in climate and human population densities relative to their current and future ranges. Our analyses reveal that cobras that are adapted to dry climates and inhabit islands have narrow climatic niches, while those of mainland species with larger geographic ranges are much wider. We also found a higher degree of fragmentation of future cobra distributions; within the next 50 years, Asian cobras will lose an average of around 60% of their current suitable climatic range. In the near future, Naja mandalayensis, N. sputatrix, N. samarensis, and N. philippinensis are likely to have no accessible suitable climate space left. Besides, a further increase of human populations in this region may also exponentially accelerate the effects of anthropogenic impacts. Solutions for conservation may involve awareness and appropriate use of law to overcome the rate of habitat degradation and the increase of animal trade of Asian cobras, while promoting investment on health systems to avoid snakebite fatalities.

No room to roam: King Cobras reduce movement in agriculture

BACKGROUND

Studying animal movement provides insights into how animals react to land-use changes. As agriculture expands, we can use animal movement to examine how animals change their behaviour in response. Recent reviews show a tendency for mammalian species to reduce movements in response to increased human landscape modification, but reptile movements have not been as extensively studied.

METHODS

We examined movements of a large reptilian predator, the King Cobra (Ophiophagus hannah), in Northeast Thailand. We used a consistent regime of radio telemetry tracking to document movements across protected forest and adjacent agricultural areas. Using dynamic Brownian Bridge Movement Model derived motion variance, Integrated Step-Selection Functions, and metrics of site reuse, we examined how King Cobra movements changed in agricultural areas.

RESULTS

Motion variance values indicated that King Cobra movements increased in forested areas and tended to decrease in agricultural areas. Our Integrated Step-Selection Functions revealed that when moving in agricultural areas King Cobras restricted their movements to remain within vegetated semi-natural areas, often located along the banks of irrigation canals. Site reuse metrics of residency time and number of revisits appeared unaffected by distance to landscape features (forests, semi-natural areas, settlements, water bodies, and roads). Neither motion variance nor reuse metrics were consistently affected by the presence of threatening landscape features (e.g. roads, human settlements), suggesting that King Cobras will remain in close proximity to threats, provided habitat patches are available.

CONCLUSIONS

Although King Cobras displayed individual heterogeneity in their response to agricultural landscapes, the overall trend suggested reduced movements when faced with fragmented habitat patches embedded in an otherwise inhospitable land-use matrix. Movement reductions are consistent with findings for mammals and forest specialist species.

Reptiles on the wrong track? Moving beyond traditional estimators with dynamic Brownian Bridge Movement Models

BACKGROUND

Animal movement expressed through home ranges or space-use can offer insights into spatial and habitat requirements. However, different classes of estimation methods are currently instinctively applied to answer home range, space-use or movement-based research questions regardless of their widely varying outputs, directly impacting conclusions. Recent technological advances in animal tracking (GPS and satellite tags), have enabled new methods to quantify animal space-use and movement pathways, but so far have primarily targeted mammal and avian species.

METHODS

Most reptile spatial ecology studies only make use of two older home range estimation methods: Minimum Convex Polygons (MCP) and Kernel Density Estimators (KDE), particularly with the Least Squares Cross Validation (LSCV) and reference (h _ref ) bandwidth selection algorithms. These methods are frequently applied to answer space-use and movement-based questions. Reptile movement patterns are unique (e.g., low movement frequency, long stop-over periods), prompting investigation into whether newer movement-based methods -such as dynamic Brownian Bridge Movement Models (dBBMMs)- apply to Very High Frequency (VHF) radio-telemetry tracking data. We simulated movement data for three archetypical reptile species: a highly mobile active hunter, an ambush predator with long-distance moves and long-term sheltering periods, and an ambush predator with short-distance moves and short-term sheltering periods. We compared traditionally used estimators, MCP and KDE, with dBBMMs, across eight feasible VHF field sampling regimes for reptiles, varying from one data point every four daylight hours, to once per month.

RESULTS

Although originally designed for GPS tracking studies, dBBMMs outperformed MCPs and KDE h _ref across all tracking regimes in accurately revealing movement pathways, with only KDE LSCV performing comparably at some higher frequency sampling regimes. However, the LSCV algorithm failed to converge with these high-frequency regimes due to high site fidelity, and was unstable across sampling regimes, making its use problematic for species exhibiting long-term sheltering behaviours. We found that dBBMMs minimized the effect of individual variation, maintained low error rates balanced between omission (false negative) and commission (false positive), and performed comparatively well even under low frequency sampling regimes (e.g., once a month).

CONCLUSIONS

We recommend dBBMMs as a valuable alternative to MCP and KDE methods for reptile VHF telemetry data, for research questions associated with space-use and movement behaviours within the study period: they work under contemporary tracking protocols and provide more stable estimates. We demonstrate for the first time that dBBMMs can be applied confidently to low-resolution tracking data, while improving comparisons across regimes, individuals, and species.

SUPPLEMENTARY INFORMATION

Supplementary information accompanies this paper at 10.1186/s40462-020-00229-3.