The research team, working across Italy, Switzerland and Germany, confronted a problem that has long troubled invasion biologists: control programmes are typically designed to maximise ecological and economic outcomes, while the welfare of the target animals is treated as an afterthought or ignored altogether. Recent work in conservation decision science has argued that animal welfare should be evaluated as an explicit objective alongside biodiversity benefits, so that trade-offs can be made transparently rather than by default. To do that for slider turtles, however, managers first need to know how much pain, distress or deprivation each technique actually causes, and for a reptile species, that evidence base is remarkably thin.

The study adapted the Five Domains framework, a widely used model in animal welfare science. Domain 1 covers nutrition, including food and water deprivation; Domain 2 covers environmental challenges such as heat, cold or lack of shelter; Domain 3 covers health, injury and disease; Domain 4 covers behavioural and social restrictions; and Domain 5 represents the overall mental consequence, the suffering that emerges from the first four domains. Building on an earlier Australian framework for assessing the humaneness of vertebrate pest control, the researchers defined eight management actions: capture with fyke or minnow traps, capture with basking traps, transportation in covered boxes, containment in semi-natural enclosures, containment in intensively managed facilities, shooting with a rifle, lethal injection, and freezing of eggs removed from wild nests.

Crucially, each action was assessed across explicit time intervals, a significant modification of the original framework. Trapping scenarios ranged from 12 hours to seven days depending on trap type, transportation from 3 to 24 hours, captivity from one year to more than a decade, and lethal methods from the instant of application to beyond 30 minutes until loss of consciousness. The underlying logic is that welfare impacts are not static: a turtle held briefly in a funnel trap may experience little more than behavioural unease, while one left for two days in warm water faces dehydration, overheating, aggression from other trapped individuals and escalating distress.

Because empirical data on turtle welfare barely exist, the team collated whatever evidence they could, including temperature logs and camera footage from field programmes in Hungary and Switzerland, necropsy records, husbandry guidelines and studies of embryonic development, and then turned to structured expert elicitation. Following a modified Delphi protocol, 24 experts scored the expected welfare impact of every action and timeframe on a five-step scale from No impact to Extreme, rating their own confidence after each answer. They then discussed anonymised results in multiple online rounds in English, German and Italian before revising their scores, a cycle designed to expose linguistic misunderstandings and prevent groupthink while preserving the diversity of judgement.

The results offer reassurance for well-run operations and warnings for sloppy ones. Experts broadly agreed that trapping causes no or mild suffering within the first 24 hours, and that transport of up to six hours at appropriate temperatures of 20 to 24 degrees Celsius is similarly benign. Intensively managed captivity, following husbandry standards developed in Italy, was judged to produce predominantly no or mild impacts even over many years. On the lethal side, all experts agreed that a properly placed rifle shot causing immediate loss of consciousness inflicts no suffering, and lethal injection with prior sedation was rated as causing none or mild suffering only. Egg freezing attracted relatively low impact estimates, on the reasoning that cold blocks nerve conduction, although the panel flagged that late-stage embryos, in which neural pathways may already be forming, remain a genuine uncertainty.

Time emerged as the single most important amplifier of harm. Statistical models confirmed that the probability of impacts reaching Moderate or Severe rose steadily, and often nearly linearly, with the duration of every action. Opinions diverged sharply beyond standard practice: once fyke traps were left unchecked beyond 24 hours, or basking traps beyond a few days, or transport stretched to 12 or 24 hours, some experts predicted Severe or even Extreme suffering. The greatest spread of opinion concerned semi-natural containment over decades, where overcrowding, disease transmission, poor water quality and the absence of veterinary care could accumulate into serious welfare decline, yet five of thirteen experts judged decade-long containment as Severe or Extreme while others remained far less concerned.

Expert confidence averaged a relatively high 80 percent overall, but it dropped in revealing patterns. Confidence was higher for non-lethal methods than for lethal ones, highest for transport and lowest for egg freezing, and it fell significantly as estimated impact levels increased and, after controlling for impact, over the longest timeframes. The weakest ground of all was Domain 4, behavioural and social welfare, where experts confessed that the inner states of a non-mammalian species are notoriously difficult to read. Veterinarians tended to rate impacts slightly higher than reptile specialists and caretakers, though the difference was not statistically significant, and their judgements were generally less polarised.

From the discussion rounds emerged a set of concrete best practices that managers can apply immediately. Traps should be checked at least every 24 hours for fyke traps and every three days for basking traps, and placed to offer shade and prevent overheating, with particular care around post-hibernation and breeding periods when densities and activity spike. Transport boxes should be compartmentalised or lined with cotton bags to maintain moisture, avoid mixing turtles of different sizes, and never exceed a few hours. Captive facilities must limit densities, provide varied microhabitats, basking sites, nesting opportunities and balanced diets, since inadequate nutrition is linked to bladder stones, shell deformities and ear infections in captive sliders. Shooting should only be performed by trained marksmen, and injection protocols must account for the ectothermic physiology of reptiles, whose slow metabolism in cold or stressed animals can delay drug action, making verification of anaesthesia, for example by testing the corneal reflex, essential before administering lethal agents.

The authors are careful to note that their findings reflect expert opinion rather than experimental proof, and that they assessed individual welfare only, leaving aside bycatch, multi-step interventions and the numbers of animals affected. Even so, the study demonstrates that formal elicitation can convert scattered, partly intuitive knowledge into a transparent and reproducible baseline for policy, showing decision-makers exactly where consensus is strong and where ignorance reigns. It also identifies where new research would pay off fastest: field studies quantifying first-shot success and time to insensibility in shooting, longitudinal comparisons of captivity facilities, and developmental work on when reptile embryos become capable of sensing pain. As invasive species management intensifies worldwide under pressure from biodiversity loss, the lesson from the humble slider turtle is that conservation and compassion need not be adversaries, provided the welfare costs of every capture, journey and end-point are counted honestly and minimised by design.

Subject of Research: Animal welfare assessment of lethal and non-lethal management methods for invasive slider turtles

Article Title: Animal welfare implications of management strategies for invasive freshwater turtles

Article References: Moser, L. A., Smith, B. R., Matthys, S., Kenup, C., Spongano, I., Cavatoni, S., Dal Zotto, M., Ferrari, N., Ferri, V., Hoby, S., Lloyd Jr., R. B., Moretti, A., Oneto, F., Origgi, F., Ottonello, D., Santicchia, F., Zanirato, N., Zuffi, M. A. L., & Canessa, S. (2026). Animal welfare implications of management strategies for invasive freshwater turtles. NeoBiota, 109, 345-366. https://doi.org/10.3897/neobiota.109.204683

Image Credits: AI Generated

DOI: 10.3897/neobiota.109.204683

Keywords: invasive species, Trachemys scripta, animal welfare, Five Domains framework, expert elicitation, herpetology, conservation management, euthanasia, reptile welfare, trapping, captivity, Delphi method

Researchers Rhiannon Schultz of Animal Welfare Expertise and the University of Georgia, Isabella Clegg of Animal Welfare Expertise, and Roberta Salmi of the University of Georgia observed 21 male western lowland gorillas at five Association of Zoos and Aquariums-accredited institutions in the United States. The subjects ranged from five to forty years old and fell into four groups: adolescents, pubescents, healthy adults, and adults diagnosed with cardiovascular disease, a condition that disproportionately affects male gorillas in zoos and was included because reduced activity levels in heart-diseased animals might influence abnormal behavior. Over the period from May 2023 to January 2025, the team logged 1,034 hours of direct behavioral observation, using focal animal sampling and instantaneous scans at five-minute intervals to build detailed daily activity budgets for each individual.

The scale of observation matters, because previous studies of R&R often relied on small samples or on surveys of caretaker recollections rather than direct recording. By watching the animals themselves, the researchers could capture what happened immediately before each regurgitation event, what the animal had eaten beforehand, and how the behavior clustered in time. They also went beyond behavior into chemistry, analyzing the nutrient composition of the foods most often brought back up, using USDA databases and laboratory proximate analysis of dehydrated samples that measured crude protein, neutral detergent fiber, gross energy, and mineral content.

The results revealed a striking temporal pattern. R&R was overwhelmingly an afternoon affair. The statistical models showed the probability of the behavior at its lowest during the early morning hours of six to nine a.m., creeping upward through midday and peaking between three and six p.m. Even more telling was the relationship with feeding: the more time a gorilla spent feeding on a given day, the less likely it was to engage in R&R at all. This inverse correlation fits a hypothesis the researchers had set out to test, that the behavior may function as a way of extending feeding time when captive diets fail to satisfy the drives that wild feeding patterns normally fulfill.

That mismatch between wild and captive feeding is dramatic. Wild gorillas spend forty to fifty percent of their waking hours feeding and foraging on fibrous plant material, while zoo-housed gorillas dedicate at most twenty to twenty-five percent of their time to eating. Captive diets are nutrient-dense and low in fiber, meaning animals can consume their entire daily ration in a fraction of the time it would take to meet equivalent needs in a forest. The new study adds nuance to this picture: gorillas who structured their eating into longer, consolidated bouts followed by long gaps of inactivity showed higher R&R frequencies, while those with more fragmented feeding opportunities showed less. The behavior, in other words, appears tied not just to how much an animal eats, but to the rhythm of eating across the day.

The food chemistry results were perhaps the most surprising. Caretakers have long blamed fruit, with its sugar content and palatability, as the main trigger for R&R, and reduced-fruit diets have sometimes appeared to help. But this study found that commercial primate chow topped the list of foods disproportionately associated with the behavior, followed by fruit juice, grapes, cabbage, mixed nuts, and carrots. Only sycamore among the browse items was significant. Meanwhile, banana, broccoli, kale, and popcorn showed no association at all. Permutation-based nutrient comparisons showed that regurgitated foods tended to be richer in phosphorus, potassium, calcium, and magnesium, while fiber’s role proved more complicated than expected: some of the most regurgitated items, like chow and sycamore browse, were actually high in fiber.

The category-level analysis sharpened the contrast. Root vegetables carried more than a sixfold increase in the likelihood of being regurgitated relative to the baseline, chow and biscuits more than tripled the risk, and nuts, enrichment foods, and fruit each roughly doubled it. Browse, by contrast, was dramatically underrepresented: gorillas were about ninety-seven percent less likely to regurgitate browse than the reference category. Because browse items like leaves and stems demand long processing and chewing time, this finding suggests that foods requiring extended handling may protect against the behavior, while foods that can be gulped down quickly may leave the feeding drive unsatisfied. The researchers note that individual variation was considerable, with one gorilla regurgitating disproportionately after cabbage and another after oatmeal, suggesting diet design should work at the level of specific items rather than broad categories.

The behavioral sequence analysis revealed something equally important: R&R is not one uniform behavior but appears to come in at least two distinct forms. Isolated single events tended to follow periods of rest and inactivity, especially after sequences of resting followed by feeding, consistent with the old hypothesis that boredom or unmet foraging motivation triggers the behavior. Clustered bouts, in which animals repeated the cycle many times, were instead closely tied to feeding episodes, and only feeding occurred in the thirty-minute window preceding R&R episodes. A logistic decision-tree model identified high-risk sequences such as feeding transitioning into prolonged inactivity, and found that R&R itself predicted future R&R, hinting that in some individuals the behavior becomes self-reinforcing and potentially stereotypic.

Demographic patterns added another layer of intrigue, even if they were not statistically conclusive. Adults with heart disease showed the highest average time spent in R&R at about eighty minutes, and pubescents also showed elevated rates, though the study found no significant effect of demographic group overall and individual variability was high. The authors speculate that R&R may relate to metabolic or energetic demands that standard zoo diets, typically calculated from body weight, do not capture, particularly during growth or physiological change. They connect this to a broader metabolic picture: captive gorillas share risk factors with humans diagnosed with metabolic syndrome, including energy-dense, low-fiber diets, and these factors have been implicated in fibrosing cardiomyopathy, the leading heart disease of male zoo gorillas.

The practical implications are concrete. The authors suggest that breaking the day into more frequent, smaller feeding opportunities, ideally accompanied by low-sodium browse such as pear, American beech, or hackberry, could disrupt the long-bout-then-long-gap pattern that breeds clustered R&R. Predictive behavioral monitoring could flag risk windows in real time, allowing keepers to deploy enrichment or social opportunities before abnormal behavior emerges. The researchers caution that their study was observational and cannot establish causation, that physiological measures of hunger and satiety were not assessed, and that the sample, though larger than most previous work, was limited to males. Still, by dissecting R&R at the level of events, bouts, and episodes, and pairing behavior with nutrient chemistry, the study reframes this peculiar habit not as a meaningless quirk of captive life, but as a window into how environment and diet reshape the inner signals of hunger, fullness, and boredom in one of our closest relatives.

Subject of Research: Regurgitation and reingestion behavior in captive male western lowland gorillas and its dietary and behavioral triggers

Article Title: Abnormal ingestive behavior in male zoo gorillas: investigating the dietary and activity patterns associated with regurgitation and reingestion

Article References: Schultz, R. L., Clegg, I. L. K., & Salmi, R. (2026). Abnormal ingestive behavior in male zoo gorillas: investigating the dietary and activity patterns associated with regurgitation and reingestion. Frontiers in Ethology, 5, Article 1896803. https://doi.org/10.3389/fetho.2026.1896803

Image Credits: AI Generated

DOI: 10.3389/fetho.2026.1896803

Keywords: gorillas, animal welfare, regurgitation and reingestion, zoo nutrition, abnormal behavior, stereotypies, primate chow, browse, satiety, feeding behavior, captivity, ethology

The researchers designed controlled feeding experiments in which wild-caught and captive lizards were compared under standardized conditions, with some captive animals maintained on different insect diets, including mealworms and mixed mealworm-cockroach rations. Fecal and physiological samples were then interrogated with two complementary high-throughput approaches. Sequencing of the 16S ribosomal RNA gene provided a census of the bacterial communities living in the gut, while metabolomic profiling mapped the small molecules circulating through the animals’ systems, revealing which biochemical pathways were actually active. Digestive enzyme assays and blood parameters completed the picture, connecting microbial and metabolic shifts to measurable differences in how the lizards process food and defend their tissues from oxidative damage.

The microbial census revealed a core gut community shared by all groups, dominated by three bacterial phyla that are also mainstays of vertebrate gut microbiomes generally: Firmicutes, Bacteroidetes and Proteobacteria. But the interesting biology emerged in the differences at the margins. Wild lizards carried enriched populations of Verrucomicrobia, a phylum often associated with the degradation of complex polysaccharides and the maintenance of gut barrier function. Captive animals fed mealworms, by contrast, showed increased abundances of Fusobacteria, a group whose expansion in captive and carnivore-adjacent diets has been noted in other reptile studies. These compositional shifts suggest that even within a shared core community, the specific ecological conditions of the gut, shaped by diet and environment, select for distinct microbial specialists.

Diversity metrics told a subtler story. Captivity significantly reduced the overall diversity of the gut microbiota, a pattern consistent with the idea that a monotonous captive diet and a simplified environment prune the microbial ecosystem down to a narrower set of taxa. Interestingly, when the authors examined alpha-diversity indices individually, captivity significantly affected the Chao1 index, which estimates species richness, but the other alpha-diversity measures did not differ significantly between groups. Community structure, however, was clearly altered, meaning that the identity and relative abundance of the microbes present shifted in ways that raw richness counts alone could not capture. This distinction between richness and composition matters for anyone designing captive husbandry protocols, because a gut can look statistically similar in one metric while hosting a functionally different microbial workforce.

Metabolomics added a functional layer to the microbial story. Wild lizards displayed higher overall metabolic activity, with significant enrichment of amino acid metabolism and linoleic acid metabolism pathways. Linoleic acid, an essential omega-6 fatty acid, sits at the hub of pathways governing membrane fluidity, inflammatory signaling and energy storage, so its enhanced processing in wild animals hints at a metabolic flexibility tuned to the variable, resource-poor desert diet. Amino acid metabolism, meanwhile, reflects the constant turnover of proteins that fuels tissue repair, immune function and nitrogen balance. In contrast, lizards fed a 1:1 mixture of mealworms and cockroaches showed altered lysine degradation, indicating that even carefully composed captive diets redirect the flow of nitrogen and carbon through the body in ways that differ from the wild state.

The physiological assays translated these molecular differences into concrete digestive and immune phenotypes. Wild lizards exhibited higher activities of alpha-amylase and cellulase, enzymes that break down starch and plant-derived structural carbohydrates respectively. Elevated cellulase activity in wild animals is particularly striking, because it implies that free-ranging geckos encounter and exploit plant material or gut contents of prey that captive diets simply do not provide. Captive lizards on a high-protein insect diet showed the opposite pattern: elevated trypsin activity, the key pancreatic protease, reflecting a digestive system recalibrated to a protein-rich, carbohydrate-poor menu. In effect, the gut of a captive gecko becomes a specialist in protein digestion, while its wild counterpart retains a broader enzymatic toolkit.

Blood-based measurements revealed divergences in immune status and oxidative stress management. Captive lizards had higher leukocyte counts, which can indicate heightened immune activation, whether in response to the stress of confinement, exposure to novel pathogens in the captive environment or inflammatory signals arising from an altered gut microbiome. Wild lizards, on the other hand, demonstrated higher antioxidant capacity, suggesting a more robust system for neutralizing the reactive oxygen species generated during intense activity, thermoregulation and foraging in a harsh desert environment. Taken together, these trends sketch two distinct physiological profiles: a captive animal with an activated but potentially less resilient immune-metabolic state, and a wild animal with a metabolism and antioxidant defense tuned to the demands of life in the Turpan Depression.

Why does this matter for conservation and animal welfare? Captive breeding and head-starting programs are increasingly central to protecting reptiles threatened by habitat loss, climate change and collection for the pet trade. Yet the ultimate goal of such programs is usually to produce animals capable of surviving in the wild. If captivity systematically erodes gut microbial diversity, redirects metabolic pathways and reshapes digestive enzyme profiles, then released animals may face a double burden: adapting to a new environment while simultaneously rebuilding an internal ecosystem that captivity has simplified. The authors frame their work as providing a theoretical basis for host health management under captive conditions, and the practical message is clear that diet composition and environmental complexity in captivity leave measurable molecular fingerprints that managers can now monitor.

The study also contributes to a growing scientific appreciation of reptile gut microbiomes as dynamic, diet-responsive ecosystems rather than fixed appendages of host biology. Desert lizards like T. roborowskii endure extreme thermal fluctuations, scarce and unpredictable food resources, and water stress, conditions that likely select for both flexible host physiology and a versatile microbial community. The enrichment of Verrucomicrobia in wild animals and the metabolic signatures of enhanced lipid and amino acid processing suggest that the wild gut is a biochemically busier place, processing a wider array of substrates. Captivity, by flattening dietary and environmental variation, appears to flatten this internal diversity as well.

Looking forward, the multi-omics framework deployed here, pairing microbial census data with metabolomics and enzyme physiology, offers a template that could be applied to other captive-wild comparisons across taxa, from amphibians to birds to mammals. The open-access publication, released in August 2026 with a permanent DOI, makes the full dataset available to researchers worldwide. For the geckos of Xinjiang’s deserts, the study is a reminder that adaptation is written not only in the genome of the host but in the trillions of microbes it carries, and that preserving a species means preserving the invisible ecosystem within it. For captive animal managers everywhere, it is a call to design husbandry that feeds not just the animal, but its microbiome.

Subject of Research: Effects of captivity on gut microbiota, metabolomics and physiology of the desert gecko Teratoscincus roborowskii

Article Title: Comprehensive evaluation of environmental adaptability in wild and captive Teratoscincus roborowskii: gut microbiota, metabolomic profiles, and physiology

Article References: Feng, H., Yang, Y., Wu, R., Wu, X., Huang, S., Zheng, Y., Yang, Q., & Ding, N. (2026). Comprehensive evaluation of environmental adaptability in wild and captive Teratoscincus roborowskii: gut microbiota, metabolomic profiles, and physiology. BMC Genomics. https://doi.org/10.1186/s12864-026-13316-3

Image Credits: AI Generated

DOI: 10.1186/s12864-026-13316-3

Keywords: Teratoscincus roborowskii, gut microbiota, metabolomics, 16S rRNA sequencing, captivity, digestive enzymes, desert lizard, antioxidant capacity, conservation breeding, animal physiology, BMC Genomics, Xinjiang