Animal Behavior Research Articles

Nesting habitat characteristics and predation patterns in the European pond turtle Emys orbicularis (L., 1758): Implications for management and conservation measures

Integrating knowledge regarding habitat characteristics and animal behaviour into conservation programs has the potential to impact the results of management and conservation efforts. This study aimed to explore the relationship between spatial and environmental data on the nesting activity of the European pond turtle, Emys orbicularis. Additionally, it sought to analyse the abundance, activity pattern, and behaviour of potential nest predators of E. orbicularis. Natural predated nests of the European pond turtle were utilized to characterise nesting habitat features, while artificial nests and camera traps were deployed to identify potential predators and their behaviour. Artificial nests and camera traps were established in areas with evidence of track detection or historical observations indicating past instances of nest predation. The nest site distribution of the European pond turtle showed a positive relationship with north-south oriented canals, the presence of vegetative components on embankments (shrubs, grass, emergent vegetation), finer-grained soil components (silt and clay), and soil moisture. Camera trapping of artificial nests revealed mammals (Meles meles and Vulpes vulpes) and a bird (Pica pica) as predators engaging in digging and destroying behaviour. P. pica detection was notably higher in mowed vegetation areas. Results indicate that natural nest distribution and predation on artificial nests may be influenced by their distribution concerning human-controlled vegetation and foraging activities of common nest predators. Protecting nesting sites in predator-frequented habitats, combined with landscape management targeting vegetation control along embankments, could mitigate nest predation and enhance hatchling recruitment.

Simultaneous Dopamine and Serotonin Monitoring in Freely Moving Crayfish Using a Wireless Electrochemical Sensing System.

Dopamine (DA) and serotonin (5-HT) are neurotransmitters that regulate a wide range of physiological and behavioral processes. Monitoring of both neurotransmitters with real-time analysis offers important insight into the mechanisms that shape animal behavior. However, bioelectronic tools to simultaneously monitor DA and 5-HT interactive dynamics in freely moving animals are underdeveloped. This is mainly due to the limited sensor sensitivity with miniaturized electronics. Here, we present a semi-implantable electrochemical device achieved by integrating a multi-surface-modified carbon fiber microelectrode with a miniaturized potentiostat module to detect DA and 5-HT in vivo with high sensitivity and selectivity. Specifically, carbon fiber microelectrodes were modified through electrochemical treatment and surface coatings to improve sensitivity, selectivity, and antifouling properties. A customized, lightweight potentiostat module was developed for untethered electrochemical measurements. Integrated with the microelectrode, the microsystem is compact (2.8 × 2.3 × 2.1 cm) to minimize its impacts on animal behavior and achieved simultaneous detection of DA and 5-HT with sensitivities of 48.4 and 133.0 nA/μM, respectively, within submicromolar ranges. The system was attached to the crayfish dorsal carapace, allowing electrode implantation into the heart of a crayfish to monitor DA and 5-HT dynamics, followed by drug injections. The semi-implantable biosensor system displayed a significant increase in oxidation peak currents after DA and 5-HT injections. The device successfully demonstrated the application for in vivo simultaneous monitoring of DA and 5-HT in the hemolymph (i.e., blood) of freely behaving crayfish underwater, yielding a valuable experimental tool to expand our understanding of the comodulation of DA and 5-HT.

Behavioral, physiological, and hormonal responses during pre-slaughter handling in goats: A comparison between trained and untrained handlers.

The livestock handler attitude and their handling of animals is crucial for improving animal welfare standards, minimizing stress, improving productivity and meat quality. The present study was undertaken to assess the effect of training livestock handlers on behavioral, physiological, and hormonal responses during preslaughter handling in goats. A total of 6 handlers were divided into trained (trained in basic animal handling practices, animal behavior, and animal welfare), contact trained (not trained directly but interacted and saw the working of trained handlers), and untrained groups (no formal training). The handling experiment was conducted on 18 male goats by following a cross-over design. The goats were moved from lairage to slaughter point by trained, contact-trained, and untrained handlers. Various behavioral, physiological, and hormonal parameters were recorded at the lairage before handling and at the slaughter point after handling the goats. The training of livestock handlers had a significant effect on behavioral, physiological, and hormonal responses in goats. The goats handled by untrained and contact-trained handlers were recorded with intense vocalization, significant (p<0.05) increase in heart rate and blood glucose, and catecholamines (adrenaline and nor-adrenaline), thereby indicating stress and poor animal welfare. The trained handlers were observed to use visual interactions (waving of hands or objects, blocking, hand raising, etc), and lower stress responses were recorded in the goats handled by this group. The present study highlights the importance of training to livestock handlers in improving animal welfare and minimizing stress in goats during preslaughter stress.

A simple assay for measuring tannin-protein precipitation capacity offers insights into the diet and food choice of black howler monkeys (Alouatta pigra).

Phenolics, like tannins, are plant-specialized metabolites that play a protective role against herbivory. Tannins can reduce palatability and bind with proteins to reduce digestibility, acting as deterrents to feeding and impacting nutrient extraction by herbivores. Some assays measure tannin and total phenolics content in plants but lack determination of their biological effects, hindering the interpretation of tannin function in herbivory and its impacts on animal behavior and ecology. In this study, we successfully applied the radial diffusion assay to assess tannin protein precipitation (PP) capacity and evaluate the anti-nutritional effects of tannins in food plants (n = 24) consumed by free-ranging black howler monkeys (Alouatta pigra) in Tabasco, Mexico. We found PP rings in five plant species consumed by the monkeys. The mature fruit of Inga edulis was the most consumed food plant, despite having a high tannin PP capacity (56.66 mg tannic acid equivalent/g dry matter). These findings highlight the presence of tannins in the black howler diet and provide insight into the primates' resilience and potential strategies for coping with anti-nutritional aspects of the diet.

Perceptions of Animal Welfare on Livestock: Evidence from College Agronomy Students in Costa Rica.

Ethical considerations regarding our treatment of animals have gained strength, leading to legislation and a societal focus across various disciplines. This is a subject of study within curricula related to agri-food sciences. The aim was to determine the perceptions of agronomy university students concerning animal welfare in livestock production systems. A survey was conducted to encompass various aspects, from participants' sociodemographic attributes to their attitudes and behaviors regarding animal welfare and the consumption of animal products. Statistical analysis, performed using R software, delved into the associations between participants' characteristics and their perspectives on the ethical, bioethical, and legal dimensions of animal welfare. Associations between demographic factors and ethical viewpoints among students were identified. Gender differences emerged in animal treatment perceptions, while rural and urban environments impacted perspectives on various animals. Bioethical considerations revealed distinctive disparities based on gender and education in concerns regarding animal welfare, value perceptions, evaluations of animal behaviors, and opinions on animal research. It is crucial to distinguish between animal welfare and the ethical considerations arising from coexisting with sentient beings capable of experiencing suffering. Ethical theories provide a lens through which we perceive our obligations toward animals. The responsibility to ensure animal welfare is firmly rooted in recognizing that animals, like humans, experience pain and physical suffering. Consequently, actions causing unjustified suffering or mistreatment, particularly for entertainment purposes, are considered morally unacceptable.

Development of a protocol for using geo-trackers to identify zoonotic enteric pathogen transmission pathways in a pilot study in Kenya

Abstract Humans and animals can be exposed to fecally-transmitted pathogens in both private and public domain environments. Animals may also acquire pathogen infections from these two environments and transmit them to humans through different pathways. Evidence on how often and where interactions occur between the two environments could improve the effectiveness of public health programs for preventing zoonotic disease transmission and response to disease outbreaks. This study aimed to develop a protocol for using geo-trackers to measure the spatial-temporal movement and interaction between animals and children in households and public areas in low- and middle-income categories of urban neighbourhoods in Kenya. It also aimed to identify opportunities and challenges for the scale-up of these methods’ for surveillance of other zoonotic diseases of public health significance. One commercial geo-tracker device with the best technological performance and usability that met pre-defined criteria for the study context was identified. Community engagement meetings were then conducted to gather input on a proposed study protocol. Afterwards, infants and animals were geo-tracked in 10 households in urban informal settlements of Kibera and Jericho, Nairobi over two consecutive weeks with iterative improvements to protocols. The effectiveness of the geo-tracking exercise was evaluated through in-depth interviews with Community Health Volunteers (CHVs) and infant caregivers. Animal and infant behaviour and battery reliability of the geo-trackers were also monitored; and observed opportunities and challenges in implementing the protocol during the exercise were documented. Community members were receptive and accepted the use of geo-trackers on animals and children. In pilot testing, there was no change of behaviour from 10 infants tracked. Discomfort was observed for up to 30 min after the placement for some of the seven animals tracked, but the animals quickly adjusted. The battery for all geo-tracker devices lasted for the 24-h geo-tracking period. Some caregivers and CHVs were concerned whether the geo-trackers could record personal information. It was shown that geo-tracker devices can be successfully deployed to study animal-child interactions and movement in different categories of urban neighbourhoods. Recommendations have been made on the lessons learnt from the study to help scientists who would use geo-trackers for future community-based human and animal research. One Health impact statement Assessing human and animal risks of acquiring enteric infections from environmental contamination, or contributing to pathogen contamination of the environment requires understanding spatial-temporal patterns of human and animal movement between private households and the community. Movement of domestic animals is relevant for understanding household-community spatial patterns of pathogen transmission because animal ownership and contact with humans is common, and free-roaming animals carrying enteric pathogens can spread diverse faecal pathogens between environments. The community-based participatory research approach of this study evaluated implementation feasibility from the lens of technical usability and reliability of geo-tracking devices, as well as social acceptability and ethics related to using such devices for the community-based study of human and animal subjects in urban settings. Evidence and recommendations from this study will be useful to anyone interested in understanding human-animal-environment interactions and their contributions to infectious disease transmission.

A new view of territoriality in large eagles: the territory pre‐exists regardless of their occupants

AbstractKnowledge of vertebrate territoriality and spatial use is a topic of great interest in the study of animal behaviour and conservation biology. Investigating the plasticity of territory boundaries, the shape of territories and how territories can be modified depending on their owners is important to deepen our knowledge of the behaviour of territorial species. We analysed the variation and tested the similarity of the distribution area of individuals from the same territory between 2015 and 2021, using data from 51 Bonelli's eagles (Aquila fasciata) from 22 different territories, tagged with GPS/GSM transmitters in eastern Spain. We calculated the percentage of overlap between the territories of the same individual in different years using the 95% kernel density estimator. We also analysed the changes in territory size and shape following the replacement of territory owners either by a single individual or by the whole pair. Our results show that territories retain the same shape and extent regardless of the occupying members, and that their boundaries change little over time. Identifying and maintaining large eagle territories, regardless of their owners, is therefore key to ensuring the long‐term recovery of these threatened species.

Inulin alleviates acute alcoholism in mice by enhancing ethanol metabolism and regulating the intestinal flora

AbstractInulin, a recognized prebiotic with diverse biological activities, has not yet been reported for its potential in treating alcoholism. Therefore, this study investigated the antialcoholic effects of short, long, and phosphorylated long‐chain inulin and the possible mechanisms. An acute alcoholic intoxication mice model was established, with the water extract of Hovenia dulcis Thunb serving as a positive control. The different inulins were used for intervention, and the drunkenness of the mice was observed by an animal behavior experiment. The serum liver function indexes (TP, ALB, GLB, ALT, and ALP), as well as the activity of ethanol metabolizing enzymes (ADH and ALDH) in the liver were measured, and the changes in intestinal flora were analyzed. The results showed that short‐chain inulin could alleviate acute alcoholism by activating ethanol metabolizing enzyme activity and improving intestinal flora, and it had a potential protective effect on acute alcoholic liver injury in mice.

3 The impact of early-life cecal microbiota transplantation on injurious behaviors in egg-laying chickens

Abstract Injurious behaviors in laying hens are a critical issue facing the poultry egg industry. Recent studies have shown that the gut microbiota influences host brain function and behavioral characteristics in humans and various animals. In laying hens, it has been reported that injurious behaviors (such as aggression, feather pecking and cannibalism) are associated with dysregulation of the microbiota-gut-brain axis. To further interrogate the role of the microbiota-gut-brain axis on bird behavior, we used two inbred layer chicken lines, 63 and 72 (line 72 displays more aggressive behavior), and transferred pooled cecal contents from either line to day of hatch chicks. Cecal microbiota transplantation (CMT) from each line was conducted once daily, by gavage, from d 1 to 10, then boosted once weekly from wk 3 to 5. We hypothesized that the cecal microbiota composition and animal behavior in recipient birds would be similar to that of their donor animals because of the microbiota-gut-brain axis. Microbial communities were compared using 16S rRNA gene amplicon sequencing, behavior was recorded in home cages as well as in paired aggression tests, and physiological measurements were taken from brain tissue and blood to measure levels of neurotransmitters and immune function. When examining the differences in the donor birds, hypothalamic serotonin and tryptophan concentrations were greater for line 63 compared with line 72 birds (P &amp;lt; 0.05). Plasma corticosterone, heterophil/lymphocyte ratios, and central norepinephrine concentrations were less for line 63 birds (P &amp;lt; 0.05). Cecal microbial diversity was not statistically different between the lines, but many bacterial taxa were differentially abundant between the two lines. After cecal transplantation, 63-CMT (recipient) birds displayed less aggressive behavior with a greater hypothalamic serotonergic activity at wk 5, similar to donor birds. Correspondingly, two amplicon sequence variants (ASVs) belonging to Lachnospiraceae and one Ruminococcaceae UCG-005 ASV were positively correlated with the concentrations of brain tryptophan and serotonin, respectively. Along with greater aggression, 72-CMT birds seemed to have greater physical growth traits (increased body weight, ileal villus/crypt; P ≤ 0.05), but decreased concentrations of brain norepinephrine and dopamine, and the greatest ileal serotonin turnover in the ileum at wk 5 (P &amp;lt; 0.05). ASVs belonging to Mollicutes RF39 and GCA-900066225 in 72-CMT birds were negatively correlated with the brain 5-hydroxyindoleacetic acid (5-HIAA) at wk 5, and one Bacteroides ASV was negatively correlated with plasma serotonin at wk 16. Meanwhile, 63-CMT birds potentially had better gut health and immune function (greater concentrations of ileal mucosal secretory IgA, plasma IL-10; P &amp;lt; 0.05). These results suggest linkages among serotonergic activity, stress response, innate immunity, and gut microbiota populations and that CMT could be a novel strategy for reducing aggressive behavior through regulating signaling along the microbiota-gut-brain axis.

106 Net energy of soybean meal

Abstract Our current net energy (NE) systems were developed based on work conducted around 40 yr ago. At that time, it was normal that pigs deposited no more than 40% of the protein they were fed. However, modern genetic lines are much leaner than older genetics and they deposit more protein than earlier. It is, therefore, not uncommon that protein deposition in modern genotypes exceeds 60% of dietary protein intake. This means that more of the amino acids in the protein-rich ingredients are used for protein deposition and less are being deaminated with a subsequent reduced energetic cost of deamination associated with feeding protein-rich ingredients. As a consequence, the theoretical energy value of protein rich ingredients such as soybean meal (SBM) is greater when fed to modern pigs than to older genotypes that were used when our current NE systems were developed. Indeed, in several recent experiments it was demonstrated that the ME and NE of SBM is greater than indicated in current feed ingredient tables. A greater NE than predicted has also been demonstrated for field peas, whereas corn does not seem to have increased energy value compared with previous estimates, which is consistent with the hypothesis that it is the increased protein efficiency of modern pigs that is the reason for the greater NE value in SBM. As a consequence of the greater NE value of SBM, less added fat need to be used to reach a certain NE level in the diet, which will reduce overall diet costs. However, because of the greater genetic capacity for protein deposition in modern pigs, there is a need to upgrade the NE system and to develop new equations to predict NE in diets and ingredients based on the protein deposition capacity of modern pigs. It can also be argued that because commercially fed pigs always are group housed and allowed ad libitum intake of feed, pigs fed to generate prediction equations for NE also need to be group housed and allowed ad libitum intake of feed because both animal behavior and level of feed intake may affect the NE value of diets. In conclusion, because of the increased ability of modern genotypes of pigs to retain dietary protein in the body, there is reduced deamination of amino acids and therefore reduced energy loss in modern pigs than in older genotypes, which results in greater NE of protein rich ingredients including SBM. There is, therefore, a need for developing a new NE system that preferably uses group-housed pigs that are allowed ad libitum access to feed.

Effects of systemic inflammation on the network oscillation in the anterior cingulate cortex and cognitive behavior.

Network oscillation in the anterior cingulate cortex (ACC) plays a key role in attention, novelty detection and anxiety; however, its involvement in cognitive impairment caused by acute systemic inflammation is unclear. To investigate the acute effects of systemic inflammation on ACC network oscillation and cognitive function, we analyzed cytokine level and cognitive performance as well as network oscillation in the mouse ACC Cg1 region, within 4 hours after lipopolysaccharide (LPS, 30 μg/kg) administration. While the interleukin-6 concentration in the serum was evidently higher in LPS-treated mice, the increases in the cerebral cortex interleukin-6 did not reach statistical significance. The power of kainic acid (KA)-induced network oscillation in the ACC Cg1 region slice preparation increased in LPS-treated mice. Notably, histamine, which was added in vitro, increased the oscillation power in the brain slices from LPS-untreated mice; for the LPS-treated mice, however, the effect of histamine was suppressive. In the open field test, frequency of entries into the center area showed a negative correlation with the power of network oscillation (0.3 μM of KA, theta band (3-8 Hz); 3.0 μM of KA, high-gamma band (50-80 Hz)). These results suggest that LPS-induced systemic inflammation results in increased network oscillation and a drastic change in histamine sensitivity in the ACC, accompanied by the robust production of systemic pro-inflammatory cytokines in the periphery, and that these alterations in the network oscillation and animal behavior as an acute phase reaction relate with each other. We suggest that our experimental setting has a distinct advantage in obtaining mechanistic insights into inflammatory cognitive impairment through comprehensive analyses of hormonal molecules and neuronal functions.

Dogs understand the role of a human partner in a cooperative task

Humans are exceptionally flexible in cooperation, partly due to our ability to recognize the roles of cooperative partners. While some non-human animals understand the need for a partner in such interactions, it is unclear whether they grasp the consequences of their partner’s actions and adjust accordingly. Previous studies utilizing economic games with non-human animals yielded mixed results. We investigated dogs, known for their close cooperation with humans, in a stag hunt game. Dogs could cooperate for better rewards or defect for lower ones, while their human partners would either cooperate, never cooperate, or act randomly. We control for attraction to food, side bias, and local enhancement. Dogs were more likely to coordinate with their partners when it led to better rewards, suggesting that they understood their partner’s actions. By highlighting this cognitive skill in dogs, we advance our knowledge of the intricate mechanisms driving cooperative behavior in non-human animals.

Parasite infestation patterns differ between ticks and chigger mites on two rodent host species in Taiwan.

Parasites are typically concentrated on a few host individuals, and identifying the mechanisms underlying aggregated distribution can facilitate a more targeted control of parasites. We investigated the infestation patterns of hard ticks and chigger mites on two rodent species, the striped field mouse, Apodemus agrarius, and the lesser ricefield rat, Rattus losea, in Taiwan. We also explored abiotic and biotic factors that were important in explaining variation in the abundance of ticks and chiggers on rodent hosts. Ticks were more aggregated than chiggers on both rodent species. Factors important for the variation in parasitic loads, especially biotic factors, largely differed between ticks and chiggers. Variation partitioning analyses revealed that a larger proportion of variation in chiggers than in ticks can be explained, especially by abiotic factors. If, as proposed, the higher number of parasites in males is due to a larger range area or immunity being suppressed by testosterone, when A. agrarius males host more ticks, they are expected to also host more chiggers, given that chiggers adopt a similar host finding approach to that of ticks. Instead, the similar abundance of chiggers in male and female A. agrarius implies that a large home range or suppressed immunity does not predispose males to inevitably host more parasites. More variations were explained by abiotic than biotic factors, suggesting that controlling practices are more likely to be successful by focusing on factors related to the environment instead of host traits. Our study indicated that the extent of parasitism is rarely determined by a sole factor, but is an outcome of complex interactions among animal physiology, animal behavior, characteristics of parasites, and the environments.

A novel animal model for understanding secondary traumatic stress and visceral pain in male rats.

Empathetic relationships and the social transference of behaviours have been shown to occur in humans, and more recently through the development of rodent models, where both fear and pain phenotypes develop in observer animals. Clinically, observing traumatic events can induce 'trauma and stressor-related disorders' as defined in the DSM 5. These disorders are often comorbid with pain and gastrointestinal disturbances; however, our understanding of how gastrointestinal - or visceral - pain can be vicariously transmitted is lacking. Visceral pain originates from the internal organs, and despite its widespread prevalence, remains poorly understood. We established an observation paradigm to assess the impact of witnessing visceral pain. We utilised colorectal distension (CRD) to induce visceral pain behaviours in a stimulus rodent while the observer rodent observed. Twenty four hours post-observation, the observer rodent's visceral sensitivity was assessed using CRD. The observer rodents were found to have significant hyperalgesia as determined by lower visceral pain threshold and higher number of total pain behaviours compared with controls. The behaviours of the observer animals during the observation were found to be correlated with the behaviours of the stimulus animal employed. We found that observer animals had hypoactivity of the hypothalamic-pituitary-adrenal (HPA) axis, highlighted by reduced corticosterone at 90 minutes post-CRD. Using c-Fos immunohistochemistry we showed that observer animals also had increased activation of the anterior cingulate cortex, and decreased activation of the paraventricular nucleus, compared with controls. These results suggest that witnessing another animal in pain produces a behavioural phenotype and impacts the brain-gut axis.

A Point Cloud Segmentation Method for Pigs from Complex Point Cloud Environments Based on the Improved PointNet++

In animal husbandry applications, segmenting live pigs in complex farming environments faces many challenges, such as when pigs lick railings and defecate within the acquisition environment. The pig’s behavior makes point cloud segmentation more complex because dynamic animal behaviors and environmental changes must be considered. This further requires point cloud segmentation algorithms to improve the feature capture capability. In order to tackle the challenges associated with accurately segmenting point cloud data collected in complex real-world scenarios, such as pig occlusion and posture changes, this study utilizes PointNet++. The SoftPool pooling method is employed to implement a PointNet++ model that can achieve accurate point cloud segmentation for live pigs in complex environments. Firstly, the PointNet++ model is modified to make it more suitable for pigs by adjusting its parameters related to feature extraction and sensory fields. Then, the model’s ability to capture the details of point cloud features is further improved by using SoftPool as the point cloud feature pooling method. Finally, registration, filtering, and extraction are used to preprocess the point clouds before integrating them into a dataset for manual annotation. The improved PointNet++ model’s segmentation ability was validated and redefined with the pig point cloud dataset. Through experiments, it was shown that the improved model has better learning ability across 529 pig point cloud data sets. The optimal mean Intersection over Union (mIoU) was recorded at 96.52% and the accuracy at 98.33%. This study has achieved the automatic segmentation of highly overlapping pigs and pen point clouds. This advancement enables future animal husbandry applications, such as estimating body weight and size based on 3D point clouds.

Rethinking core affect: the role of dominance in animal behaviour and welfare research

This paper critically examines the philosophical underpinnings of current experimental investigation into animal affect-related decision-making. Animals’ affective states are standardly operationalised by linking positively valenced states with “approach” behaviours and negatively valenced states with “avoidance” behaviours. While this operationalisation has provided a helpful starting point to investigate the ecological role of animals’ internal states, there is extensive evidence that valenced and motivational states do not always neatly align, namely, instances where “liking” does not entail “wanting” (and vice versa). To address this limitation, this paper proposes the (re-)integration of dominance as a dimension of affect. In particular, I argue that dominance, construed as a measure of organisms’ self-assessed behavioural control, can provide the necessary nuance to understand animal affect-related decision-making. Thus, after addressing the theoretical and methodological challenges related to incorporating dominance into a definition of “core affect”, this paper introduces the “Valence-Arousal-Dominance” model of animal affect. This model is explored for its potential applications in two domains. Firstly, in the study of animal affect-related decision-making under predation risk, and secondly, in the study of animal wellbeing. Through these applications, this model aims to bring experimental paradigms of animal affect-related behaviour closer to ecologically relevant scenarios.

Identifying animal behaviours from accelerometers: Improving predictive accuracy of machine learning by refining the variables selected, data frequency, and sample duration.

Observing animals in the wild often poses extreme challenges, but animal-borne accelerometers are increasingly revealing unobservable behaviours. Automated machine learning streamlines behaviour identification from the substantial datasets generated during multi-animal, long-term studies; however, the accuracy of such models depends on the qualities of the training data. We examined how data processing influenced the predictive accuracy of random forest (RF) models, leveraging the easily observed domestic cat (Felis catus) as a model organism for terrestrial mammalian behaviours. Nine indoor domestic cats were equipped with collar-mounted tri-axial accelerometers, and behaviours were recorded alongside video footage. From this calibrated data, eight datasets were derived with (i) additional descriptive variables, (ii) altered frequencies of acceleration data (40 Hz vs. a mean over 1 s) and (iii) standardised durations of different behaviours. These training datasets were used to generate RF models that were validated against calibrated cat behaviours before identifying the behaviours of five free-ranging tag-equipped cats. These predictions were compared to those identified manually to validate the accuracy of the RF models for free-ranging animal behaviours. RF models accurately predicted the behaviours of indoor domestic cats (F-measure up to 0.96) with discernible improvements observed with post-data-collection processing. Additional variables, standardised durations of behaviours and higher recording frequencies improved model accuracy. However, prediction accuracy varied with different behaviours, where high-frequency models excelled in identifying fast-paced behaviours (e.g. locomotion), whereas lower-frequency models (1 Hz) more accurately identified slower, aperiodic behaviours such as grooming and feeding, particularly when examining free-ranging cat behaviours. While RF modelling offered a robust means of behaviour identification from accelerometer data, field validations were important to validate model accuracy for free-ranging individuals. Future studies may benefit from employing similar data processing methods that enhance RF behaviour identification accuracy, with extensive advantages for investigations into ecology, welfare and management of wild animals.

Bringing Artificial Intelligence (AI) into Environmental Toxicology Studies: A Perspective of AI-Enabled Zebrafish High-Throughput Screening.

The booming development of artificial intelligence (AI) has brought excitement to many research fields that could benefit from its big data analysis capability for causative relationship establishment and knowledge generation. In toxicology studies using zebrafish, the microscopic images and videos that illustrate the developmental stages, phenotypic morphologies, and animal behaviors possess great potential to facilitate rapid hazard assessment and dissection of the toxicity mechanism of environmental pollutants. However, the traditional manual observation approach is both labor-intensive and time-consuming. In this Perspective, we aim to summarize the current AI-enabled image and video analysis tools to realize the full potential of AI. For image analysis, AI-based tools allow fast and objective determination of morphological features and extraction of quantitative information from images of various sorts. The advantages of providing accurate and reproducible results while avoiding human intervention play a critical role in speeding up the screening process. For video analysis, AI-based tools enable the tracking of dynamic changes in both microscopic cellular events and macroscopic animal behaviors. The subtle changes revealed by video analysis could serve as sensitive indicators of adverse outcomes. With AI-based toxicity analysis in its infancy, exciting developments and applications are expected to appear in the years to come.

Animal behavior: A tale of two apes

Animal behavior: A tale of two apes

Ontogenetic transition from aquatic to amphibious life in the mudskipper, Periophthalmus modestus

Vertebrates first emerged from water to land in the Paleozoic. Our understanding about the process has been steadily refined through paleontological studies, although the soft-body traits and behavior of these early animals remain poorly known. Mudskippers, extant amphibious gobies, could give insight into this question. This study reports on the ontogenetic transition from water to land of the mudskipper Periophthalmus modestus under laboratory conditions. After about 30 days after hatching (dah), the fish gradually changed their preference from water to an artificial shore and then to land. After about five days of periodic volitional emersion, the fish became able to propel themselves on land using the pectoral fins and after a further 13 days they began feeding on land. During the transition, the head morphology altered to suit for terrestrial existence. Tissue contents of triiodothyronine (T3) and thyroxine (T4) sharply increased at 30 dah. Forced underwater confinement of larvae at the last pelagic stage (27–29 dah) for 40–42 days resulted in no statistically significant difference in survival or gross morphology of the body and the gills. Growth was slightly stimulated. Our results show that mudskippers emerge on land with little morphological alteration during ontogenesis, much less than the changes observed for amphibians, and that emersion was not indispensable for survival or growth under our laboratory conditions. Further analysis of how and why mudskippers make their way across the water’s edge will shed valuable light on what morphological, behavioral and physiological traits were needed for, and what environmental conditions may have driven the earliest steps of the water-to-land transition in ancient fishes.