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The use of electronic tags has significantly advanced our understanding of wild animal behaviour and physiology. However, traditional tagging methods often require capturing and restraining or sedating animals, which causes stress and may potentially affect data quality during acclimatization. Inspired by plant burs, we propose a novel ‘bur-tagging’ system to attach tags without capture or restraint. We outline a framework for bur-tagging, detailing the design and key considerations for its success. This includes the influence of tagging site location and animal neophobia on the likelihood of tagging over time, strategies to target specific species, and methods to improve tag placement accuracy. The choice of adhesive mechanism and application force are discussed as critical factors for effective attachment. Preliminary trials highlight animal reactions to inactive tagging systems, demonstrating ways to minimize stress and increase tagging efficiency. Field tests on domestic animals and wild canids in Greece suggest that bur-tagging is a viable alternative to conventional methods. While still in development, bur-tagging has the potential to deploy advanced electronic tags on wild animals with reduced stress and greater ethical consideration, offering a promising tool for wildlife research. This innovative approach bridges biology and technology to address challenges in animal tagging.

Bio-logging is a common method to collect ecological data on wild animals, but might also induce stress, reduce body condition, and alter behavior. Eurasian beavers (Castor fiber) are a semi-aquatic and nocturnal species that are challenging to observe in the wild. Bio-loggers are hence useful tools to study their behaviour and movements, but this raises concerns of potential negative impacts of tagging. To investigate the potential negative impacts of glue-on tags, we compared body weight change for tagged and untagged Eurasian beavers. We hypothesized that tagged beavers would gain less body weight compared to untagged beavers, and that weight change might be affected by tagging length, tag weight, water temperature and the season of tagging. Daily percentage body weight change in relation to initial body weight during the first capture was compared during 57 tagging periods (18±7 days) and 32 controls periods (64±47 days). Body weight change varied between the two groups, with untagged beavers on average gaining daily weight whilst tagged beavers on average lost weight daily, indicating a negative effect of tagging. The average reduction in percentage body weight change per day for tagged beavers was small (0.1 ± 0.3%), and with large individual variation. Neither tag weight, number of tagging days, nor season were important in explaining body weight change of tagged animals. In other words, we found that tagging reduced daily body weight during the tagging period but were unable to determine the mechanism(s) responsible for this decline. Detrimental effects of tagging have important implications for animal welfare and can introduce bias in data that are collected. This calls for careful consideration in the use of tags. We conclude that studies investigating the effects of tagging should consider individual variation in the effects of tagging and, where possible, compare tagged animals with a control group.

With increasing technology and knowledge, the range of methods used to monitor wildlife is growing. As many invasive techniques have been shown to negatively impact study populations, the use of non-invasive methods is increasing. With Eurasian beaver (Castor fiber) reintroductions occurring across much of Europe, monitoring of beavers is becoming increasingly important; however, some frequently used techniques are invasive. We therefore aimed to examine potentially non-invasive methods of identifying and ageing them from the tail. Tails from previously deceased beavers were photographed with a Nikon D3500 DSLR camera across 3 distances: ‘close’, ‘medium’ and ‘far’, and the pattern of the scales were examined by eye to determine accuracy of individual identification. Photographs including a grey standard were used to determine the accuracy of ageing beavers from the colour of the tail. The accuracy of individual identification was 100% across all distances; however, the results from ageing showed the method to be inaccurate. The success of the individual identification shows that this method could be effectively used as a non-invasive method for monitoring beaver populations, especially in captivity.

Animals balance foraging with other activities, and activity patterns may differ between sexes due to differing physical requirements and reproductive investments. Sex-specific behavioural differences are common in sexually dimorphic mammals, but have received limited research attention in monomorphic mammals where the sexes are similar in body size. Eurasian beavers (Castor fiber) are obligate monogamous and monomorphic mammals and a good model species to study sex-specific differences. As females increase energy expenditure during reproduction, we hypothesized differing seasonal activity budgets, circadian activity rhythms and foraging patterns between male and reproducing female beavers. To test this hypothesis, we equipped adult beavers with VHF transmitters (N=41; 16 female, 25 male) and observed them throughout their active period at night from spring to late summer. Occurrence of their main activities (foraging, travelling and being in lodge) and use of food items (trees/shrubs, aquatic vegetation and herbs/grasses) were modelled to investigate sex-specific seasonal activity budgets and circadian activity rhythms. The sexes did not differ in time spent foraging across the season or night, but during spring, females resided more in the lodge and travelled less. Males and females both foraged on aquatic vegetation during spring, but females used this food source also during late summer, whereas males mostly foraged on trees/shrubs throughout the year. We conclude that seasonal activity budgets and foraging differ subtly between the sexes, which may relate to different energy budgets associated with reproduction and nutritional requirements. Such subtle seasonal behavioural adaptions may be vital for survival and reproduction of monomorphic species.

Animals balance foraging with other activities, and activity patterns may differ between sexes due to differing physical requirements and reproductive investments. Sex-specific behavioural differences are common in sexually dimorphic mammals, but have received limited research attention in monomorphic mammals where the sexes are similar in body size. Eurasian beavers (Castor fiber) are obligate monogamous and monomorphic mammals and a good model species to study sex-specific differences. As females increase energy expenditure during reproduction, we hypothesized differing seasonal activity budgets, circadian activity rhythms and foraging patterns between male and reproducing female beavers. To test this hypothesis, we equipped adult beavers with VHF transmitters (N=41; 16 female, 25 male) and observed them throughout their active period at night from spring to late summer. Occurrence of their main activities (foraging, travelling and being in lodge) and use of food items (trees/shrubs, aquatic vegetation and herbs/grasses) were modelled to investigate sex-specific seasonal activity budgets and circadian activity rhythms. The sexes did not differ in time spent foraging across the season or night, but during spring, females resided more in the lodge and travelled less. Males and females both foraged on aquatic vegetation during spring, but females used this food source also during late summer, whereas males mostly foraged on trees/shrubs throughout the year. We conclude that seasonal activity budgets and foraging differ subtly between the sexes, which may relate to different energy budgets associated with reproduction and nutritional requirements. Such subtle seasonal behavioural adaptions may be vital for survival and reproduction of monomorphic species.

Many wild animals perceive humans as predators, and human disturbance, especially in the form of hunting, triggers antipredatory behavior among prey. Yet, knowledge of how game species react to different types of human disturbance and adapt to repeated disturbances is limited. We investigated how disturbance in the form of a solitary human approacher (stalker) impacted behavior (flight response and short‐term habitat use) of 28 GPS‐collared red deer (Cervus elaphus) in two populations with contrasting population densities in Norway. We studied how the behavioral response differed: (1) with season (pre‐hunting vs. hunting); (2) by consecutive approaches within a day; (3) among replicated experiments within the same season; and (4) between two regions with contrasting densities of red deer. The average flight initiation distance (FID) increased by 15% during the hunting season, and consecutive approaches within the same day caused the red deer to move 49% longer distances. Flight initiation distance was longer in the high‐density population, while escape distance was longer in the low‐density population. Red deer moved out of their weekly home range after 52% approaches, and after the onset of hunting season, time spent outside the home range increased by 89%. Red deer preferred denser resting sites after the disturbance and animal sites had shorter sighting distance and higher canopy cover than control plots. Tree density and canopy cover at animal sites increased at the onset of hunting season, from first to second approach within day, and after replicated experiments within season. Our results suggest that red deer preferred dense resting sites, especially in the hunting season. However, these animal sites had the same amount of the favorable forage plant bilberry (Vaccinium myrtillus), indicating no clear food–cover trade‐off in selection of habitat. Our study showed that onset of hunting initiates stronger fear responses in red deer, which may in turn affect red deer distribution and harvesting efficiency.

Abstract Camera traps are commonly used to monitor and study wild animals in their natural habitat, with minimal disturbance. Several investigations have shown that the natural markings of animals for some species can be used for individual recognition. However, most commercially available cameras are unable to obtain photos of sufficient quality to highlight these features. Our study further exemplifies the use of applying an external lens to a camera, to obtain higher quality images. We tested various lenses and their ability to record the scale patterns on Eurasian beaver (Castor fiber) tails, for individual identification. We tested eleven different commercially available camera trap models, across six different beaver territories in the Districts of Kleve and Wesel (North Rhine-Westphalia, Germany). The use of an external lens, attached to the camera, produced the best quality pictures for reliable identification of individual beavers based on the scale patterns on their tales. These results further exemplify the application of external lenses for improving image quality for individual recognition which has potential applications for other species.

Individual recognition of animals is an important aspect of ecological sciences. Photograph-based individual recognition options are of particular importance since these represent a non-invasive method to distinguish and identify individual animals. Recent developments and improvements in computer-based approaches make possible a faster semi-automated evaluation of large image databases than was previously possible. We tested the Scale Invariant Feature Transform (SIFT) algorithm, which extracts distinctive invariant features of images robust to illumination, rotation or scaling of images. We applied this algorithm to a dataset of 800 tail pattern images from 100 individual Eurasian beavers (Castor fiber) collected as part of the Norwegian Beaver Project (NBP). Images were taken using a single-lens reflex camera and the pattern of scales on the tail, similar to a human fingerprint, was extracted using freely accessible image processing programs. The focus for individual recognition was not on the shape or the scarring of the tail, but purely on the individual scale pattern on the upper (dorsal) surface of the tail. The images were taken from two different heights above ground, and the largest possible area of the tail was extracted. The available data set was split in a ratio of 80% for training and 20% for testing. Overall, our study achieved an accuracy of 95.7%. We show that it is possible to distinguish individual beavers from their tail scale pattern images using the SIFT algorithm.

Climate change poses a significant threat to species with temperature-dependent sex determination, such as sea turtles. Their conservation often involves relocating nests to hatcheries, which is also crucial on the Pacific coast of Guatemala, where virtually no hatchlings emerge from natural nests. Populations there rely heavily on hatcheries, yet nest temperature monitoring in relation to environmental and management factors is rarely conducted. Research is needed to improve artificial nest management and hatchery design. This study investigated how distance to the hatchery wall, number of eggs, position in the nest, development period, season, and weather conditions influenced temperature variation in Olive Ridley Turtle (Lepidochelys olivacea) nests. We generally found nest temperatures within viable ranges and near the pivotal temperature for Olive Ridleys. The pivotal temperature of Olive Ridley was exceeded 6%–21% of the time during the thermosensitive period of all nests (starting days 9–15 and ending days 33–37 of incubation), and the upper thermal tolerance limit was rarely reached. However, nests closer to concrete walls were up to 1°C warmer than those farther away, and 30–40 more eggs per nest raised average temperatures by 0.7°C. These findings suggest that distance to hatchery walls and egg numbers per nest can be tools to manipulate nest temperatures and sex ratios. The sex ratios in this study were slightly female-biased. However, optimal sex ratios remain poorly understood, and reliance on ex situ incubation may reduce population adaptability to environmental changes. Ex situ nest conditions in our study displayed lower temperatures than potential in situ conditions, which exceeded the lethal threshold in 86% (z-test, p < 0.001) of the measurements. Our study emphasizes the need for careful hatchery management to safeguard sea turtles against the effects of climate change but also to avoid the consequences of overcompensation due to mismanagement.

Many wild animals perceive humans as predators, and human disturbance,especially in the form of hunting, triggers antipredatory behavior among prey.Yet, knowledge of how game species react to different types of human distur-bance and adapt to repeated disturbances is limited. We investigated howdisturbance in the form of a solitary human approacher (stalker) impactedbehavior (flight response and short-term habitat use) of 28 GPS-collared reddeer (Cervus elaphus) in two populations with contrasting population densitiesin Norway. We studied how the behavioral response differed: (1) with season(pre-hunting vs. hunting); (2) by consecutive approaches within a day;(3) among replicated experiments within the same season; and (4) betweentwo regions with contrasting densities of red deer. The average flight initiationdistance (FID) increased by 15% during the hunting season, and consecutiveapproaches within the same day caused the red deer to move 49% longerdistances. Flight initiation distance was longer in the high-density population,while escape distance was longer in the low-density population. Red deermoved out of their weekly home range after 52% approaches, and after theonset of hunting season, time spent outside the home range increased by 89%.Red deer preferred denser resting sites after the disturbance and animal siteshad shorter sighting distance and higher canopy cover than control plots.Tree density and canopy cover at animal sites increased at the onset of huntingseason, from first to second approach within day, and after replicated experi-ments within season. Our results suggest that red deer preferred dense restingsites, especially in the hunting season. However, these animal sites had thesame amount of the favorable forage plant bilberry (Vaccinium myrtillus), indi-cating no clear food–cover trade-off in selection of habitat. Our study showedthat onset of hunting initiates stronger fear responses in red deer, which mayin turn affect red deer distribution and harvesting efficiency