A Computerized Simulation of the Occlusal Surface in Equine Cheek Teeth: A Simplified Model

Equine mastication, as well as dental wear patterns, is highly important for the development of treatments in equine dentistry. During the last decades, the stress and strain distributions of equine teeth have been successfully simulated using finite element analysis. Yet, to date, there is no simulation available for dental tooth wear in equines. In this study, we developed a simplified two-dimensional computer simulation of dental wear. It provides a first tentative explanation for the development of the marked physiological inclination of the occlusal surface and for pathological conditions such as sharp enamel points in equine cheek teeth. The mechanical properties of the dental structures as well as the movement of the mandible during the equine chewing cycle were simulated according to previously published data. The simulation setup was optimized in preliminary test runs. Further simulations were conducted varying the lateral excursion of the mandible and the presence or absence of incisor contact during the chewing cycle. The results of simulations showed clear analogies to tooth wear patterns in living equids, including the formation of wear abnormalities. Our analysis indicates that small variations in the pattern of movement during the masticatory cycle, as well as incisor contacts, are leading to marked changes in the occlusal tooth wear patterns. This opens new research avenues to better understand the development of dental wear abnormalities in equines and might have serious implications on captive animal health, welfare, and longevity.

Possibilities and limits for using the gut microbiome to improve captive animal health

Because of its potential to modulate host health, the gut microbiome of captive animals has become an increasingly important area of research. In this paper, we review the current literature comparing the gut microbiomes of wild and captive animals, as well as experiments tracking the microbiome when animals are moved between wild and captive environments. As a whole, these studies report highly idiosyncratic results with significant differences in the effect of captivity on the gut microbiome between host species. While a few studies have analyzed the functional capacity of captive microbiomes, there has been little research directly addressing the health consequences of captive microbiomes. Therefore, the current body of literature cannot broadly answer what costs, if any, arise from having a captive microbiome in captivity. Addressing this outstanding question will be critical to determining whether it is worth pursuing microbial manipulations as a conservation tool. To stimulate the next wave of research which can tie the captive microbiome to functional and health impacts, we outline a wide range of tools that can be used to manipulate the microbiome in captivity and suggest a variety of methods for measuring the impact of such manipulation preceding therapeutic use. Altogether, we caution researchers against generalizing results between host species given the variability in gut community responses to captivity and highlight the need to understand what role the gut microbiome plays in captive animal health before putting microbiome manipulations broadly into practice.

Cognitive Enrichment in Practice: A Survey of Factors Affecting Its Implementation in Zoos Globally

Information on the practical use of cognitive enrichment in zoos is scarce. This survey aimed to identify where cognitive enrichment is being used while identifying factors that may limit its implementation and success. Distributed in eight languages to increase global range, responses to this survey (n = 177) show that while agreement on what constitutes cognitive enrichment is poor, it is universally perceived as very important for animal welfare. Carnivores were the animal group most reported to receive cognitive enrichment (76.3%), while amphibians and fish the least (16.9%). All animal groups had a percentage of participants indicating animal groups in their facility were not receiving cognitive enrichment when they believe that they should (29.4–44.6%). On average, factors relating to time and finance were rated most highly in terms of effect on cognitive enrichment use, and keeper interest was the highest rated for effect on success. Results of this study indicate that cognitive enrichment is perceived as important. However, placing the responsibility of its development and implementation on animal keepers who are already time-poor may be impeding its use. A commitment to incorporating cognitive enrichment into routine husbandry, including financial support and investment into staff is needed from zoos to ensure continued improvement to captive animal welfare.

Leveraging Social Learning to Enhance Captive Animal Care and Welfare

From ants to zebras, animals are influenced by the behavior of others. At the simplest level, social support can reduce neophobia, increasing animals’ exploration of novel spaces, foods, and other environmental stimuli. Animals can also learn new skills more quickly and more readily after observing others perform them. How then can we apply animals’ proclivity to socially learn to enhance their care and welfare in captive settings? Here, I review the ways in which animals (selectively) use social information, and propose tactics for leveraging that to refine the behavioral management of captive animals: to enhance socialization techniques, enrichment strategies, and training outcomes. It is also important to consider, however, that social learning does not always promote the uniform expression of new behaviors. There are differences in animals’ likelihood to seek out or use socially provided information, driven by characteristics such as species, rank, age, and personality. Additionally, social learning can result in inexact transmission or the transmission of undesirable behaviors. Thus, understanding when, how, and why animals use social information is key to developing effective strategies to improve how we care for animals across settings and, ultimately, enhance captive animal welfare.

Extinction of the Thylacine

The Thylacine (Thylacinus cynocephalus), or ‘Tasmanian tiger’, is an icon of recent extinctions, but the timing of its final demise is shrouded in controversy. Extirpated from mainland Australia in the mid-Holocene, the large island of Tasmania became the species’ final stronghold. Following European settlement, the Thylacine was heavily persecuted and pushed to the margins of its range. The last captive animal died in 1936, but numerous sightings were reported thereafter. Here we collate and characterize the type, quality, and uncertainty of over a thousand unique sighting records of Thylacines since 1910. We use this novel and unique curated database to underpin a detailed reconstruction and mapping of the species’ spatio-temporal distributional dynamics, to pinpoint refugia of late survival and estimate the bioregional patterns of extirpation. Contrary to expectations, the inferred extinction window is wide and relatively recent, spanning from the 1980s to the present day, with extinction most likely in the late 1990s or early 2000s. While improbable, these aggregate data and modelling suggest some chance of ongoing persistence in the remote wilderness of the island. Although our findings for this iconic species hold intrinsic value, our new spatio-temporal mapping of extirpation patterns is also applicable more generally, to support the conservation prioritization and search efforts for other rare taxa of uncertain status.Significance statementLike the Dodo and Passenger Pigeon before it, the Thylacine has become an iconic symbol of human-caused extinction. Even today, reports of the Thylacine’s possible ongoing survival in remote regions of Tasmania are newsworthy and continue to capture the public’s imagination, with much debate over whether the extinction event has yet occurred and if so, when? We show, using a unique and robust spatio-temporal mapping and modelling approach, underpinned by the world’s first sightings database (from 1910-present day), that the Thylacine likely persisted until the late 20th century, with some possibility of ongoing survival.

A Preliminary Study Investigating the Impact of Musical Concerts on the Behavior of Captive Fiordland Penguins (Eudyptes pachyrhynchus) and Collared Peccaries (Pecari tajacu)

Captive animal welfare is important for establishments that exhibit species for education, conservation, and research. However, captive animals are often exposed to a number of potential stressors, such as visitors and anthropogenic noise. We aimed to identify the impact of a concert series on the behaviour of Fiordland penguins (Eudyptes pachyrhynchus; n = 2), and solitary- (n = 1) or group- (n = 4)-housed collared peccaries (Pecari tajacu). Animal behaviour, visitor density, and visitor behaviour was monitored pre-concert (afternoons; 16:00–19:00), during the concert (evenings; 19:00–21:00), and post-concert (nights; 21:00–00:00) on concert days (penguin n = 7 days; peccary n = 8 days) and in the same periods on days when there was no concert (penguin n = 8 days; peccary n = 6 days). Fiordland penguins spent more time surface swimming and diving in the pool on concert afternoons and evenings (all p < 0.001), more time in the nest on concert nights (p < 0.001), preened less on concert afternoons and nights (p = 0.019), and engaged with their habitat less on concert evenings and nights (p = 0.002) compared to these periods on days without a concert. The group-housed peccaries slept more in the afternoon and evening (p ≤ 0.01) and were more vigilant at night (p = 0.009) on concert days compared to no-concert days. The solitary-housed peccary slept more on concert nights (p = 0.035), rested more frequently across all time periods on concert days (p < 0.001), and used the front of the enclosure more across all concert time periods (p < 0.001) compared to no-concert days. We provide evidence that behaviour was altered on event days; however, we cannot determine the nature of these changes. Further research is needed to understand the impact of music concerts on zoo animal welfare.

Dilemmas for Natural Living Concepts of Zoo Animal Welfare

This ethical discourse specifically deals with dilemmas encountered within zoological institutions, namely for the concept of natural living, and a new term—wilding. It is agreed by some that zoos are not ethically wrong in principle, but there are currently some contradictions and ethical concerns for zoos in practice. Natural living is a complicated concept, facing multiple criticisms. Not all natural behaviours, nor natural environments, are to the benefit of animals in a captive setting, and practical application of the natural living concept has flaws. Expression of natural behaviours does not necessarily indicate positive well-being of an animal. Herein it is suggested that highly-motivated behaviours may be a better term to properly explain behaviours of more significance to captive animals. Wilding refers to extrapolation of the natural living concept to treating an animal as wild, residing in a wild habitat. This definition is intrinsically problematic, as quite literally by definition, captivity is not a wild nor natural environment. Treating a captive animal exactly the same as a wild counterpart is practically impossible for many species in a few ways. This article discusses complexities of natural living versus natural aesthetics as judged by humans, as well as the possibility of innate preference for naturalness within animals. Zoos nobly strive to keep wild animals as natural and undomesticated as possible. Here it is argued that unintended and unavoidable genetic and epigenetic drift favouring adaptations for life in a captive environment may still occur, despite our best efforts to prevent this from occurring. This article further discusses the blurred lines between natural and unnatural behaviours, and the overlaps with more important highly-motivated behaviours, which may be better predictors of positive affective states in captive animals, and thus, better predictors of positive well-being and welfare. Finally, as we are now in the Anthropocene era, it is suggested that human-animal interactions could actually be considered natural in a way, and notwithstanding, be very important to animals that initiate these interactions, especially for “a life worth living”.

Captive jays exhibit reduced problem-solving performance compared to wild conspecifics

Animal cognitive abilities are frequently quantified in strictly controlled settings, with laboratory-reared subjects. Results from these studies have merit for clarifying proximate mechanisms of performance and the potential upper limits of certain cognitive abilities. Researchers often assume that performance on laboratory-based assessments accurately represents the abilities of wild conspecifics, but this is infrequently tested. In this experiment, we quantified the performance of wild and captive corvid subjects on an extractive foraging task. We found that performance was not equivalent, and wild subjects were faster at problem-solving to extract the food reward. By contrast, there was no difference in the time it took for captive and wild solvers to repeat the behaviour to get additional food rewards (learning speed). Our findings differ from the few other studies that have statistically compared wild and captive performance on assessments of problem-solving and learning. This indicates that without explicitly testing it, we cannot assume that captive animal performance on experimental tasks can be generalized to the species as a whole. To better understand the causes and consequences of a variety of animal cognitive abilities, we should measure performance in the social and physical environment in which the ability in question evolved.