Kyoto City Zoo

Abstract Information on age is essential for exploring the life history, conservation, and management of wildlife. Recently, DNA methylation levels-based methods using blood or skin have been established as alternatives to the traditional tooth-based method in bear species. However, the collection of these tissues is limited to captured or dead individuals. In the present study, we established the first hair-based age estimation model based on DNA methylation levels in brown bears, aiming for future application to less-invasively obtained hair of wild individuals. We performed bisulfite pyrosequencing and measured the methylation levels of hair root DNA. The methylation levels of cytosine-phosphate-guanine sites adjacent to the genes VGF, KCNK12, and ELOVL2 were found to be correlated with age. The best age estimation model used three cytosine-phosphate-guanine sites adjacent to two genes, VGF and KCNK12, with a mean absolute error of 3.2 years and median absolute error of 2.2 years after leave-one-out cross-validation. Our method is innovative because of the simplicity of sampling and the lack of requirement to capture bears. If this method can be widely applied to hair samples obtained in the field, the age structure of wild populations can be understood, contributing to ecological research, conservation, and management of bear species.

The Tsushima leopard cat (Prionailurus bengalensis euptilurus), an endangered feline endemic to Tsushima Island, Japan, faces critical threats due to its small and isolated population. Understanding its demographic history and genetic differentiation from continental populations is essential for conservation planning. In this study, we performed whole-genome sequencing of four Tsushima individuals and applied demographic inference methods, including pairwise sequentially Markovian coalescent (PSMC) and Sequentially Markovian Coalescent (SMC++), to reconstruct the historical effective population size (Ne) and estimate divergence times. PSMC revealed a population expansion between 200,000 and 100,000 years ago, followed by a long-term decline. SMC++ inferred a continuous decline and estimated that the divergence from the Korean leopard cat population occurred approximately 30,000-20,000 years ago. Genetic diversity analysis showed that the Tsushima population has significantly lower heterozygosity and higher inbreeding levels than continental populations. Genetic clustering based on genome-wide SNPs indicated that the Tsushima population is genetically closest to the Korean population, forming a northern cluster distinct from southern populations, such as Borneo and the Malay Peninsula. These findings provide valuable insights into the evolutionary history and genetic status of the Tsushima leopard cat and contribute critical data for the design of future conservation strategies targeting this unique insular lineage.

The cognition of large farm animals is important for understanding how cognitive abilities are shaped by evolution and domestication. Valid testing methods are needed with the development of cognitive studies in more species. Here, a step-by-step method for training four naïve domestic goats to use a touchscreen in cognitive tests is described. The goats made accurate touches smoothly after training. Follow-up tests were conducted to confirm that they could do cognitive tests on a touchscreen. In the pilot test of odd-item search, all the goats had above-chance level performances in some conditions. In the subsequent odd-item search tasks using multiple novel stimulus sets, one goat could achieve the criterion and complete several stages, and the results showed a learning effect. These suggest a potential ability to learn the rule of odd-item search. Not all goats could pass the criteria, and there were failures in the transfer, indicating a perceptual strategy rather than using the odd-item search rule. The experiment confirmed that goats could use the touchscreen testing system for cognitive tasks and demonstrated their approaches in tackling this problem. We also hope that these training methods will help future studies training and testing naïve animals.

Measuring the heart rate of sea turtles is important for understanding their physiological adaptations to the environment. Non-invasive methods to measure the electrocardiogram (ECG) of sea turtles have been developed by attaching electrodes to their carapace. However, this method has only been applicable to sea turtles with sparse keratin on their shell surfaces, such as loggerhead turtles, and it is difficult to detect heartbeats in sea turtles with dense keratinous scutes, including green sea turtles. Here, we explored the electrode placements on the plastron that can be applied to ECG measurement in green turtles. ECG signals were checked using a handheld ECG monitor at three sets of electrode placement on the plastron. When ECG signals could be detected, they were measured in the water tanks for several days to confirm the clarity of the ECG signals. Of the 29 green turtles, when the negative electrode was placed near the neck area of the plastron, clear ECG signals were obtained in nine individuals (39.1%), whereas ECG signals were not detected at any placements in four individuals (17.4%). Furthermore, in the water tank experiments, continuous ECG signals were successfully recorded by attaching a negative electrode near the neck: almost noiseless clear ECG signals even during moving in seven out of ten individuals and slightly weak and noisy signals in other individuals. The measured heart rate of ten individuals during resting was 8.6 ± 2.9 (means ± s.d.) beats min-1 and that during moving was 12.2 ± 4.7 beats min-1, similar to those reported in a previous study involving the insertion of electrodes inside the body. Therefore, for measuring the ECG of green turtles, the negative electrode should be placed closer to the neck, and the positive and earth electrodes should be placed to the lower left of the plastron. Although the selection of suitable individuals for measurements is required, this heart rate measurement method will contribute to a better understanding of the physiological status of sea turtles with dense keratinous scutes, including green turtles.

Live pet trade has become one of the greatest threats to wild primate populations. Many primates were imported to Japan, and the country is considered to be a large pet primates market. Among the primates, slow lorises (Nycticebus spp.) were among the most popular species for live pet trade. However, there is not much awareness in Japan about the problems associated with live pet trade, especially among the young generation. In this study, a comic book about slow lorises was created, and its effectiveness as a teaching material for young people was evaluated. The participants, who answered an online survey, included 596 high school students from two high schools in Osaka, Japan. The participants accessed a comic book, short text, or long text, which served as teaching materials, and answered several questions before and after reading the materials such as their experience with pet primates and awareness of the problems. The results revealed that although the participants’ awareness related to infectious diseases, animal welfare, and conservation increased after reading any of the three teaching materials, the comic book did not increase their awareness more than the texts. Approximately 75 % of the participants found each of the materials interesting. Furthermore, approximately between 32.0 and 40.9% of respondents were willing to share information directly with others and between 14.5 and 16.5% of those with SNS (Social Network Service). No differences were found among the three conditions. In addition, while actual experience with primate pets prevented them from promoting awareness about the problem, their level of interest toward animals and experience with primate pets in SNS did not reveal such an effect. These results suggest the importance of providing information, but effective ways to convey information requires further investigation.

Little is known about the social behavior of pygmy slow lorises, in particular, the social relationships of same-sex individuals have rarely been investigated. The Slow Loris Conservation Center was built at the Japan Monkey Center to enhance the welfare of confiscated slow lorises, promote their conservation, improve public education, and perform scientific research on the species. In the course of improving housing conditions, several same-sex pairs of pygmy slow lorises were formed. We monitored their behaviors and fecal glucocorticoid metabolite (FGM) levels to understand whether male same-sex pairings could be a feasible management strategy. The subjects were 10 male and 6 female lorises for comparison, all of whom were over 5 years old. We successfully formed five pairs of male lorises after eight formation attempts. Male pairs initially showed some aggressive behaviors; however, the rate decreased approximately 10 days after introduction. All of the male pairs eventually exhibited extensive affiliative social behaviors, including allogrooming and social play, during the dark (active) phase, and sleep site sharing during the light (inactive) phase. The rate of sleep site sharing during the light phase was higher than expected, suggesting that the pairs preferred to stay near each other. There was no evidence of increased stress after a long period of male-male social housing. Female same-sex pairs and male-female pairs demonstrated a high level of affiliative behaviors right after the introduction. These results highlight the flexibility and high sociability of this species and indicate that such same-sex pairings are a feasible option for their social management.

Despite increasing interest in the behavior of zoo animals, studies of nocturnal behavior of zoo animals are limited. In this study, we investigated the relationship between parturition, season, and the sleep-related behaviors in captive reticulated giraffes to better understand the nocturnal life in giraffes. The subjects were two adult reticulated giraffes living in Kyoto City Zoo, Japan. Observations were made via an infrared camera that was mounted in the indoor enclosure between June 2007 and August 2009. We analyzed video clips that were recorded between 16:30 and 09:00 the next morning, over a total of 199 days. Sleep-related behaviors were classified into two categories based on the posture of the giraffes; recumbent posture and paradoxical sleep. We also recorded the laterality of recumbent posture, which was coded based on the direction of the legs against the torso (right or left). Seasonal differences in sleep behaviors between summer and winter were observed in both individuals. They tended to start to lie down earlier in the winter than in the summer. Parturition also affected the behaviors as both individuals decreased the behaviors before and after the parturition of the female. Additionally, the female lay on her left side less frequently than her right when resuming a recumbent posture in the pre-parturition period, while such laterality was not observed in the baseline and post-parturition period. These results suggested that season and parturition are important factors for determining the sleep-related behaviors in giraffes. Further studies are needed to understand how these changes in sleep affect other welfare parameters.

Understanding how social relationships affect long-term stress is important because stress has a profound impact on the welfare of animals and social relationships often exert a strong influence on their stress responses. The purpose of this study was to investigate the relationship between social behaviors and long-term stress levels as assessed by hair cortisol (HC) concentration. The subjects were 11 chimpanzees living in an all-male group (divided into two sub-groups) in Kumamoto Sanctuary, Kyoto University, Japan. Behavioral data were collected between December 2014 and March 2015. The total observation time was 129h. Hair samples were collected in late March and early April 2015, and cortisol was extracted from the hair and measured with enzyme immunoassay. The hair growth rate was estimated to be 1.33±0.06cm/month. The results revealed that there was a positive correlation between the rate of receiving aggression and HC levels. We also found a significant negative correlation between the balance between giving and receiving grooming (grooming balance index: GBI), which was calculated by subtracting the rate with which grooming is given from that with which it is received, and the rate of receiving aggression and between the GBI and HC levels. Thus, individuals receiving higher levels of aggression also tended to give grooming for relatively long periods compared to the time they were being groomed. In contrast, the rate of initiating aggression did not have a relationship with either HC levels or any measure of social grooming. We did not find social buffering effects, as there was no correlation between mutual social grooming and HC levels. These results show that not only aggressive interactions but also overall social situations in which animals do not have balanced relationships with others might result in the long-term elevation of cortisol levels in captive male chimpanzees.