Association of maternal genetics with the gut microbiome and eucalypt diet selection in captive koalas.

Background: Koalas, an Australian arboreal marsupial, depend on eucalypt tree leaves for their diet. They selectively consume only a few of the hundreds of available eucalypt species. Since the koala gut microbiome is essential for the digestion and detoxification of eucalypts, their individual differences in the gut microbiome may lead to variations in their eucalypt selection and eucalypt metabolic capacity. However, research focusing on the relationship between the gut microbiome and differences in food preferences is very limited. We aimed to determine whether individual and regional differences exist in the gut microbiome of koalas as well as the mechanism by which these differences influence eucalypt selection. Methods: Foraging data were collected from six koalas and a total of 62 feces were collected from 15 koalas of two zoos in Japan. The mitochondrial phylogenetic analysis was conducted to estimate the mitochondrial maternal origin of each koala. In addition, the 16S-based gut microbiome of 15 koalas was analyzed to determine the composition and diversity of each koala's gut microbiome. We used these data to investigate the relationship among mitochondrial maternal origin, gut microbiome and eucalypt diet selection. Results and Discussion: This research revealed that diversity and composition of the gut microbiome and that eucalypt diet selection of koalas differs among regions. We also revealed that the gut microbiome alpha diversity was correlated with foraging diversity in koalas. These individual and regional differences would result from vertical (maternal) transmission of the gut microbiome and represent an intraspecific variation in koala foraging strategies. Further, we demonstrated that certain gut bacteria were strongly correlated with both mitochondrial maternal origin and eucalypt foraging patterns. Bacteria found to be associated with mitochondrial maternal origin included bacteria involved in fiber digestion and degradation of secondary metabolites, such as the families Rikenellaceae and Synergistaceae. These bacteria may cause differences in metabolic capacity between individual and regional koalas and influence their eucalypt selection. Conclusion: We showed that the characteristics (composition and diversity) of the gut microbiome and eucalypt diet selection of koalas differ by individuals and regional origins as we expected. In addition, some gut bacteria that could influence eucalypt foraging of koalas showed the relationships with both mitochondrial maternal origin and eucalypt foraging pattern. These differences in the gut microbiome between regional origins may make a difference in eucalypt selection. Given the importance of the gut microbiome to koalas foraging on eucalypts and their strong symbiotic relationship, future studies should focus on the symbiotic relationship and coevolution between koalas and the gut microbiome to understand individual and regional differences in eucalypt diet selection by koalas.

Dogs (Canis familiaris) Gaze at Our Hands: A Preliminary Eye-Tracker Experiment on Selective Attention in Dogs.

Dogs have developed a social competence tuned to communicate with human and acquire social information from body signals as well as facial expressions. However, less is known regarding how dogs shift attention toward human body signals, specifically hand signs. Comparison among visual attentional patterns of dogs toward whole body of human being, conspecifics, and other species will reveal dogs' basic social competences and those specialized to inter-species communication with humans. The present study investigated dogs' gazing behaviors in three conditions: viewing humans with or without hand signs, viewing conspecifics, and viewing cats. Digital color photographs were presented on a liquid crystal display monitor, and subject dogs viewed the images while their eyes were tracked. Results revealed that subjects gazed at human limbs more than limbs within conspecific and cat images, where attention was predominately focused on the head and body. Furthermore, gaze toward hands was greater in the human hand sign photos relative to photos where human hand signs were not present. These results indicate that dogs have an attentional style specialized for human non-verbal communication, with an emphasis placed on human hand gestures.

Current husbandry situation of red pandas in Japan.

The red panda (Ailurus fulgens) is an endangered semi-arboreal folivore with a specialized diet of bamboo leaves. Zoos worldwide maintain red pandas under a variety of housing environments and husbandry procedures that may affect the reproductive success and longevity of captive red pandas. The aims of the present study were to investigate how red pandas are kept in Japan and to obtain useful insights to increase their longevity by comparing the results from a questionnaire sent to Japanese zoos and those from a previous survey conducted in other countries. We received responses from 42 out of 52 zoos, holding a total of 219 individual red pandas, in Japan. The age-sex distribution indicated that red panda populations in Japan need close attention to be maintained sustainably. Of the husbandry aspects surveyed, the number of individuals in the same zoo, enclosure size, and the frequency of bamboo feeding factors indicated to affect reproductive success. Frequent monitoring of body weight, implementation of husbandry training, and bamboo feeding were also suggested as the reasons for the longevity of red pandas in Japan. Zoos were provided with sufficient physical features in on-exhibit enclosures, close monitoring for health status, and proper feeding, but other aspects of husbandry such as enclosure size and structures in off-exhibit spaces were insufficient and might compromise animal welfare.

Video preference assessment and behavioral management of single-caged Japanese macaques (Macaca fuscata) by movie presentation.

Movie presentation can act as an enrichment technique for nonhuman primates, who also show preferences for certain contents. This study investigated the video preferences and effects of movies on behavioral abnormalities in single-caged Japanese macaques. When movie rewards were provided for subjects' touch responses, the subjects maintained the touch responses during 40 2-hr sessions. Although repeated presentation of 1 stimulus set decreased the subject's touch response, changing the stimulus set led to recovery of this response. The subjects showed clear preferences, consistent across 2 different stimulus sets, for movies showing humans or animation (61.1% of total duration). Subjects consistently played movies both with and without their preferred content. The availability of a variety of contents might be important for attracting subjects' interest. The frequency with which monkeys engaged in abnormal behaviors decreased in the experimental (20.9%) and the postexperimental (25.6%) periods compared with the preexperimental period (33.5%). Movie presentations could keep attracting the interest of single-caged monkeys in their visual environment, ameliorating their behavioral abnormalities for some time. In summary, social experience during infancy might influence Japanese macaques' movie preferences.

Contrafreeloading and the value of control over visual stimuli in Japanese macaques (Macaca fuscata).

Contrafreeloading, which means that animals work for food even though identical food is freely available, has been reported in animals' feeding behavior. This phenomenon has been assumed to be explained by the information primacy model, in which the information about a food resource as well as the food itself is valuable for animals. This study confirmed a contrafreeloading-like phenomenon using movies as rewards rather than food in Japanese macaques (Macaca fuscata) and investigated the motivational system that exists behind contrafreeloading. In the experiment, movies that were presented dependently on subjects' responses (earned movies) and movies that were presented automatically (free movies) were supplied simultaneously. The subjects continued to make responses to obtain the presentation of the earned movies although identical movies were available as free movies. These results provide the first evidence of contrafreeloading that occurs with movie rewards. The motivation maintaining the contrafreeloading behavior for movies may be control over the environment according to the competence theory.