Shin-ichi Hayama

Low blood cell counts in wild Japanese monkeys after the Fukushima Daiichi nuclear disaster

In April 2012 we carried out a 1-year hematological study on a population of wild Japanese monkeys inhabiting the forest area of Fukushima City. This area is located 70 km from the Fukushima Daiichi Nuclear Power Plant (NPP), which released a large amount of radioactive material into the environment following the Great East Japan Earthquake of 2011. For comparison, we examined monkeys inhabiting the Shimokita Peninsula in Aomori Prefecture, located approximately 400 km from the NPP. Total muscle cesium concentration in Fukushima monkeys was in the range of 78–1778 Bq/kg, whereas the level of cesium was below the detection limit in all Shimokita monkeys. Compared with Shimokita monkeys, Fukushima monkeys had significantly low white and red blood cell counts, hemoglobin, and hematocrit, and the white blood cell count in immature monkeys showed a significant negative correlation with muscle cesium concentration. These results suggest that the exposure to some form of radioactive material contributed to hematological changes in Fukushima monkeys.

Concentration of Radiocesium in the Wild Japanese Monkey (Macaca fuscata) over the First 15 Months after the Fukushima Daiichi Nuclear Disaster

Following the massive earthquake that struck eastern Japan on March 11, 2011, a nuclear reactor core meltdown occurred at the Fukushima Daiichi Nuclear Power Plant, operated by Tokyo Electric Power Company, and was followed by the release of large amounts of radioactive materials. The objective of this study was to measure the concentration of radiocesium 134Cs and 137Cs in the muscle of Japanese monkeys (Macaca fuscata) inhabiting the forest area of Fukushima City and to determine the change in concentration over time as well as the relationship with the level of soil contamination. Cesium concentrations in the muscle of monkeys captured at locations with 100,000–300,000 Bq/m2 were 6,000–25,000 Bq/kg in April 2011 and decreased over 3 months to around 1,000 Bq/kg. However, the concentration increased again to 2,000–3,000 Bq/kg in some animals during and after December 2011 before returning to 1,000 Bq/kg in April 2012, after which it remained relatively constant. This pattern of change in muscle radiocesium concentration was similar to that of the change in radiocesium concentration in atmospheric fallout. Moreover, the monkeys feed on winter buds and the cambium layer of tree bark potentially containing higher concentrations of radiocesium than that in the diet during the rest of the year. The muscle radiocesium concentration in the monkeys related significantly with the level of soil contamination at the capture locations.

Dominant Parasympathetic Modulation of Heart Rate and Heart Rate Variability in a Wild-Caught Seabird

Heart rate (HR) and heart rate variability (HRV) provide noninvasive measures of the relative activity of the parasympathetic nervous system (PNS), which promotes self-maintenance and restoration, and the sympathetic nervous system (SNS), which prepares an animal for danger. The PNS decreases HR, whereas the SNS increases HR. The PNS and SNS also contribute to oscillations in heartbeat intervals at different frequencies, producing HRV. HRV promotes resilience and adjustment capacity in the organism to intrinsic and extrinsic changes. Measuring HRV can reveal the condition and emotional state of animals, including aspects of their stress physiology. Until now, the functioning of the PNS and SNS and their relationship with other physiological systems have been studied almost exclusively in humans. In this study, we tested their influence on HR and HRV for the first time in a wild-caught seabird, the streaked shearwater (Calonectris leucomelas). We analyzed electrocardiograms collected from birds carrying externally attached HR loggers and that received injections that pharmacologically blocked the PNS, the SNS, or both, as well as those that received a saline (sham) injection or no injection (control). The PNS strongly dominated modulation of HR and also HRV across all frequencies, whereas the SNS contributed only slightly to low-frequency oscillations. The saline injection itself acted as a stressor, causing a dramatic drop in PNS activity in HRV and an increase in HR, though PNS activity continued to dominate even during acute stress. Dominant PNS activity is expected for long-lived species, which should employ physiological strategies that minimize somatic deterioration coming from stress.

Morphological Changes of Female Reproductive Organs of Japanese Monkeys with Reproductive Conditions

Macroscopic and histological changes were examined on the female reproductive organs of Japanese monkeys (Macaca fuscata) with varying reproductive status in enclosed and provisioned troops. The weight and size of reproductive organs are described. The size of uterus declined in 2–3 months after parturition. The number of parturition was roughly estimated by degrees of sclerosis in myometrial vessels. The nipple length of parous animals was longer than that of nulliparous ones. The bilateral difference in the length (more than 3 mm) between nipples indicated the experience of nursing. Interpreting ovaries on the basis of macroscopic examination alone was less precise. The present results suggested that the female sexual maturity and the experience of nursing can be estimated by the measurement of reproductive organs in the Japanese monkey.

Small head size and delayed body weight growth in wild Japanese monkey fetuses after the Fukushima Daiichi nuclear disaster

To evaluate the biological effect of the Fukushima Daiichi nuclear disaster, relative differences in the growth of wild Japanese monkeys (Macaca fuscata) were measured before and after the disaster of 2011 in Fukushima City, which is approximately 70 km from the nuclear power plant, by performing external measurements on fetuses collected from 2008 to 2016. Comparing the relative growth of 31 fetuses conceived prior to the disaster and 31 fetuses conceived after the disaster in terms of body weight and head size (product of the occipital frontal diameter and biparietal diameter) to crown-rump length ratio revealed that body weight growth rate and proportional head size were significantly lower in fetuses conceived after the disaster. No significant difference was observed in nutritional indicators for the fetuses’ mothers. Accordingly, radiation exposure could be one factor contributed to the observed growth delay in this study.

Analysis of body mass changes in the Black-Headed Gull (Larus ridibundus) during the winter

During the autumn migration of many waterfowls, body mass is lowest upon arrival at the wintering area and gradually increases during the winter. Consequently, body mass is highest before the spring migration. We studied the pattern of body mass changes in the Black-Headed Gull (Larus ridibundus) from December 2010 to December 2016 in the Shinhama area of Chiba, Japan. Based on 327 captured animals, body mass increased during the wintering period, but tended to decrease before migration. In 2014–2016, a muscle mass reduction in females was observed, explaining the change in body mass. However, the observed weight loss may be caused by many factors, which may be related to the migratory ecology of the regional population.

Body Mass Changes of Japanese Rock Ptarmigan Lagopus Mutus Japonicus in Captivity

Abstract Changes in body mass of a pair of captive Japanese Rock Ptarmigan Lagopus mutus japonicus and their chicks were measured using an automatic weighing system at Omachi Alpine Museum from 13 January 1995 to 29 October 1996. The males body mass decreased gradually in late April, the beginning of the breeding season, but returned to the normal level in the fall. In contrast, the females body mass increased rapidly from late April onward, peaking in late May, just before the egg-laying period. Thereafter, the females body mass decreased throughout the egg-laying, incubation, and early brooding periods, but began to increase again in the fall. In 1996, four chicks were successfully reared and their body mass increased linearly during the first 60 days after hatching, followed by a milder increase.

Epizootic of sarcoptic mange in raccoon dogs (Nyctereutes procyonoides) in relation to population density

To examine outbreaks of mange in raccoon dogs (Nyctereutes procyonoides) with respect to population density, we analyzed camera trap videos, and isolated mites from raccoon dog carcasses. In a camera trapping survey, we categorized the skin condition of raccoon dogs, and used a number of independent videos to calculate the relative abundance index (RAI). The RAI of raccoon dogs with alopecia increased following an increase in the RAI of those without alopecia. Among 27 raccoon dog carcasses, 12 showed mange-compatible skin lesions. Sarcoptes scabiei was isolated from 11 of these raccoon dogs, indicating that sarcoptic mange was endemic in our study area. Therefore, a high relative population density may be a factor underlying epizootics of sarcoptic mange in raccoon dogs.

Infestation of introduced raccoons (Procyon lotor) with indigenous ixodid ticks on the Miura Peninsula, Kanagawa Prefecture, Japan

Since the raccoon (Procyon lotor) was introduced to Japan, studies have established that they are infested with native Japanese tick species. However, the quantity of ticks infesting raccoons is unknown. We conducted a survey of ticks on invasive raccoons captured on the Miura Peninsula, Kanagawa Prefecture, Japan, from April 2015 through June 2016 to determine the species of ticks and to quantify the intensity of tick infestation in order to obtain basal information related to the ecology of host–parasite relationships among indigenous tick species and an alien mammalian species. We collected and identified 15,931 ticks of two genera and six species, namely, Haemaphysalis flava, H. megaspinosa, H. longicornis, H. japonica, Ixodes ovatus, and I. tanuki, from 100 out of 115 raccoons. The dominant tick species was H. flava (96.8%) and individuals were mainly adults. Seasonal patterns of infestation intensity of adults and nymphs peaked in the autumn and winter and decreasing in the late spring and summer, May to August, while larvae peaked in August. Our results indicated that host–parasite relationships between invasive raccoons and Japanese tick species, especially H. flava, were established in Kanagawa Prefecture. The ticks infest invasive raccoons for their blood-meal and also for overwintering. The results of this study extend our understanding of the ecology of tick-borne diseases.

Disaster Preparedness for Pets

URI, 71% and 54% of cats developed diarrhea, and 91% and 83% of cats had at least one disease in 2011 and 2012, respectively. Uses of multiple drug administration (more than five drugs) was associated with prolonged URI and diarrhea. Multiple antibiotics, antihistamines, interferon, and steroids were associated with relapse of and prolonged URI. Conclusion: The incidence of disease in cats at the shelter was high. Developing a standardized treatment protocol for commonly observed diseases at Japanese animal shelters to prevent and control diseases, to promote animal welfare, and to protect public health in the face of future disasters is overdue.