Japanese Journal of Zoo and Wildlife Medicine Vol. 21(2016) No. 2

The gastrointestinal parasitic helminth fauna of 55 alien Pallas's squirrels (Callosciurus erythraeus) from the Uto Peninsula, Kumamoto, Japan, exterminated as part of an eradication program in October, 2010, were surveyed for the present study. Only four nematode species were detected, including one dominant strongylid, Strongyloides callosciureus (prevalence: 49.1%; abundance: 2.13 ± 0.66), and three other fragmental species, Brevistriata callosciuri, Capillariidae gen. sp. and Rictularia cristata (prevalence: 0.18%–0.55%; intensity: 1–3). The ratio of the mean to variance and the k-value of the negative binomial distribution pattern on the abundance of S. callosciureus were 0.089 and 0.283 (0.387 and 0.278 in male and female hosts), respectively. Relationships between the abundance of the strongylid and relevant factors such as individual host traits (sex, age, and body size) were examined using a generalized linear model. Male hosts harbored significantly more worms than the females in the optimal model. These sexual differences are attributable to the behavioral features of the host.

The prevalence of Sarcocystis cyst (sarcocyst) in muscles from 63 heads of Sika deer (Cervus nippon centralis) and 30 heads of Japanese wild boar (Sus scrofa leucomystax) was investigated. Sarcocysts were detected in 95.2% of deer and 50.0% of wild boar. Immunostaining with antiserum against the toxicity protein of Sarcocystis fayeri, a cause of food poisoning due to raw horsemeat, showed a positive reaction around bradyzoites in the sarcocysts. Hepatozoon sp. was also found from boar muscles in this survey. Phylogenetic analysis of 18S ribosomal DNA indicated Sarcocystis isolates from Sika deer were classified mainly into five groups. Moreover, we suggested Hepatozoon isolates from wild boars might be host specific.

The comb is a good indicator of physical condition in male birds. We monitored the seasonal changes in supraorbital comb characteristics with visual assessments and fecal testosterone concentrations by enzyme immunoassay in three captive male Svalbard rock ptarmigans (Lagopus muta hyperboreus). Although there were interindividual variations, the size and redness increased from February to August; i.e., before and during breeding season. The fecal testosterone levels increased markedly between May and June, and declined sharply from late June. The color simultaneously changed from deep to pale red but size was kept until testosterone concentrations fell to baseline. We suggest that changes occurring in supraorbital comb, especially its redness, reflect testicular activity and may be useful indicators for captive breeding of this species.