The vocalizations of mature feral cats, Felis catus, were analyzed based on sound spectrograms and behavioral interactions, focusing on sexual differences. Both males and females produced three distinct types of loud vocalizations during the breeding season: rutting cry, yowl, and mew. The rutting cry could be distinguished from the other two types by behavioral contexts and spectrographic features. The rutting cry was heard only during the breeding season, whereas the other two types were heard throughout the year. These results suggest the existence of a loud vocalization specific to the breeding season in feral cats. Males produced rutting cries more often than females.

View full abstract

The masticatory muscles and related apparatus of the hoary Rhizomys pruinosus and lesser bamboo rats Cannomys badius from Thailand, and the East African mole rat Tachyoryctes splendens from Ethiopia were morphologically examined and compared. The zygomatic arch was found to be robust in the two Asian species, with well-developed superficial, intermediate, lateral, and caudal parts of the deep layer of the masseter muscle. The temporal muscle was not well-developed in the hoary bamboo rat. The well-developed infraorbital foramen in the East African mole rat is consistent with the significant role of the medial part of the deep layer of the masseter muscle. These findings reveal that the Asian and African lineages are obviously different in terms of their masticatory systems, and indicate that the different taxa have evolved independently. These evolutionarily divergent taxa appear to represent examples of functional convergence in their similar adaptations to digging behavior and to a fossorial lifestyle.

View full abstract

The distribution of the spotted seal, Phoca largha, along the coast of Hokkaido was investigated, based on personal interviews, surveys of haul-out sites, and records and direct examinations of seals. Interviews conducted in 1997 along the entire coastline of Hokkaido, confirmed that spotted seals have been observed in all eight regions of the island. Incidental harvests by fishing nets and damage control kills were confirmed in seven and in three regions, respectively. Examinations were made of live and dead specimens, and of specimen records from between 1971 and 1998 (n=605), all obtained from Hokkaido University, aquariums and zoos. Specimen and documentary records were most common in regions where incidental harvests and damage control kills were reported. Seasonal and regional variations in seal distributions were observed. Incidental harvests, damage control kills, and strandings were most common during salmon harvest season (fall), sea ice season, and the weaning period, respectively. Sub-adults and adults were found in areas with seasonal sea ice, while immature seals were recovered from areas with little or no sea ice. The fewest seal sightings and no haul-out sites were reported from southern Hokkaido, probably because warm sea currents discourage seals from using this area.

View full abstract

Behavioral responses of wild-caught gray-sided voles Clethrionomys rufocanus to the odors of neighboring individuals and of strangers were observed in the laboratory. Differences between the sexes in behavioral responses to social odors are discussed in relation to social organization in the field. In a free ranging population in an early breeding season, females maintained mutually exclusive home ranges, whereas males held home ranges that overlapped with each other and covering the ranges of one or more females. Four pairs of neighbors and four pairs of strangers were taken from the population for each sex and behavioral response to social odor to be observed in the laboratory. Although we explored differences in several behavioral responses between sexes, no marked qualitative differences were observed; however, females tended to spend longer in the odorized terrarium than in the control terrarium, compared with males.

View full abstract

Niche segregation among three sympatric species of squirrels, Callosciurus notatus, C. caniceps and Sundasciurus lowii inhabiting a lowland dipterocarp forest was studied in the Ulu Gombak Forest Reserve, Selangor Darul Ehsan, Malaysia. Diurnal activity of the three species had two peaks. Sundasciurus lowii and C. caniceps were more restricted in vertical space, concentrated mainly at lower tree heights, whereas C. notatus was slightly less restricted. Sundasciurus lowii were more selective in their diet: bark was the main food item. The two Callosciurus spp. took a variety of food items, although fruit was the major component. The niche breadth values in diurnal activity patterns, vertical space uses, and food preferences revealed that C. notatus was a generalist compared with the other two species. Differences in selection of tree species rather than food item may be the main factors that determine niche occupancy for the three species of squirrels in the study area.

View full abstract

The distribution and density of noradrenergic (NA) and acetylcholinesterase-positive (AChE) nerves in the uterus of the young Japanese long-fingered bat were investigated using specific immunohistochemical and histochemical techniques. This species has an unusual reproductive mechanism during the immature period. An abundant number of NA and AChE nerves were found to be associated with blood vessels and smooth muscles in the myometrium. In addition, a number of AChE nerves ran in close association to the endometrium. These findings must be considered in relation to an improvement of the structure and function of the uterus of the bat as it progresses towards sexual maturity.

View full abstract