For the conservation of forest frogs, it is important to conserve not only water sites for breeding but also forests for living in the non-breeding season. Therefore, the two species of brown frogs (Rana japonica and R. ornativentris) common to Japan were surveyed for their dispersal capability and the range of activity in the non-breeding season. The survey was conducted 16 times in forests on undeveloped land (about 28 ha) of the Tama Hills by the capture-and-mark method. The migrating distances were calculated from the sites of capture and spawning. As a result, 90% of the individuals were within the range of 200 to 270m (R. japonica) and 330 to 390m (R. ornativentris). The maximum distance was about 500m and both species were found capable of migrating at least 500m. The migrating distances of recaptured individuals indicated that both species have specific summer habitat. Yearlings especially of both species grow rapidly between summer and fall in the fprests. R. ornativentris was only rarely captured at the edge of the forest. The study demonstrated that the forest is the main habitat and main dispersion route for R. ornativentris in the non-breeding season. We discuss the conservation of both species from the viewpoint of landscape ecology.

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A mark-recapture study of the fresh water turtle Chinemys reevesii was conducted on a small (190 ha) island, Ishima Island, off the east coast of Shikoku to learn the demographic characteristics of an insular turtle population. Most of the Chinemys reevesii on the island were marked, yielding a reliable estimate of population size (1179 turtles per 15 ha aquatic habitats). The estimated sex ratio of the turtles in the younger age class (3-6yr) was essentially equal, slightly skewed toward males in a higher age class, and significantly male-biased in the older age class (>12yr). A significantly female-biased sex ratio among the turtles found dead was compatible with the male-biased sex ratio in adult turtles. Possible physiological and ecological factors for change in sex ratio with age are discussed with consideration of the insular environment.

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The male and female karyotypes were examined for 10 specimens of the Chinese soft-shelled turtle, Pelodiscus sinensis, from the main islands of Japan and Taiwan by the bone marrow air-dry technique. One specimen of Dogania subplana was also examined karyologically. Although both P. sinensis and D. subplana had 2n=66 chromosomes, they showed an interspecific variation in chromosome morphology. No karyotypical differences were evident between the Japanese and Taiwanese samples of P. sinensis, or within either of them. Comparisons of the present results with previously reported trionychine karyotypes indicate that there are some interspecific and intraspecific variations in centromeric positions of several macrochromosome pairs in this subfamily.

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The role of visual and chemical cues of conspecifics in the growth of head width was experimentally tested in Hynobius retardatus larvae reared under group and solitary conditions. In the former, the head width of the larvae increased proportionally in the presence of visual, chemical, and visual plus chemical cues, whereas such a morphological change was not apparent with similar cue treatments in solitary larvae. It was concluded that both visual and chemical cues from other conspecific individuals induced the wider head shape in H. retardatus larvae.

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In order to ascertain formation of lines of arrested growth (LAGs) in anuran larvae, cross-sections of long bones in overwintered tadpoles and juveniles of Rana catesbeiana were observed. However, no LAGs were evident in these individuals, although we could observe clear LAGs in adults treated in the same way. The result contrasts to those reported for urodelan larvae. We discuss the causes of this phenomenon on the assumption that the absence of LAGs in tadpoles is common to other anurans as well.

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Innate responses to prey chemicals, antipredator responses, and prey-handling behavior of a Madagascan colubrid snake, Leioheterodon madagascariensis, were experimentally examined. In a chemical test, ingestively naive hatchlings flicked their tongues frequently to the chemicals prepared from the animal taxa included in their natural diets, suggesting the presence of innate chemical prey preference. In a second test, three different types of stimuli were presented to elicit antipredator responses of the hatchlings. In a nonmoving stimulus session, only a single snake struck and exhibited characteristic displays such as body flattening, neck flattening, head elevation, and jerk. In a moving stimulus session, either no specific responses or a simple flight response was exhibited. In a tactile stimulus session, the above characteristic displays were frequently exhibited. Among these, lateral neck tilting posture accompanying head elevation and neck flattening was unique to L. madagascariensis. In a third test, five types of prey animals were offered to juveniles to examine the effects of prey size and type on prey-handling behavior, but no such effects were detected. Direction of ingestion seemed to depend on initial bite position. Constricting behavior was observed only in a single trial. All but one prey were swallowed alive. This inflexibility of prey-handling methods in the juvenile snakes may reflect the characteristics of generalist feeders, which require ontogenetic experiences to handle prey efficiently. Although L. madagascariensis is considered to have well-developed Duvernoy's glands with enlarged, posterior maxillary teeth, the gland secretion did not seem to cause rapid death of prey.

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The habitat choice of tadpoles of seven anuran species with respect to light and dark phases was studied using a choice tank with a simulated pond edge. In each trial, which lasted for 12hrs, twenty freshly collected tadpoles (Gosner stage 32-38) of a given species were used. After introducing tadpoles into the choice tank, their number at the surface, up the water column, and on the substrate was recorded at half-hour intervals. Four trials each for day and night were conducted for each species. Tadpoles of Rana curtipes, Rana cyanophlyctis, and Rana temporalis, which possess a ventral mouth, predominantly occupied the substrate zone, whereas those of Bufo melanostictus, Polypedates maculates, and Rana tigrina, which have an antero-ventral mouth, utilized both substrate and column zones but with a clear preference for the substrate zone. Within the substrate zone, the number of tadpoles of B. melanostictus, P. maculatus, R. temporalis, and R. tigrina was greater at night than in the daytime, whereas the opposite was true for R. curtipes. Of these five species response for day-night changes was prominent in P. maculatus. It is unclear whether variation in the number of tadpoles with respect to day and night is due to changes in the light intensity or temperature or oxygen levels. The tadpoles of R. cyanophlyctis did not show any response to day-night changes. On the other hand, the tadpoles of Microhyla ornata, which possess an antero-dorsally placed and highly simplified mouth (devoid of teeth) preferred the surface (64%) and column (28%) zones in both light and dark phases. The tadpoles of M. ornata are not easily spotted despite their surface occupancy due to their transparent appearance. The present study shows the existence of diversity in the microhabitat choice of the anuran tadpoles that correlates well with their morphological characteristics.

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