Postnatal growth and development of Apodemus semotus were investigated from birth, to day 90, in the laboratory. Morphometric measurements at birth, of both sexes combined, revealed body weight to be 2.09±0.17 g, mean head and body length to be 35.51±2.94 mm, mean tail length as 13.59±0.76 mm and mean hind foot length as 6.52±0.47 mm. Body weight was found to increase steadily until day 50, whereas the instantaneous growth rates of other measurements declined earlier. Head and body length increases declined to a minimum after day 40, that of tail length after day 45, of hind foot length after day 32, and of ear length after day 28. Although tail to body length ratio reached more than 100% on day 36 for males and on day 28 for females, no sexual differences were found in the growth rate of body weight (using the Gompertz equation), or of linear dimensions (using the logistic equation). Pinnae unfolded on days 2-3, the auditory meatus opened on days 12-14, and the eyes opened on days 14-16. Growth and development were divided into four periods: 1) neonate, days 0-6; 2) transition, days 7-14; 3) socialization, days 15-24 ; and 4) juvenile, day 25 to sexual maturity. In the field, the spring generation of juveniles grew quickly, whereas the autumn generation grew more slowly. Comparisons of the developmental pattern of A. semotus with those of other Apodemus species and of other species of related genera, revealed that the developmental pattern of A. semotus was broadly similar to that of Mus species and to those of some Rattus species.

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Field observations of gliding and quadrupedal locomotion in the Japanese giant flying squirrel Petaurista leucogenys were made at five shrine groves with different topographies, tree densities and canopy heights. The main mode of locomotion was gliding, although arboreal quadrupedal locomotion was preferred to gliding flight in forests with a canopy height of less than 10 m, presumably because gliding was not energetically advantageous. The mean horizontal length of glides varied from 17.1-33.1 m among the study areas. Short glides of less than 10 m were infrequent. The longest glide recorded was of 115 m, but such long distance glides were rare and normally limited to circumstances where no intervening trees were available. Even when long distance glides were topographically possible, the animals tended to repeat glides of less than 50 m. Squirrels were found capable of gliding at a glide ratio (horizontal distance/vertical drop) of 3.5, but such extremes were not normal. More typically, glide ratios were found to be within the range of 1-3. Both glide ratio and speed tended to increase in longer glides, and horizontal gliding speeds ranged from 7.0-13.3 m/sec. The reasons why glides rarely approach the maximum capacity are discussed in relation to 1) wind velocity, 2) small home ranges, and 3) necessity of buffering landing impacts.

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