At a permanent pair territory of Jungle Crow Corvus macrorhynchos in Tokyo, a total of 454 morning and 95 night return-flights from communal roosts were recorded through the seasons, 1972-'79. The distances from roosts to territory were 1km in summer and 4km in winter. The arrival time to territory was analysed with regard to month, season, and weather. Usual morning arrival from roost to territory was recorded from 0 to 70 minutes before sunrise. They were average 26-27 minutes before sunrise in spring or autumn, about 21 minutes in short-nighted summer and about 30 minutes in longnighted winter, thus probably correlated with the length of daytime feeding period. But, in spring, especially April, the breeding activity may suppress the above daylength factor, awaking early for feeding even during short-nighted period, thus consuming energy owing to short night rests. The morning movement was earliest and variable in fine weather, then in cloudy condition and was latest and least variable on rainy days, which suggested bird's inactiveness in rainy weather. The night returns were recorded from August to April, the peak season of night returns being November to January (52% of all records) prior to breeding, and 58% were recorded on fine, 28% on cloudy and 12% on rainy days. As for time, 73% were recorded between 1-3a.m., 16% 23-24p.m., 7% 20-22p.m. and 4% after 4a.m. It is not clear whether this is a natural behavior or is peculiar to crows of cities, but should reflect the territorial adherance before they acquire their stable breeding conditions.
The original data of morning returns to territory from roost were statistically calculated by means of multiple range test and T-test, to analyse, 1. Inter-seasonal test by weather 2. Inter-weather test by seasen 3. Inter-weather test by month and 4. Inter-menstual test by season. These showed significant differences of winter return times from those in other seasons (spring and summer), fine-weather return times by seasen and month, while least variable were times in rainy weather.