Flight distances were measured in the Dusky Thrush, Turdus naumanni, in winter. Predictive models relating flight distance of the thrush to environmental variables were developed and tested using stepwise multiple regression. The models, based on analyses of possible independent variables collected in 1984 and 1985, accounted for 54% and 82% of the variation in flight distance, respectively. The most important independent variables were location of the thrush (whether it was within 10 meters from the nearest shelter belt or not) and snow depth in 1984, and distances from the thrush to the nearest shelter belt and perch height in 1985. Longer flight distances were recorded further away from shelter belt. Snow fall made the flight distance shorter. Based on the multiple regression model in 1985, I predicted flight distance of thrushes and the time until they flew off for each distance from the shelter belt and showed that a thrush would stay a longer time before it flew off near shelter belts.
The effectiveness of "Birdershot" (a fumigant for repelling birds-active component: p-dichlorobenzene) as a bird repellent was assessed for captive feral pigeons, Columba livia in two-choice experiments. When food sites treated with and without (control) the fumigant were placed 10m apart, the pigeons preferred to feed at the non-treated food site. This effect lasted for a minimum of 8 days. However, when a food site treated with the fumigant was placed only 2.5m away from a non-treated food source, the pigeons showed no avoidance of the fumigated food site
We investigated the curious behaviour of Carrion Crows Corvus corone that make use of automobiles to crack walnuts. A typical sequence of the behaviour is : a crow puts a walnut in front of the automobile that is stopped by a traffic signal ; then the car run over the walnut and the crow eats the fragements of the walnut. This behaviour was frequently seen during the 21 months of the observation period and 43 occurrences of these were recorded in detail. The behaviour is found to consist of several variables : the procedure to get walnuts, the state of walnuts, the way to set walnuts on the road, time of the day, places, whether there are other crows around, how long to wait before abandoning, whether the crow tries to change the position of the walnuts, and the way the crow eats the cracked walnuts. The analyses of these variables suggest that the car-using behaviour of the crows is not accidental but rather systematic. Crows sometimes drop walnuts from more than 10 meters above the ground to crack them but some walnuts are too hard to crack by this method. We suggest the car-using behaviour is an alternative invention to crack walnuts that are too hard, or walnuts covered with pulp. Taken together, we consider the car-using beheviour of Carrion Crows to be intentional behaviour
The breeding ecology of the Varied Tit Parus varius was studied without nest boxes for two years and with nest boxes for ten years, at an eight ha. Secondary forest, with very few natural cavities, in central Japan. The breeding population consisted of only one pair each in the first two years. After setting out nest boxes, eight pairs bred in the first year and pro-duced 15 to 22 clutches in the following nine years. There was no relation-ship between the numbers of early and late broods in each year. Egg laying had a larger peak in frequency in early April and a smaller peak in mid-May. The starting day of nest building and the first egg-laying day significantly correlated to the January-March temperature. The length of incubation and fledging periods did not significantly correlate to brood size. Hatching success seemed to be higher in larger clutches. There was no significant correlation between number of nestlings and the length of nestling periods. The number of fledged young was significantly larger at eight nests of larger clutch size. Clutch sizes were significantly larger in early (6.35) than late (5.98) seasons. In successful nests, with one or more fledged young, more young fledged at the nests with larger clutches. Mean nest density was 1.63/ha, and many pairs foraged out of the research (nest) area. Mean distance between nests was 56 m and the closest two was 15m away from each other. New nest boxes were preferred significantly more, and such behavior seemed adaptive to escape nest predation.