Out of a stock of the Plymouth Rock of 83-86% broodiness, three cocks which were not made broody by Prolactin-injection, and two hens of no and very weak broodiness, were selected. As the result of 5 years (1950-1954) of interbreeding of these five parental birds and their offsprings, a total of 129 hens were obtained. Of these hens, only five showed broodiness and all the rest were proved to be non-broody. Table 3 shows the percentages of broody hens occurred in each experimental year: the average rate of broodiness abruptly decreasing from original 84.5% to 3.8%. This result indicates the usefulness of prolactin-injection method for broodiness elimination in the domestic fowl.
By addition of 1956 observations, this report alters and supplements the resume 4-6 in the Misc. Rep., No. 7, p. 289 as follows: 1. Daily winter feeding range (rice paddies) of the flock roosting at Shinhama is delimited to 12km at the most by hills and scattered villages, while Koshigaya flock in a wide field (30km north of Shinhama) covers 20km, its periferal flocks meeting with those of Shinhama at the east of Tokyo. The feeding density ('lowest density') ranged from 0.4 to 4 birds per 1 ha. 2. Number of breeding pairs is given by each subarea studied, and the factors influencing the breeding density or preference are discussed. Chief factors may be: 1) enough nesting hollows, 2) type and age of vegetation, 3) structure of feeding area (at least some rice paddies) and 4) safety, etc. 3. Rice paddies become unfit for feeding area as the transplanted rice grows. This happens after the young of the 1st brood joined the flock and thus, only few early 2nd broods could be raised (Of the 19 nest-boxes, 17 were used in the 1st and 3 in the 2nd broods; more should be raised in city zone). Then the flock finally moves to the northern field. 4. As season advances, the condition of feeding ground changes by cultivation. Varieties in the insect fauna contained are shown by several sample collections made at different places and dates. Early in season, the ground spiders are dominant everywhere, but the most important food for raising young is the mole-cricket (Gryllotalpa), which is best sought in the paddies ready for rice transplantation in late June, when the nestlings grow and leave the nest. This may be said to support Lack's theory of anticipatory adaptation. 5. Preliminary consideration is given on the method of determining the ecological niche of the starling quantitatively. The quantity of food taken in a day (or an hour) within a unit area by a flock of starling occurring in a study area may be culculated by: L=Nnt/A×W When N: the number of individuals of the flock, n: the times (frequency) of occurrence of the flock in a day (or an hour), t: length of one feeding stay (mean) of the flock in a study area, W: quantity of food taken by one starling within a unit time (1min., 10min., etc.), A: dimension of study area. In breeding season N, n are substituted by the total number of individuals coming in from the colony. Discussion is given of the method of observation and culculation of t and W, and the method to estimate the quantity of food taken by parent birds was suggested from feeding behavior and the time of absence at the nest site.
It is to be desirable for plants feeding wildlife that they can retain their fruits, nuts, seeds, and berries as far as winter when food for wildlife is most scanty. Most plants usually shake off their fruits or nuts in this season. The Narrowleaf Firethorn, Pyracantha angustifolia Schneider, which is wellknown as a garden plant by the name of "Pyracanthas" can, in this connection, actually satisfy the above mentioned desire. Flocks of birds, in particular, bulbuls, jays, thrushes, and others of like size are usually seen pecking the seeds of the plants during the period of privation, that is, January and February.