The breeding season of the Grey Starling Sturnus cineraceus is divided into two periods: the early and late breeding periods. The birds that breed in each season are referred as to early and late breeders, respectively. In the early breeding population, about half of all breeders were early breeders from the previous year and most of the rest were early immigrants breeding for the first time in the study area. However, the late breeding population consisted mainly of late immigrants which had not bred in the early season, with early breeders having a repeated or a second brood making up only one third of the population. The higher reproductive success seen in the early season suggests this period to be more favorable for breeding than the late season. Intraspecific brood parasitism occurs in this species. The mean number of parasitic eggs per nest and parasitic rate were high in the early season. In each year, competition for nesting boxes was severe, and this competition may exclude the surplus birds from breeding. As a result, many surplus birds probably become intraspecific brood parasites (Saitou 2001). There was also a positive correlation between parasitic rates in the early season and the number of late immigrants, suggesting that many surplus birds in the early season probably become part of the late breeders. The mean annual disappearance rate of late immigrants was significantly higher than that of early breeders, and seemed to result partly from the emigration of late immigrants. In the early season, the proportion of early immigrants was always higher than that of the late breeders becoming early breeders the following year. However, on average, only about one fifth of late immigrants became early breeders. The high disappearance rate and low proportion of late immigrants becoming early breeders suggest that the late immigrants consist of both resident and nomadic types.
Some ducks foraging on land regularly alternate their behaviors between feeding and bill-dipping into the water. I observed activities during foraging, including this switching, in captive White-faced Whistling Ducks, Dendrocygna viduata, under two conditions in which the distance between the water and food is different (sample images are available at the MOMO Video Archive web site, http://www.momo-p.com with the data no.: momo010929dv01b and momo010929dv02b). When the distance became greater, the total time spent feeding on grain, feeding on bread, bill-dipping, and the total of other behaviors, did not change, whereas the frequency of feeding on grain and bill-dipping decreased, and that of preening, increased with greater distance. Bout duration of feeding on grain and bill-dipping also increased when the distance became further. The increase of bout duration of feeding on grain was significantly longer than expected, while that of bill-dipping did not differ from expected. Considering the preening can be a displacement activity, the increase of bout duration of feeding could be caused by competition for feeding sites rather than optimal adjustment predicted by optimal central place foraging.
The subspecies fujiyamae of Northern Goshawk Accipiter gentilis breeds in Japan, Sakhalin, and Southern Kurile Islands as an endemic subspecies (OSJ 2000). This paper shows the measurements from 64 individuals of A. g. fujiyamae caught in central Saitama and southeastern Tochigi Prefectures, Honshu, along with the identification criteria of sex and age based upon measurements (Table 1), plumage features (Fig.1), and iris colour (Table 2). Adult males were significantly smaller than adult females for all measurements (Table 1). Tails of juveniles were significantly longer than adult tails for males (t-test, t=2.238, df=26, P<0.05) and probably also for females (Table 1). We could distinguish the age as juvenile, first winter, and adult plumages based on the plumages combined with iris colour (Fig.1). A few juvenile feathers of upper and under wing-coverts remained in first winter plumage until about two years old, which was the bird's third year. Measurements from live birds tended to be larger than the data reported in the literature, which were mostly taken from specimens. The difference was as large as 10 mm in the case of tarsus length. The iris was pale yellow (sulfur yellow) in juvenile plumage and tended to acquire an orange tinge as the bird aged, mainly spectrum yellow or orange yellow in first winter plumage, and orange yellow or orange in adult plumage after in the second winter plumage. We show for the first time that the iris may turn red for old males of Japanese Northern Goshawks A. g. fujiyamae (Table 2 and Fig. 1).
This paper reports the results of an experiment for testing the applicability of a Wireless Fidelity (WiFi) positioning system to tracking free-range chickens. In this system, the location of a chicken on a continuous plane (an experiment field) at any time was represented by a point (referred to as a location point) on a one meter square grid lattice, and the trajectory of a chicken by the sequence of its location points. The system recorded the location point of a chicken at every second. The experiment used eight Domestic Fowl (Gallus gallus domesticus) and two Helmeted Guineafowl (Numida meleagris galeata), which were kept freely in a park (170 by 90 m), where their spatial behavior was observed for five days. The complete data were collected for three days. Because the observed location points contained random noise, they were treated as probabilistic variables. Data analysis showed that location accuracy was 2.6 m with a probability of 0.95. The living space of a chicken was represented by a two-dimensional probability density function of location points. The function was estimated by the kernel method with the bi-weight kernel function whose bandwidth was 2.6 m. The trajectory of a chicken was estimated by the moving average method. This experiment showed that the WiFi positioning system was practically applicable to tracking free-range chickens.
The distribution and population size of crows inhabiting the alpine zone (above 2,400 m asl), central Honshu, were studied on the basis of published literature, a 2005 questionnaire survey and interviews of the owners of mountain huts. Crows were present at 45 of the 62 high mountains surveyed. The distribution was increased because the crows occurred at 11 mountains before the 1970s. There were 1-4 individuals at each mountain and they were usually observed from May to October when the mountain huts opened. We estimated a total of 156 individuals at the 45 high mountains: most were Jungle Crows (Corvus macrorhynchos). The crows scavenged the food scraps dumped by mountain climbers. Moreover, at some mountains they ate the eggs and chicks of the Rock Ptarmigan (Lagopus mutus), the Alpine Accentor (Prunella collaris), and the House Martin (Delichon urbica). Attention should be paid to the future distribution and diet of crows inhabiting the alpine zone.
High concentrations of insecticide “fenthion” were detected in the muscles, livers and stomach contents of several dead Japanese Cranes (Grus japonensis) found at Memambetsu Town, northeastern Hokkaido. A follow-up survey in another five dead cranes revealed high fenthion concentrations in the pectoral muscle, liver and stomach contents of two cranes found at Shibecha Town and Tsurui Village in eastern Hokkaido. The concentrations of fenthion were 0.14 mg/kg-wet in muscle, 0.13 mg/kg-wet each in liver and 7.9 mg in stomach contents, respectively.