In 1999 we discovered an occupied Goshawk (Accipiter gentilis) nest located in a black pine (Pinus densiflora) forest near to an area scheduled for development. We attempted to ensure the future breeding success of this pair by placing artificial nests near to the occupied nest. Our aim was to encourage the pair to utilize artificial nests located further from the developed area. The artificial nests were 80-90cm in diameter and about 40cm in depth, and were constructed by placing many small branches in the axes of main branches of natural trees. In 2000 and 2001, three and four artificial nests, respectively, were placed in black pine trees, at locations near to the natural nest of the pair. In 2000 the pair of Goshawks utilized one of the artificial nests located 170m from the natural nest, and in 2001 a nest 200m distant from the previous artificial nest was used. Our attempt at encouraging nesting in a safer location was therefore successful.
In the Tokachi Plain, eastern Hokkaido, the population trends of Latham's Snipe Gallinago hardwickii were clarified by comparing census results obtained in transect surveys made in late April to early July 1978-1991 with those in the same season of 2001. The average number of birds counted decreased significantly from 3.5±2.9 (average±SD)in 1978-1991 to 2.7±3.0 in 2001. Among the 38 2-km transects made, between 1978-1991 and 2001 the number of birds recorded decreased in 22 transects (57.9%), increased in 11 (28.9%), and remained the same in five (13.2%). When transects were classified into three types; A=agricultural land in both survey periods, B=agricultural land with woodland (more than 20% of the transect is adjacent to woodland) in both survey periods, and C=agricultural land in 1978-1991 which changed to agricultural land with woodland in 2001, the average numbers of birds decreased significantly in Type A habitat, but remained unchanged in habitat types B and C. Agricultural land with woodland is considered to be a favorable habitat because Latham's Snipe often utilizes isolated woods as a preferred nesting site. The results indicate that during the past 10 to 20 years the numbers of Latham's Snipe have decreased in agricultural land, but have remained basically unchanged in more-suitable habitats. Additionally, results showed that by 2001, 10% of 64 transects in which censuses were conducted in 1978-1991 had changed into habitat unsuitable Latham's Snipe. This suggests an overall decrease in the area of favorable habitat for this species in Hokkaido.
The population trends of the Japanese Night Heron Gorsachius goisagi, the Goshawk Accipiter gentilis and the Grey-faced Buzzard Butastur indicus were estimated based on records of the number of individuals kept in Japanese zoos since the 1960s. Because no special effort is made to collect these species, and because they seldom breed in captivity, their population changes in zoos were assumed to reflect that of the wild populations. In order to reinforce the zoo data, we collected local records of the population trends of these three species in Niigata Prefecture, Tochigi Prefecture, Cape Irago of Aichi Prefecture and the Miyako Islands of Okinawa Prefecture. The results indicated that at all investigated localities, except Tochigi Prefecture, the Japanese Night Heron and the Grey-faced Buzzard had decreased in numbers since the 1960s, whereas the Goshawk had increased in number nationwide. There is, however, a possibility that the increase in the Goshawk population is an overestimation, and it is necessary to investigate its wild population trend in detail. The most likely cause of the declines of the Japanese Night Heron and the Grey-faced Buzzard is habitat degradation, both in quality and in quantity. To date, these two species have not been the targets of any concerted conservation effort, but they must henceforth be accorded this status.
When maintained in captivity in 'intensive aviaries' that offered suboptimal and unnatural living conditions, parent Crested Ibis successfully incubated their eggs but subsequently killed the chicks and discarded them at the point of hatching. In order to investigate this aberrant behavior, new 'semi-natural' breeding cages were established in natural woodland habitat, and the parental behaviors of five breeding pairs from F1 and F2 generations were examined using video recordings. Over the three-year study period, 13 chicks hatched and were successfully raised by the parents in the semi-natural cages, whereas no parental care was provided to those chicks that hatched in the intensive aviaries, and all perished. This experimental evidence revealed that their killing of the chicks might be a consequence of environmental stress caused by their inability to adapt to the artificial environment of an unnatural enclosure. We concluded that the environmental conditions under which they are maintained is a crucial factor for the behavioral adaptation and captive breeding success of this endangered species.
We studied the foraging behavior of the Japanese White-eye in three species of mangroves, Bruguiera gymnorrhiza, Kandelia candel and Rhiziphora mucronata, in July-August and October at sub-tropical Iriomote Island, southern Japan. During the study period the Japanese White-eye appeared to utilize only one species as a nectar source; B. gymnorrhiza, which has flower characteristics specialized for pollination by birds.
The incidence of return to their breeding grounds by the Reed Bunting Emberiza schoeniclus was investigated in western Hokkaido during six seasons (1997-2002). During this survey period, a total of 1, 568 individuals (508 adults, 411 juveniles and 639 nestlings) were given leg bands in the breeding season (Apr. 1-Sept. 10). A total of 150 birds were recaptured after one year, indicating the estimated minimum return rate in the next year as being 9.57%. The return rate dropped exponentially over subsequent years, falling to 1% or less 4-5 years later. The rate of return after one year in adult birds, juveniles and nestlings was 14.37%, 10.22% and 5.48%, respectively. There was no difference in the rate of return between adult males and females. It is conceivable that the true return rate may be higher than our estimates, because not all the returned individuals were necessarily captured by the end of this survey period.
In 2002, young Japanese Cranes Grus japonensis held captive in a facility located next to the winter feeding station in Hokkaido showed symptoms of Disseminated Visceral Coccidiosis (DVC). Screening revealed the presence of oocysts of the coccidia Eimeria gruis and Eimeria reichenowi in the feces of wild cranes, the first record of this infection in wild cranes in Hokkaido. Coccidian oocysts were distributed throughout the entire habitat area, though no serious effects have yet occurred. Given the high density of cranes at winter feeding stations and the decrease of the breeding habitat in Japan, the potential danger posed to the natural crane population by eimerian coccidiosis should be an important concern in the wildlife management practices for this species.
We observed that two species of crows reused nest materials. Given the conventional knowledge that crows avoid breeding in their old nests, this behavior is both novel and surprizing. Pairs removed materials from their completed nests and carried them to other sites, and there used the old materials in the construction of new nests. It is unknown whether any eggs were laid in the original nest or whether the nest was abandoned prematurely. One pair of Carrion Crows reused twigs, and two pairs of Jungle Crows reused wire-hangers and twigs for the outer shell of their nests. However, inner linings were newly obtained in all cases. These observations suggest that the reuse of nest materials by crows may be more common than was hitherto believed.