The co-evolutionary relationship between corvid birds and acorn-bearing plant species, through the food hoarding behavior of the former, is well known. However, acorns include chemical defenses, such as tannins, the quantity of which changes during acorn growth. Few studies have attempted to elucidate the utilization pattern of acorns by corvids during the process of acorn ripening. We conducted a study on the acorn foraging behavior of Lidth's Jay Garrulus lidthi, on Amami-Oshima, Kagoshima Prefecture, during the acorn ripening season of 2000–2001. Jays consumed Quercus glauca and Castanopsis sieboldii acorns and utilized many more green acorns than brown ones of both species. The nutrient content did not differ between green and brown acorns or was higher in the former, while the tannin content did not differ in relation to color. This suggests that even green acorns are profitable food resources. While green Q. glauca acorns germinated, green C. sieboldii acorns did not. Consumption of Q. glauca acorns was much higher for C. sieboldii, despite the greater amount of tannin in the former than in the latter.The results of this study suggest that jays are a more effective potential dispersal agent for Q. glauca, than for C. sieboldii.
Bird specimens previously stored in the Tokyo Imperial Household Museum (TIHM) were collected by two National Museums in the Meiji (1868–1912) and Taisho (1912–1926) periods. The collection, now stored at the Yamashina Institute for Ornithology (YIO) cannot be effectively used for research, because the specimen data is unclear. Our aim was to restore the collection data for the specimens. This study was conducted to investigate the collection's history, targeting specimens among the TIHM collection that were derived from the Australian Museum. We discovered, from lists of specimens sent by the Australian Museum, that specimens reached the YIO from two sources. Of the total of 329 bird specimens sent from the Australian Museum, 195 were donated in 1888 to the Tokyo Educational Museum, and 134 were donated in 1893 to the Imperial Museum. In this study we confirmed that 326 (99.1%) of the 329 specimens donated by the Australian Museum in 1888 and 1893 are held by YIO. We will restore collection data using documents discovered during this study enabling us to enhance the scientific value of a large Australian bird specimen collection in Japan.
The main prey of Brown Hawk-Owl Ninox scutulata japonica during the breeding season consists of Coleoptera, although Lepidoptera are also delivered frequently to nestlings during the early nestling period. Changes in the frequency of food items delivered during the nestling period are unclear because Brown Hawk-Owl forage for insects at night. To evaluate how prey abundance in the nesting territory affects changes in the frequency of delivery of Coleoptera and Lepidoptera to nestlings, we collected prey remains around the nest site, and surveyed the amount of insects consumed as the main prey of the Brown Hawk-Owl. In order to be able to discuss the characteristics of feeding ecology, we also investigated the body parts of insects that Brown Hawk-Owls delivered to their nest. Although there were fewer individual Lepidoptera than Coleoptera within the territory of the owls, adult owls frequently delivered Lepidoptera to their chicks until the middle of the nestling period. Brown Hawk-Owls then switched their main prey from Lepidoptera to Coleoptera, according to the abundance of insects within their territory, towards the end of the nestling period. These results suggest that Brown Hawk-Owls selectively delivered Lepidoptera to their nestlings until the middle of the nestling period, but that this selectivity disappeared toward the end of the nestling period. Heads, thoraxes, and abdomens of Lepidoptera, and abdomens of Coleoptera were delivered frequently to nestlings suggesting that Brown Hawk-Owls may select soft exoskeletons of Lepidoptera and Coleoptera due to the undeveloped digestive organs of their chicks. To understand the species-specific feeding ecology of the Brown Hawk-Owl, we should investigate the species' feeding pattern in relation to the development of the digestive organs of the nestlings.
In Japan, metal snow poles are placed beside roads in heavy snowfall regions, indicating the road edges to drivers during winter. Some poles have a hole at the end, and some cavity-nesting birds use these as nesting cavities. During the 2019 breeding season, we investigated how many birds nested in such poles along a road around Lake Onuma, Hokkaido. A total of 218 poles was checked, 89 contained holes and birds certainly nested in 14 poles and may have nested in 10 more. Eurasian Tree Sparrow Passer montanus, Russet Sparrow P. rutilans, and Chestnut-cheeked Starling Agropsar philippensis were observed nesting.