We captured a female individual of Middendorff's Grasshopper Warbler Helopsaltes ochotensis with a plumage colour aberration in July 2024 along Ishikari River in Hokkaido, Japan. Although it showed almost normal plumage colour as a whole, some of its feathers such as primaries, secondaries and rectrices were unnaturally whitened. Based on the position of those abnormal white feathers, we concluded that the colour aberration of this individual should be classified as ｀leucism’. This is the first report of a leucistic individual in the Locustellidae.

The behaviour of a pair of Spectacled Guillemots Cepphus carbo in a nest was recorded by a small 4K camera during four breeding seasons. Parents started to visit the nest in mid-April to mid-May, and laid eggs in mid-May, 2 – 9 days after copulation in the nest. Long (> 3 days) absence from the nest before egg-laying, i.e. exodus, was not observed. Clutch size was two in 2019 and 2020 and one in 2021 and 2022. Chicks were hatched after an incubation period of 28 – 31 days; two chicks fledged in 2019 and one in 2020 and 2022 at 35 – 46 day- age, but not in 2021 because two other birds took over the nest in mid-Jun. Males visited the nest more often than females during the pre-laying period but the time in the nest, the time for incubation and the frequency of feeds were similar. Parents brought mainly sand lance Ammodytes spp. in 2019 (85% in number) and 2020 (95%), but its proportion decreased in 2021 (58%), and they brought demersal fish only in 2022. No apparent sex differences in the prey species provided were observed. High-quality images collected by a small camera set in the nest help studies of behaviour of the burrow/crevice nesting seabirds during the pre-laying period.

The Great Crested Grebe Podiceps cristatus is a winter visitor in many parts of Japan. This species is known to breed in Hokkaido and a few areas of northern and central Honshu, and has recently expanded its breeding range. However, there have been no reports on breeding in Nagano Prefecture. Here, I report the first breeding record of the Great Crested Grebe in the prefecture, observed at Lake Suwa, central Nagano, from June to August 2024. On 7 August 2024, six chicks were observed along with a breeding pair.

The external morphology and DNA of a Phylloscopus specimen found in Fukui Prefecture in January 2021 were examined, and it was identified as a Kamchatka Leaf Warbler Phylloscopus examinandus. This is the first record of this species (considered a transient visitor in Japan except for the Shiretoko Peninsula) in Japan in winter.

Line censuses have been undertaken at the Imperial Palace, Tokyo, to reveal the avifauna, since 1965. Here we report results of the line census from April 1976 to March 1996. The line census was conducted on a route of 4.1 km between 9:00 – 12:00, in the same way as the census conducted continuously before and after this study. We divided the study period into the early one from April 1976 to March 1986 and the late one from April 1986 to March 1996, and compared the two study periods. We observed 23,190 individuals of 76 species in the early study period (68 censuses) and 29,887 individuals of 72 species in the late study period (95 censuses; 89 species through the whole study period). Comparing 14 species with the higher relative frequency in 10-year-period before the early study period, and the 4-year-period after the late study period as well as the two study periods, Aix galericulata, Anas zonorhyncha, Streptopelia orientalis, Nycticorax nycticorax, and Spodiopsar cineraceus seemed to decrease, while Yungipicus kizuki, Sittiparus varius, Parus cinereus, Hypsipetes amaurotis, Zosterops japonicus, and Emberiza personata seemed to increase. Among these species, Aix galericulata, Anas zonorhyncha, Streptopelia orientalis, Nycticorax nycticorax, Yungipicus kizuki, Parus cinereus, Zosterops japonicus, Spodiopsar cineraceus, and Emberiza personata fluctuated significantly between the early and late study periods. Five and six species without the higher relative frequency also significantly decreased and increased, respectively. For Nycticorax nycticorax, Cyanopica cyanus, Zosterops japonicus, and Spodiopsar cineraceus, in which the numbers observed changed significantly between the two study periods, the changes seemed related to seasonal change. Conversely, the other species in which the observed number changed significantly, did not seem to change seasonally but to increase or decrease through a year. From December to March, ca. 25 species were observed. Twenty seven and twenty five species were observed in April in the early and late study periods, respectively; thereafter the number of species declined and reached a minimum of 17 and 15 species in August, the early and late study periods, respectively, and then switched to an increase during September and November. In November, the number of species reached 23 and 26, respectively. However, the number of species did not differ significantly in any month between the two periods.

We investigated whether forest-dwelling birds hunt small mammals nesting in tree cavities. Camera traps were installed in front of the tree cavities where flying squirrels (Pteromys momonga and P. volans) were nesting from December 2017 to November 2019 on Honshu Island, and from September 2021 to April 2022 on Hokkaido Island, Japan. These cameras also observed the behavior of the visiting predators. As a result, a Crow Corvus sp. and a Ural Owl Strix uralenesis hunted P. momonga and P. volans, respectively. Both birds hunted in the outer and inner shallow parts of tree cavities. These observations provide information to help understand the diversity of hunting sites for forest-dwelling birds.