We studied the breeding ecology of Eastern Crowned Leaf Warbler Phylloscopus coronatus and brood parasitism by the Oriental Cuckoo Cuculus optatus in western Hokkaido for 17 years. Of 135 nests found, most were on the ground (65.2%), or on the collapsed stems and leaves of bamboo grass (32.6%). The average clutch size of 6.4, was larger than that found in previous studies, perhaps because of the latitude of the study site. The average incubation period was 11.7 days and the average nestling period was 10.9 days. Both male and female warblers contributed to feeding their nestlings, but the parental division of labor varied greatly among nests and over time; the average feeding ratio of females was higher in the later (45.5%) nestling period than in the earlier (34.8%) nestling period. The probability of survival from the start of incubation to fledging, as calculated using the Mayfield method, was 0.411 (0.781 for the incubation period and 0.526 for the nestling period). Predation of warblers was significantly higher (33.6%) during the nestling period than during the incubation period (13.0%). The average rate of brood parasitism by the Oriental Cuckoo was 16.3% throughout the study, but varied from a high of 37.5% to a low of 0.0% over the 11 years from 2012 onwards. All Oriental Cuckoo eggs were plain reddish-brown, and though strongly contrasting with the white eggs of East Crowned Leaf Warblers, the warblers did not reject either cuckoo eggs or nestlings . The average incubation period of the cuckoo eggs was 11.5 days, the nestling period was 16.3 days, and the fledging success rate was 36.4%.

In Obata Ryokuchi Park, Nagoya City, mixed-species flocks typically include five species: Japanese White-eye Zosterops japonicus, Long-tailed Tit Aegithalos caudatus, Japanese Tit Parus minor, Varied Tit Poecile varius, and Japanese Pygmy Woodpecker Dendrocopos kizuki. While there have been many studies of Long-tailed Tit in heterospecific flocks, there have been few studies of Japanese White-eye, and their role (as flock leaders or flock followers) is not known. We aimed to elucidate Japanese White-eye's role in heterospecific flocks by examining flock structure, changes in behavioral allocation, and responses to playback experiments using the calls of the five species that compose the flocks. Two types of mixed-species flocks were observed at the study site, one consisting mainly of Long-tailed Tit, and one consisting mainly of Japanese White-eye. When in heterospecific flocks, Japanese White-eye reduced their time spent in vigilance behaviour. In playback experiments, Long-tailed Tit was only attracted to calls of conspecifics, whereas Japanese White-eye and the three other species were attracted to calls of Long-tailed Tit. Accordingly, we have revealed that Japanese White-eye behaved as a passive nuclear species in heterospecific flocks not including Long-tailed Tit, but otherwise acted as an active nuclear species.

In order to reveal the home range and habitat selection of the endangered Brant Goose, wintering in Shizugawa Bay, a Ramsar site in Miyagi Prefecture, we attached GPS loggers to seven individuals and tracked them during two consecutive wintering seasons (2019–2020 and 2020–2021). Home range and habitat selection during daytime and at night were determined using the fixed kernel method and GIS analysis. The averages of 95% and 50% kernel home ranges were 3,316.3 ha and 518.7 ha respectively during daytime, and 9,480.1 ha and 1,965.5 ha at night. The areas of the home ranges used at night were similar to those used in daytime. With the exception of one individual that was strongly dependent on fishery harbors, the 95% and 50% kernel home ranges during daytime included fishing harbor areas, fishery raft areas and eelgrass beds, which was consistent with the results of previous visual observations. The geese foraged for seaweed in fishery harbors and around fishery rafts, that were widely distributed in the bay, while eelgrass beds, that have high energy value as food, were locally distributed. In addition, the geese were limited in their access to eelgrass beds because of deep water in the area of the eelgrass beds. Therefore, the geese foraged for shredded eelgrass that floated to the surface or acquired it by kleptoparasitism of Eurasian Coot. While maintaining fishery harbors and fishery rafts, eelgrass beds are an important habitat for the conservation of the endangered Brant Goose, one of the symbolic species occurring in Shizugawa Bay.

Records of Baikal Teal (Anas formosa) flocks involving tens of thousands of individuals are rare in Japan, thus little research has been done to determine where and how these large flocks spend their time. In February 2020, more than 20,000 Baikal Teals were found at Lake Shinji in Japan. The aim of this study was to observe and assess their flight behavior and feeding area during winter. Flocks were seen to fly from the lake twice a day, in the morning and in the early evening. Continuous investigation of their destination revealed that they landed on a wooded hillside near the middle reaches of the Hii River. Some of the woodlands included acorn-bearing Oak trees (Quercus spp.). Images from a camera trap placed in the woodland indicated that Baikal Teals were feeding on these acorns.

A survey of wintering Japanese Marsh Warblers Locustella pryeri was conducted at 107 wet-grasslands in the Chugoku and Shikoku regions of western Japan during the winter of 2022–2023. Ten individuals were widely found at five sites. Abandoned rice fields were the most important wintering habitats. Almost all warblers were found in wet-grasslands with Common Reed Phragmites australis less than approximately 2 m in height and with abundant understory.

Geese, swans and ducks (Anatidae) are thought to avoid the sound of UAV rotor blades. In this study we measured the reactions of flocks of Anatidae to prerecorded UAV rotor sounds. The sound levels heard by Anatidae flocks were estimated using distance attenuation models of UAV rotor sounds. Our results indicated that rotor sounds below about 50 dB were not a primary avoidance factor, whereas avoidance behavior was triggered mainly by the visual impact of the UAV. However, if rotor sounds are louder than 50 dB, they may trigger avoidance by Anatidae.