In Hokkaido most bird species (e.g., Black-faced Bunting Emberiza spodocephala, Carrion Crow Corvus corone, Large-billed Crow C. macrorhynchos, and Japanese Tit Parus minor) are distributed throughout all districts of the prefecture during the breeding season. Some species are more commonly distributed in southern (Lesser Cuckoo Cuculus poliocephalus and Barn Swallow Hirundo rustica), south-western (e.g., Honey Buzzard Pernis ptilorhynchus, Japanese Thrush Turdus cardis, and Japanese White-eye Zesterops japonicus), eastern (Lesser Spotted Woodpecker Dendrocopos minor), north-eastern (Common Merganser Mergus merganser) or northern areas (Yellow Wagtail Motacilla flava). A few species (e.g., Black-browed Reed Warbler Acrocephalus bistrigiceps) have a different distribution pattern and found in coastal areas and along the middle and lower reaches of rivers. Grassland birds (e.g., Eurasian Skylark Alauda arvensis and Chestnut-eared Bunting Emberiza fucata) occur mainly on plains and in basins with grasslands. In contrast, forest birds (e.g., Hazel Grouse Tetastes bonasia and Japanese Robin Luscinia akahige) except those species occurring also in agricultural lands, are distributed mainly in mountainous forest-covered areas. The range of birds occurring at high elevation (Red-flanked Bluetail Tarsiger cyanurus) are narrower than those of birds occurring from low to high elevation. The abundance of species occurring in south-western areas (Japanese Thrush) increases in line with rising air temperature. Conversely, the abundance of species (Common Merganser) increases as the air temperatures decline. The abundance of birds occurring in high elevation (Red-flanked Bluetail) increases as the altitude increases. These facts suggest that air temperature is one important factor determining the distribution of some species. The number of species with a south-western type distribution is greater than that of species with a north-eastern type. This is considered to be because of the greater similarity between the avifaunas of Hokkaido and Honshu than between those of Hokkaido and Sakhalin or Primorye.

During a study of the nesting habitats of the Jungle Nightjar Caprimulgus indicus in central Okayama Prefecture, Japan, a total of 119 potential territories were surveyed in 2015–2020. Sixteen nests were confirmed, five with nest traces (neither parents nor chicks were seen), five with eggs but no chicks, and six with eggs and then chicks. Nesting habitat preferences included open areas with dry and sparsely bushed ground, near ridges covered with Japanese Red Pine forest and secondary coniferous plantations. Although usually found on hillsides, nest sites were typically on relatively flat ground compared with the immediate surroundings.

Compared with the USA and UK, fewer people in Japan feed wild birds in their gardens. One explanation for this difference is that the number of birdwatchers in Japan is small and therefore the number of people feeding wild birds is also small. Another explanation is that there is generally little interest in feeding wild birds in Japan. To see which of these explanations might be correct, or whether both are correct, firstly, we examined the membership of birdwatching organizations as an indicator of the number of birdwatchers in each of the three countries. Both the absolute number and the number relative to the population was by far the lowest in Japan. Secondly, in order to compare the intensity of interest in birdwatching and in bird feeding among the three countries, we compared the number of reviews and prices of products related to birdwatching and bird feeding on the Amazon e-commerce sites in each of the three countries. In the USA and the UK, there were more reviews for wild bird feeding products than for birdwatching products, whereas in Japan there were more reviews for birdwatching products. The average price of birdwatching products was higher than that for feeding in all three countries, but the difference was greatest in Japan, indicating that respondents spent more on birdwatching than on feeding birds. These findings suggest that the feeding birds in Japan is not widespread due to the small number of birdwatchers, and their lower interest in feeding birds, than in the other two countries.

Damage to lotus root crops by ducks and coots is reported about 300 million yen in fiscal 2020 in Ibaraki Prefecture, where the top producer of lotus roots in Japan. Lotus roots are grown in the mud of flooded fields, and farmers have claimed "duck damages" because they have found partly hollowed lotus roots when harvesting. However, there was no previous conclusive evidence confirming that waterfowl forage on the roots. To determine which species cause damage and how they eat the roots, we placed lotus roots in a post-harvest lotus field, where the average mud surface was 20 cm below the water surface, and monitored nocturnal avian behavior during 16 trials from February to March 2021. For each trial, we placed fresh lotus roots with two to four nodes at different depths in the lotus field (from the water surface to 52 cm below the surface) or on the levee before sunset. Avian behavior was monitored overnight by automatic infra-red cameras. Eurasian Coots Fulica atra and Mallards Anas platyrhynchos frequently visited and started to eat lotus roots placed on the levee or at the water surface by pecking. Then, for lotus roots down to 20 cm below the surface, they dipped, submerged the head and neck to reach food. Finally, for deeper roots (20 to 40 cm below the surface) some up-ended and some dived (Eurasian Coots) or they stirred the mud with their feet (Mallards). By the morning, bowl shape hollows had been made in the mud surface 20 to 42 cm below the water surface, and the lotus roots only remained 40 cm or deeper beneath the surface. Small numbers of other waterfowl species also visit the lotus fields. Falcated Ducks A. falcata ate lotus roots on the mud surface; Eurasian Wigeons A. penelope ate them on the levee and at the water surface, whereas Northern Shovelers A. clypeata, Common Teals A. crecca, and Gadwalls A. strepera did not eat them. Mallards and Eurasian Coots, at least, were confirmed to be capable of causing damage to commercially valuable lotus roots, especially in shallow water.

We investigated the genetic relationship between parents and broods of the Japanese Tit Parus minor in a residential area in Saitama Prefecture from 2011 to 2014. We obtained blood samples, and extracted DNA, from nine adults and 36 nestlings in five nest boxes. We conducted microsatellite polymorphism analyses using 12 markers. The EPP ratio, estimated from genetic polymorphism of the nine valid markers, was 3.0 or 6.1% (one or two out of 33 nestlings). Some nestlings shared no genetic relationship with either of their parents, indicating that intraspecific brood parasitism or nest take-over had occurred.

Carrion Crows Corvus corone drop Manchurian Walnuts Juglans mandshurica onto the ground or allow cars to run over them in order to break them open for consumption. Shell toughness or fragility of walnuts may be an important factor in the choice of strategies. In this study of seasonal differences in the toughness of walnut shells, we dropped walnuts from a high position in both October and December and found that they were more easily broken in December than in October.

With human population growth occurring in urban areas, there is a concern that human-induced disturbances have adverse effects on urban-dwelling raptors. Here, we surveyed the rate of successful reproduction of urban-dwelling Northern Goshawks Accipiter gentilis in Tokyo, Japan for two years and compared the rate between occupied nests inside and outside protected areas. Occupied nests inside protected areas were almost three times more successful than those outside protected areas (63.6% vs. 21.4%), indicating that urban-dwelling goshawks are not always tolerant of anthropogenic disturbance. Therefore, it is important to limit human activity near their nest sites.

A mass mortality event involving 13 Red-necked Phalarope Phalaropus lobatus occurred in a suburb of Iwamizawa, Hokkaido, northern Japan, in September, 2010. Gross postmorterm examinations revealed that they were in good condition with healthy levels of subcutaneous fat, but they had sustained injuries suggesting that they died from a fatal collision.

A search for Japanese Marsh Warblers Locustella pryeri was conducted at 86 wet-grassland areas in Kyushu Island, southern Japan, in the winter of 2021–2022, found 16 individuals at seven sites. Wintering sites were found in two regions, along the Japan Sea coast of northern Kyushu and on the Satsuma Peninsula. Abandoned rice fields were the most important habitats. Almost all warblers were found in wet-grasslands with common reeds less than approximately 2 m in height and with abundant understory.