There is little information on the population status or distribution of Swinhoe's Rail Coturnicops exquisitus in Japan. An effective survey method has not yet been established, and this contributes to the lack of knowledge about the species' ecology and distribution in Japan. We conducted a multi-year and multi-season survey using call playback to determine its population status in Ibaraki Prefecture, on the northeast coast of Japan. We conducted call playback method at 14 points within 12 areas, including a seemingly suitable habitat dominated by Carex spp., a short herbaceous plant, mixed with Phragmites spp., a tall herbaceous plant, in Ibaraki Prefecture from January 2016 to May 2018. The species was identified by analyzing spectrogram of the recorded calls, and by characteristic features of the birds flight from the call locations. We confirmed the species present at nine points within seven areas, and we recorded at least two individuals at five points within four of those areas. Based on those results we estimated that the population in the one of the areas was between 8 and 15 rails/ha in three winters. In a year-round survey, the rails were recorded from early November to middle or late April. These results indicate that Swinhoe's Rails regularly overwinter in Ibaraki Prefecture.

We tracked 16 Mallards Anas platyrhynchos and 2 Spot-billed Ducks A. zonorhyncha wintering around Lake Izunuma-Uchinuma, northern Japan, by using GPS-TX in 2017/18 and 2018/19 to determine their habitat use through day and night. Mallards showed diurnal resting and nocturnal activity patterns. The nocturnal foraging patterns of both eight male and eight female Mallards varied among individuals, and some of them stayed in the lake while other ducks were distributed in lotus fields, flooded paddy fields, pond and a river north of the lake. Spot-billed Ducks also showed diurnal resting and nocturnal activity patterns. They were distributed in narrow-width irrigation canals, lotus fields, and flooded paddy fields north of the lake. The two species demonstrated some overlap site use, but Mallards did not use narrow irrigation canals. Use of GPS-TX was a powerful method to track waterfowl in the local landscape, and hereafter we intend to investigate the two species' wintering ecology.

We monitored a nest of Northern Goshawk Accipiter gentilis to investigate the cause of continuous nestling loss in an isolated forest patch of Ichinoya Forest in Nagareyama City, Chiba Prefecture, eastern Japan. Using a closed-circuit television (CCTV) camera and digital video recording system, to limit potential disturbance to a minimum for the nesting birds, we monitored the nest during the breeding season of 2018. The result revealed that one of the two nestlings that survived in 2018 was predated by a Japanese Rat Snake in the nest during the night of 26 May, 2018. Although the nest tree was safe-guarded against climbing animals such as Masked musangs Paguma larvata (masked palm civet) or Raccoons Procyon lotor using an ironbelt, the snake approached the Goshawk nest using branches of an adjacent Japanese cedar tree. For a better conservation results, in areas where a deft climber such as the Japanese Rat Snake occurs, we recommend to restrict access to nest trees by managing the adjacent vegetation as well as with trunk protection for the nest tree itself.

Wing-spreading behavior by Japanese Paradise Flycatcher Terpsiphone atrocaudata was observed 15 times among 12 breeding pairs in Iwate Prefecture northern Japan during 2013-2019. This behavioral display was observed from parent birds with fledglings nearby as the observer approached them during, before, and after the nestling fledged. It is possibly a threatening display against the intruder to protect the young.

Sika Deer Cervus nippon has been increasing in many forested areas of Japan during the prior 20 years, and it is known that the abundance of birds that use the forest understory has been decreasing in those areas. Since some of those birds are hosts to brood-parasitic cuckoo species, we analyzed monitoring data to look for a related decrease of those brood-parasitic species. The data used for the analysis were the Japanese Ministry of the Environment's “Monitoring Site 1000,” which are bird survey data collected at 20 sites from 2010 to 2019. In the areas with no or light deer browsing, there was no significant decrease in the abundances of Bush Warbler Cettia diphone, Sakhalin Leaf-warbler Phylloscopus borealoides and Eastern Crowned-warbler P. coronatus, all of which use the forest understory. The abundances of Lesser Cuckoo Cuculus poliocephalus and Himalayan Cuckoo C. optatus, brood parasites of the birds that inhabit the forest understory, did not show a particular decrease. There was a significant decline, however, in the abundances of these species in areas with heavy browsing by deer. For brood parasites, the host is an indispensable breeding resource, and the effect of the deer browsing impacts the cuckoos through the decrease of the host population.

This data set is aimed at monitoring the effects of climate change on the timing of breeding by forest birds (Fig.1). The data were collected in the forests of Teshio (Hokkaido Pref.), Ashoro (Hokkaido Pref.), Tomakomai (Hokkaido Pref.), Kayanodaira (Nagano Pref.), Ooyamazawa (Saitama Pref.) and Ichinomata (Kochi Pref.) by using Integrated Circuit (IC) recorders between April to May, 2009-2019 (Table 1). We listened to the recorded sounds to identify bird species and sound type (e.g. song, drumming, or call). We collected the data in two minute-intervals during two periods each morning. The first period was from six minutes before sunrise to four minutes after sunrise, and the second period was from 50 minutes to 60 minutes after sunrise.

We expect that this data set will provide useful basic information for various types of bird studies.

Data download:

http://www.bird-research.jp/appendix/br15/15r01.html