[in Japanese]

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Birds breeding in forests have been monitored by point count methods at 21 sites throughout Japan between 2003 and 2009. We analyzed the population trends of 25 species that were recorded at more than 10 survey sites. Population indices and long-term trends of each species were calculated using TRIM (TRends and Indices for Monitoring data). Bush Warblers Cettia diphone and Siberian Blue Robins Luscinia cyane showed significant declines, while Narcissus Flycatchers Ficedula narcissina showed a significant increase. Twenty-two other species of bird showed no significant changes in populations. Bush Warblers and Siberian Blue Robins use the forest understory for foraging and breeding. Data from other studies have shown that the forest understory has decreased at many sites in Japan due to the impact of browsing by Sika Deer Cervus nippon (Saeki 2013). When the bird monitoring data was evaluated in conjunction with the degree of browsing impacts by deer, the abundance of the two bird species tended to be lower in the sites with heavy deer browsing. These results suggested that populations of Bush Warblers and Siberian Blue Robins decreased in part due to the impact of increased deer browsing. Those bird species were also decreasing in the sites with light deer browsing, suggesting that further studies are needed to understand the full range of mechanisms involved in their decrease.

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Since 1990, the Kochi Branch of the Wild Bird Society of Japan has hosted a regular monthly birding event in western Japan at the Kochi Castle Park in Kochi City. We analyzed the birding event’s data from 1990 to 2010, and calculated the occurrence rate (the simple positive or negative observation per survey) and abundance (number of individuals observed per survey) for each bird species observed. Eighty-five bird species were recorded in the last 20 years. The results showed that Bull-headed Shrikes Lanius bucephalus had decreased during that period. Black Kites Milvus migrans and Tree Sparrows Passer montanus appeared to have decreased in abundance even though their occurrence rates did not decrease during this term. On the other hand, Varied Tits Poecile varius had increased in both occurrence rate and abundance. In the case of Large-billed Crows Corvus macrorhynchos and Daurian Redstarts Phoenicurus auroreus, the abundance had increased during this term though their occurrence rates had not changed. The result suggested that monitoring programs for population trends need to include not only occurrence rate, but also another metric, such as abundance, because the trends of one measurement do not necessarily fluctuate in accordance with the other.

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In order to identify the phenological responses of birds to climate change, I have been using small temperature loggers in nest boxes to monitor the temperature conditions during phases of breeding phenology of Varied Tits Poecile varius at the University of Tokyo’s Chichibu Forest since 2010. Until 2014, 6-9 nest boxes were used by Varied Tits each year at the forest. The fledging dates of Varied Tits were not correlated to the temperature of the laying period, but were significantly correlated to the effective accumulated temperature of the breeding season until the laying period. The effective accumulated temperature is known to correlate with the phenology of plants and insects, so these results suggest that Varied Tits may adjust their breeding period according to the phenology of plants and insects. We need further monitoring to confirm if Varied Tits are adapting to the rapidly changing climatic conditions.

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A census of the Red-billed Leiothrix Leiothrix lutea population was conducted in the breeding season of 2014 on the northern slope of Mt. Fuji. Compared to the results of a similar study in 2009, the abundance of this species had decreased significantly, and distribution was reduced. It was thought that the population decline and the change of distribution of the Red-billed Leiothrix was brought about by the decrease of the species’ preferred habitat, the Sasamorpha borealis, due to excessive browsing by Sika deer Cervus nippon. However, populations of the Japanese Bush Warbler Cettia diphone and the Siberian Blue Robin Luscinia cyane that live in similar habitat showed no significant differences in 2014 when compared to the results of a survey in 2012.

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This data set was developed to aid in monitoring the effects of climate change on birds. In 2005, this monitoring of bird phenology began with the cooperation of citizen researchers who reported their observation data to the Japan Bird Research Association via the internet. Citizen researchers reported records of the arrival of specific summer and winter visitors, and of the dates that singing by resident bird species was detected. The species selected for monitoring were chosen for reliability of detection and identification: Eastern Spot-billed Duck Anas zonorhyncha, Lesser Cuckoo Cuculus poliocephalus, Common Cuckoo C. canorus, Brown Hawk-Owl Ninox scutulata, Bull-headed Shrike Lanius bucephalus, Eurasian Skylark Alauda arvensis, Barn Swallow Hirundo rustica, Brown-eared Bulbul Hypsipetes amaurotis, Japanese Bush Warbler Cettia diphone, Japanese White-eye Zosterops japonicus, Oriental Reed Warbler Acrocephalus orientalis, Naumann's Thrush Turdus naumanni and Daurian Redstart Phoenicurus auroreus. We expect that this data set will provide useful basic information for various bird studies. Several descriptive analyses to demonstrate variation in the annual pattern of arrival among years and geography were presented in Figures 1-2 and Electronic Appendices 1-8.
Data download: http://www.bird-research.jp/appendix/br10/10f01.html

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An understanding of the infectious avian disease agents that are present in Japan is an essential tool for conservation. Based on published literature and our own work, this review provides a list and general discussion of the recorded infectious diseases and/or agents (e. g., virus, bacteria, fungi and protozoa) that have affected wild birds in Japan. Potential strategies to reduce risks during outbreaks are briefly outlined and discussed.

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To identify the feeding preference of waterfowl wintering in a freshwater wetland, we conducted experiments both in the laboratory and in the field. In the laboratory experiment, we fed the stems, leaves and tubers of the waterweed Hydrilla verticillata to a Spot-billed Duck Anas zonorhyncha that was wild-caught using a mist net at Hayasaki near Lake Biwa. The captive duck was fasted for 12 hours, then the feeding test presented the two parts of the plant at the same time, but on separate trays, and the duck clearly preferred tubers. In the field experiment, we selected sites with two water depths. The shallow site had a water depth of 30 cm, and the deep site’s water depth was 60 cm. Both sites were vegetated with the H. verticillata community, and were located near the estuary of the Echi River (Echigawa) between the Echigawa Bridge and the Kurimi Bridge (Fig. 1). For examination of tuber density, we established eight survey quadrats. Four quadrats were placed in shallow water and four in deeper water. Each water depth had two bird-exclusion quadrats (covered with nets) and two controls (uncovered with nets). We measured tuber density before and after the arrival of wintering waterfowl, and found that tuber density was significantly higher in the deeper water site than in the shallower water site prior to the arrival of waterfowl, and that foraging by wintering waterfowl significantly reduced the density of tubers at the deeper site (Fig. 3). Thus, we concluded that the waterfowl wintering at the study sites preferred H. verticillata tubers over the leaves and stems, and selected foraging sites based on tuber density.

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To determine the growth patterns of Oriental Dollarbird Eurystomus orientalis nestlings raised in nest boxes in Tottori Prefecture, southwestern Japan, we measured the body weight and tail feather length during nesting seasons from 2008 to 2012. The results showed that nestling increased the body weight to about 160g, but that weight descreased when final weight was about 120g.

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I observed foraging behavior of waterfowl at a pond overgrown with fanwort (Cabomba caroliniana), a non-native aquatic plant. I made observations at Shimizu Pond, located in Mito-City, Ibaraki Prefecture, Central Japan, during April 2011 through March 2012. Bewick’s Swans, Whooper Swans, Gadwalls, Falcated Ducks, Eurasian Wigeons, Mallards, and Coots foraged actively in the bed of fanwort. I observed that the birds mainly foraged stems and leaves of fanwort in winter, but that some species of duck did not appear to consume fanwort.

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Gastric contents of 16 individual Crested Serpent Eagles Spilornis cheela were investigated. The birds were collected between 2000 and 2010 from both Iriomote and Ishigaki Islands, Yaeyama Archipelago, Okinawa, Japan. From 11 of 14 stomachs, a total of 13 types of stomach contents were identified, including crabs, earthworms, locusts, cicadas, frogs, lizards, turtles, birds, plants and grit. The identification of each stomach item, and the dried weight, are listed in Table 1 and 2. In samples from Iriomote Island, 13 contents were found, but only three items were found from the Ishigaki Island samples. Crabs were the most common food items, and were identified from both islands. The results suggested that the eagles’ food items vary in accordance with the seasons. Also, considering the parasites also identified, it is suggested that the eagles fed on more food items that were not observed in their gastric contents.

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Herring Gulls Larus argentatus, Slaty-backed Gulls L. schistisagus, Common Gulls L. canus and Black-tailed Gulls L. crassirostris were observed to forage a reddish compound on the concrete wall of a berth at the Choshi fishing port, Chiba Prefecture, on 27 February, 2011. A high concentration of lead was detected in this compound. The lead was speculated to have come from incinerated ash used for reclamation in the 1960s. By spontaneously eating lead, this foraging behavior by gulls seems to be an example of allotriophagy, which is the abnormal consumption of a substance not typically considered as food. At the site of the consumption, the birds did not show any symptoms of poisoning, but it may be expected to affect their reproduction and survival rates.

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We observed a Glossy Ibis Plegadis falcinellus on Tokashiki Island, Okinawa Prefecture, Japan, on May 6, 2014. Although this species has been observed in Japan occasionally, the Check-List of Japanese Birds (7th revised edition) has those records suspended because it is possible that those observations were of escaped individuals. This latest record provides further evidence that the species naturally occurs in Okinawa.

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The sex of 51 Great Cormorants Phalacrocorax carbo (23 males, 28 females) were determined by necropsy, and seven measurements from the skulls were recorded to develop a process by which to determine the sex of skull specimens. The seven skull measurements included the following:
LUM= Length from the tip of the beak to the frontonasal hinge
MIW= Minimum interorbital width
WPP= Width between the postorbital processes
MWCP= Maximum width of the cerebral prominence
WZP= Width between the zygomatic processes
WPPE= Width between the paroccipital processes at the posterior end
LS= Length of the skull

All measurements from necropsied males measured significantly longer than those of females. Skull measurements were calculated to identify the sex of unknown Great Cormorant skull specimens. Formulas for determining the sex of Great Cormorant skulls were:
Z= -0.9066xLUM+2.1497xLS+0.3386xMIW-214.5102
Z= -1.4283xLUM+2.5528xLS+3.2109xWPP-318.8841
Z= -1.1873xLUM+2.2508xLS+2.3136xMWCP-273.4371
Z= -0.7515xLUM+1.9100xLS+1.2840xWZP-232.7216
Z= -0.7419xLUM+2.0227xLS+0.6296xWPPE-222.9565
Z=0.5930xMIW+2.1102xWPP+1.8790xMWCP+1.9484xWZP+0.0079xWPPE-193.9309

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