A decline in bird populations was identified through analysis of audio tape recording data recorded in Karuizawa, central Japan, from 1989 to 2006. Blue-and-white Flycatchers and Jungle Crows populations increased during the study period, however, the populations of most other bird species decreased. Common Pheasants, Common Cuckoos, Oriental Cuckoos, Gray Thrush, Brown Thrush, Bush Warblers, Varied Tits, Siberian Meadow Buntings, Japanese Yellow Buntings and Black-faced Buntings were frequently recorded during the early part of study period, but they disappeared by the end of the period. The timing of the decrease was consistent with increased development in the study area.

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In order to determine the factors affecting wintering waterfowl populations, the number of wintering swans and ducks, the snow depth, and the minimum temperature during the period from 1984 to 2006 in northern Japan were analyzed. There were increasing trends in both in the swan and duck populations during that period. In the area of heavy snow along the Japan Sea coast, it was determined that the minimum temperature affected the wintering population of swans, and the depth of snow affected the wintering population of ducks. However, in the area of light snowfall along the Pacific Coast, there were few snow and temperature effects on wintering waterfowl. The minimum temperature may affect roost/resting sites through freezing, and the snow depth may affect foraging conditions. These results suggest that roost/resting site conditions may strongly affect wintering swans, and foraging conditions may strongly affect wintering ducks.

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In early 2006, a population crash of Tree Sparrows Passer montanus was observed in the central areas of Hokkaido, which is located in northern Japan. We devised a simple point count method to monitor the Tree Sparrow population and requested citizens and bird watchers, as well as researchers, to participate in the census. The reported abundance of Tree Sparrows had no regional difference between the Kanto Region of Honshu (3.6 birds/0.78ha) which has no snowfall, and Hokkaido (3.8 birds/0.78ha) which receives heavy snowfall. Tree Sparrow abundance in both regions was 3.6 birds/0.78ha in both summer and winter of 2006-7. The comparison between the sites with and without bird feeders in Hokkaido, however, showed a significant seasonal difference in sparrow abundance. A larger number of sparrows congregated at sites with feeders in winter. It suggests that sparrows would be more vulnerable to the spread of infectious diseases at feeders in winter in Hokkaido. Therefore, management rules should be established to maintain feeder hygiene and to limit the number of birds at the feeders. In order to continue this survey, the method should be simple and easy for citizens to carry out. In addition, the number of replicates must be large to control for a large variance. The future challenge of this approach is to increase the number of replicates (e.g. observers) in order to develop greater stability of data values, and to allow a larger number of factors that can be analyzed. Since Tree Sparrows are probably the most familiar garden birds in Japan, they serve as an indicator species of the environmental health of human habitats. Therefore, this census method is strongly recommended for schools and nature education programs.

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Digging as a foraging behavior of Bewick's Swans was observed only rarely in the rice paddy fields of Echigo Plain. Fecal analysis indicated that the food items consumed by swans during digging were primarily tubers of Eleocharis kuroguwai.

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The Crested Serpent Eagle Spilornis cheela perplexus mainly inhabits Ishigaki-jima Island and Iriomote-jima Island, southwestern Japan. We observed a juvenile eagle as an irregular visitor on Taketomi-jima Island (24°19'N, 124°04'E) on January 22, 2005.

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This study aimed to investigate the effect of Great Cormorant Phalacrocorax carbo activity at a colony site in the south of Lake Hamana, Shizuoka Prefecture, Japan. The study site was located where a large amount of Great Cormorant feces accumulated within the colony. The vigor of the trees and the structure of the plant community were estimated and recorded. In the colony, 86.8% of trees were estimated to be in a state of "weakened" vigor. Cormorants were often observed snapping twigs from those trees for nest material, and feces were frequently observed. These results suggest that the activity of Great Cormorants do affect the condition of canopy trees in the colony. A large number of Rhus succedanea saplings grew on the forest floor at the site, and those seedlings may possibly provide replacement canopy trees.

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Wrong:line 16: N=42,43; line 18: N=40,24
Right:line 16: N=40,24; line 18: N=42,43

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The Study of breeding ecology of birds using temperature sensors was conducted as a special feature for this issue. I hope that this special feature introduces many ornithologists to this valuable method of studying the breeding ecology of birds.

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We tested a temperature logger for monitoring the breeding schedule of cavity nesting birds, and concluded that they provided accurate and valuable data with which to deduce nesting activity. The temperature sensors were attached to the bottoms of the nest boxes for Ryukyu Robins Erithacus komadori, Varied Tits Parus varius, Great Tits P. major, and Red-cheeked Starlings Sturnus philippensis. The temperature data within the nest boxes were compared with ambient air temperatures. From changes in the temperature difference between the internal nest box temperature and the ambient air temperature (nest box - air temperature) we could deduce the start of incubation, hatching, and fledging for Varied Tits, Great Tits, and Red-cheeked Starlings. We could deduce those periods for Robin nests if we attached the sensor 1.2cm above the bottom. Therefore, specially designed attachment methods are needed for some species. These trial studies confirm that research on reproductive ecology can be enhanced by use of a temperature sensor and data logger when studying cavity nesting birds.

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Temperatures in a Ural Owl Strix uralensis nest box at Hashimoto (Wakayama Prefecture) were monitored by temperature data logger (thermo recorder) during the nesting season in 2007. The temperature data from 4 March to 30 April were analyzed, and the incubation period and the hatching dates of the chicks were estimated based on recorded temperature changes. After the incubation period began, the night temperatures in the nest box was always higher than that of outside. When hatching began, the temperature in the box rapidly increased, and then the maximum temperature exceeded 20°C, sometimes 30°C. It was possible to monitor the breeding stages of the Ural Owl by use of a thermo recorder.

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I attached0 temperature data loggers to 56 nests of the Madagascar Paradise Flycatcher Terpsiphone mutata to identify the nest predator and time of nest predation. The research was conducted at Ankarafantsika National Park in Madagascar in 2004 and 2005. Three species were identified as nest predators from video records which filmed the nests with temperature data loggers: Brown Lemur Eulemur fulvus, Frances's Sparrowhawk Accipiter francesii and Malagasy Cat-eyed Snake Madagascarophis colubrinus. The first two species predated nests in the evening, and the latter predated at night. The temperature inside the nest dropped sharply after each nest predation. In the case of predation by the Brown Lemur, the pattern of nest temperature change was different from that of the other two species, because the parent had left the nest more than 40 minutes before predation. The predatory species could not be identified by the change of nest temperature only. Nest predation primarily occurred at night, in the morning and the evening. The time of nest predation did not differ between incubation and brooding periods. From the present research, the temperature data logger is considered to be an effective tool to identify the time of nest predation.

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From the results of these three papers published in the special feature, "Study of breeding ecology of birds using temperature sensors", we have concluded that using temperature sensors is an effective method for researching the breeding ecology of birds. Video recording of nests gives us more detailed data for studying the breeding ecology than does the temperature sensor, however, it take long hours to review and analyze the video data. We can analyze temperature sensor data easily because we can download the data to computer. Furthermore, the sensor is inexpensive (less than 3000 Japanese Yen), and the sensor and data logger is reusable. Therefore, we recommend the use of temperature sensors for studying the breeding ecology of birds.

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