The contribution of each member toward incubation and chick-caring was examined within six bigamous trios of the Black-winged Stilt Himantopus himantopus; three trios with joint-nests, two trios with two-simultaneous-nests, and one trio with three-successive-nests. The study extended over a ten-year period from 1997-2007. In the first joint-nesting trio, composed of two parents and a yearling daughter, only the parents incubated the eggs. In the second joint-nesting trio, composed of three adult birds, all members attended one nest, but the dominant female sometimes drove the subordinate female out of the nest when the latter was incubating. In the third joint-nesting trio, composed of two parents and a yearling daughter, all members participated in incubation cooperatively. In bigamous trios with two-simultaneous-nests, one was composed of two parents and a yearling daughter, and the other composed of a male and two females. All members of these two trios participated in incubation of eggs in both nests. In the bigamous trio with three-successive-nests, composed of a pair and an unrelated female, the male attended all three nests, the dominant female attended the first and third nests, and the subordinate female attended the second and third nests. In a joint-nest situation, it seems to be difficult physically for an individual to incubate all eggs of two clutches laid in a single nest. In two-simultaneous-nests and three-successive-nests, the males performed a greater proportion of incubation in the nests of dominant females than in those of the subordinates. In the Black-winged Stilt, the hatching success of bigamous trios did not differ significantly from that of monogamous pairs. One bigamous trio with a joint-nest, one trio with two-simultaneous-nests, and one trio with three-successive-nests were successful in hatching chicks. In the first two cases all members of the respective trios contributed to defending chick-caring territory. In the trio with two-simultaneous-nests, all members participated in brooding, guarding chicks and sentry activities. Bigamous trios are more successful than monogamous pairs in chick-caring activities.
We describe for the first time the nest and eggs of the Calayan Rail Gallirallus calayanensis. The nest was built on the ground at the base of a fig tree and loosely constructed with dried leaves and stems. The eggs were pale pink and blotched reddish-brown and dark lilac, measuring 35 mm×25 mm in size. Nest placement, construction and egg coloration was similar to its congener, the Okinawa Rail G. okinawae.
On 17th May 2009 an individual Brewster's Brown Booby Sula leucogaster brewsteri was observed and photographed, on Nakanokamishima Island, a breeding ground for six seabird species, including the related subspecies S. l. plotus. Diagnostic characteristics of the individual included a whitish head, cheeks and throat, becoming gradually pale brown on the neck. The coloration of the facial skin around the eyes was rich blue, which is characteristic of the male. The absence of dark mottles on the normally white area from the lower breast to belly, which constitute juvenile and immature stages, indicate that the individual was an adult. This is the first record of this subspecies from Japan.
Predation by a wild Common Kingfisher Alcedo atthis on a colubrid snake, Amphiesma vibakari vibakari, was observed on 31 January 2010 in Tokyo. Total length of the snake was estimated as less than 20 cm. This is the first record of predation on a snake by the Common Kingfisher in Japan.
Two-barred Greenish Warblers Phylloscopus plumbeitarsus were observed and photographed on Hegura Island (37°51′05.1″N, 136°55′06.2″E), Ishikawa Prefecture, on three years: from 24th to 25th May in 2000 (3 individuals), on 20th May in 2001 (1 individual) and from 24th to 25th May in 2005 (3 or more individuals). They were distinguished from similar species (the Arctic Warbler P. borealis, Green Leaf-warbler P. nitidus, Greenish Warbler P. trochiloides, Pale-legged Leaf-warbler P. tenellipes, Sakhalin Leaf-warbler P. borealoides and the Large-billed Leaf-warbler P. magnirostris) by differences in the shape of the supercilium and wing bars, in the color of the legs, bill, and tip of the outer tail feathers, in their call, and in the wing structure. I also summarized the records of P. plumbeitarsus in Japan based on the data from the literature and personal communication. Eleven records (15 individuals or more) were obtained from 13th September 1998 to 29th May 2009 and seven records (11 individuals or more) occurred in mid and late May in 1999 to 2009.
A single Spotted Sandpiper Actitis macularia was observed alongside a river at Atsunai (42°48′ N, 143°49′ E), Urahoro, eastern Hokkaido from 17 May to 18 May, 2003. This is the first record of this species in Japan.
Observation of the breeding Great Crested Grebe Podiceps cristatus was carried out at two small man-made irrigation ponds, Shin Pond and Mochinosawa Pond, in Aomori Prefecture. A pair of grebes bred every year at Shin Pond from 2006 to 2009, and at Mochinosawa Pond from 2008 to 2009, respectively. The apparently same pair bred in Shin Pond for four successive years. Pairs in both sites attempted second broods within a breeding season. The absence of conspecific competition for diet or nesting-sites, and the presence of abundant fish in these two sites might facilitate these attempts at second broods.
In April 2009, the surviving family of the late Mr. Ichiro Kawai donated bird skin, egg and nest specimens to the Yamashina Institute for Ornithology. Mr. Kawai was a naturalist who lived in Yamagata Prefecture and died in January 2009. His collection consists of 51 skins of 29 species, 114 clutches of 70 species and 14 nests of 10 species. From the 1920s to 1960s, these specimens were mainly collected from Yamagata and Oita Prefectures in Japan, and from overseas.