Regional difference in the diet of Slaty-backed Gulls, Larus schistisagus was studied at the colonies around Hokkaido, Japan. They fed their chicks with sardines Sardinops melanosticta, rock fish Sebastes spp., and seabird chicks on Teuri Island, sardines on Daikoku Island and sardines and sandlances Ammodytes sp. on Yururi Island. They preyed upon chicks of seabirds such as Black-tailed Gulls L. crassirostris, Rhinoceros Auklets Cerorhinca monocerata and conspecifics on Teuri Island, while they preyed upon adults of Leach's Storm-Petrels Oceanodroma leucorhoa on Daikoku, Yururi and Moyururi Islands. Although availability of conspecific chicks was higher on Daikoku, Yururi and Moyururi Islands than on Teuri Island, they preyed upon conspecific chicks more frequently on Teuri Island than on Daikoku, Yururi and Moyururi Islands. Thus, availability of conspecific chicks did not explain the regional difference in the occurrence of predition attempts on conspecific chicks.
The vocalizations of a nocturnally active seabird, Leach's Storm-Petrel (Oceanodroma leucorhoa), were studied at their breeding colony on Daikoku Island, Hokkaido, Japan. Three distinct call types were recognized, namely Chatter-call, Purr-call and Screech-call. All were vocalized by both male and female adults. Purr-call vocalizations and those of Screech-calls showed situation-specificities. In the burrows with Purr-call vocalizations, there were two heterosexual birds, but no broods were found. Therefore, this call may be associated with courtship behavior or pair formation. Screech-calls were always vocalized between two consexual birds and seemed to be vocalized during aggressive encounters. Chatter-calls were usually vocalized together with other call types and in various situations, although the aerial birds vocalized only this call type. But situation-specificities were recognized when these situations were divided according to the calls vocalized with Chatter-calls. Some discussion was made about functional interpretation of vocalizations in Leach's Storm-Petrels.
The present investigation was undertaken to understand the involvement of pineal in reproductive activities of the domestic pigeon, Columba livia. Activities of 17β, 3β and 3α-hydroxysteroid dehydrogenases were studied histochemically in the testis and ovary of normal and pinealectomised domestic pigeons during breeding (March, April and May) and nonbreeding seasons (June, July and August). Both the testis and ovary showed high activities of these enzymes during the breeding season as compared to the nonbreeding season in normal intact birds. Pinealectomy caused shrinkage of gonads during the breeding season and enlargement of gonads during the nonbreeding season. During the breeding season, pinealectomised birds showed low activities of all the enzymes which is well corroborated with the observed inactive shrunken condition of gonads. Increased activity of the steroid dehydrogenases during the non-breeding season in pinealectomised birds is indicative of the activation of gonads, which is well reflected by the observed enlargement of gonads. Apparently, the present results indicate that during the breeding season, pineal has a progonadal role while during the nonbreeding season it is antigonadal.
Application of discriminant analysis to sex determination in Manchurian Cranes Grus japonensis was discussed, using following four measurements from 8 males and 14 females; tail length (TL), wing length (WL), tarsus length (LL) and bill length (BL). Following discriminant function was obtained: Z=0.16887TL+0.01329WL-0.21827LL+1.06610BL-15.35077 Sex of the birds is determined by sign of this discriminant score (Z), as males when Z>0 and as females when Z<0. The difference of average score between 8 males and 14 females was significantly large (df=20, t=9.144, p<0.001). This method of sex identification in this rare bird using measurements in several parts of the body is thought to be useful at zoo or field because of its easiness and immediateness. However, collection of more data of body measurements and other items for measurement should be needed in order to obtain more accurate discriminant function.
The Pallas's Grasshopper Warbler Locustella certhiola was found to transit the Japanese Archipelago by two ringing records from Hokkaido and Kyushu recently. Both two birds seemed to be adults, sex unknown, and the second one from Kyushu appeared to belong to the subspecies rubescens by the coloration of the plumage, size and distributional range. This species is a very rare vagrant in Japan, but it is expected that further records will be reported by ringers.
Two observations of the woodpecker bill in captivity are reported. 1) A male Great-spotted Woodpecker caught as an adult lost most part of its upper bill (rhamphotheca). It repeated recovering in abnormal shapes and breaking off. 2) The upper bill of a young female Japanese Pygmy Woodpecker, caught as a nestling, abnormally elongated and became shorter to normal length in a month. These observations suggest that woodpecker bill can be modified easily by bird's foraging behavior.
A dead adult male Chinese Merganser Mergus squamatus was collected at the Agano River, Niigata Pref., 10 February 1987. This is the second record of this species in Japan, and the first specimen collected from Japan (The first photo record of a pair was from Kiso River, February, 1986).