The Black Woodpecker Dryocopus martius in Honshu, Japan, lost much of its habitat due to logging of native beech forests, mainly during the period of rapid economic growth during the 20th century. Black Woodpeckers occur only in a few areas of natural beech forest in the northern Tohoku region, although there is much uncertainty concerning the species' current distribution in Honshu. Details of the ecology of the woodpeckers in the region have yet to be unraveled. Here, I give a brief review of the history of research into the Black Woodpeckers in Honshu, and describe its ecology. My aim is to summarize what has been clarified so far and to present the issues that need to be addressed in future if this population is to survive. Black Woodpeckers forage on ants, mainly consisting of Camponotus obscuripes. The roles of both sexes in breeding are equally clear, although female woodpeckers are thought likely to choose their nesting sites. It has been reported that even when one of the pair dies, the remaining adult continues caring for the nestlings until they fledge. Fledglings are observed mainly in mid-June, with an average of 2.2 nestlings fledging per nest (close to the average number reported from West Germany). The woodpeckers use only live trees, the ecological reasons for which are unknown. Their nest holes are used by other birds and mammals, and the woodpeckers may play a role as a keystone species in their habitat. Observations of the Black Woodpecker in Honshu were reported in the Kanbun-Kinpu, published in the Edo period in 1831. Later researchers, such as Magojiro Kawaguchi, confirmed the species's occurrence in Honshu, and this became widely known. It is likely that gene flow between the major population of the species in Hokkaido and small populations in northern Honshu has always been limited. The Black Woodpecker population in Honshu is suspected of requiring urgent conservation activities. It is important to investigate the criteria that these woodpeckers use to select their nesting sites. For example, the characteristics of the environment around their nest trees, the diameter at breast height range of nest trees, the distance from lower branches to nest holes, the inclination of nesting trees, and the sizes of nest holes in Honshu are not well understood and require urgent study.
On the basis of several influential parameters, a simplified prediction method was proposed for the lengths of the diving period, Td, maximum diving period, Tdmax, and diving interval (pause spent on the water surface), Tp, of the Little Grebe Tachybaptus ruficollis. The parameters include the standard metabolic rate, tidal volume, minute ventilation, forced convection heat transfer, buoyancy force and hydrodynamic drag acting on the grebe. The equations thus derived as a function of the body mass could predict the three periods of the Little Grebe observed in this study with deviations of –7.2%, 3.7%, and 15.5%, respectively. The diving periods and diving intervals of the Australasian Little Grebe Tachybaptus novaehollandiae, the Hoary-headed Grebe Poliocephalus poliocephalus, and the Eared Grebe Podiceps nigricollis were predicted with nearly the same deviations as those for the Little Grebe. The equation for the maximum diving period agreed well with that derived previously from regression analysis.
We investigated the diet and chick body mass of Rhinoceros Auklets Cerorhinca monocerata at four breeding sites in Hokkaido in 2016 and 2017. Matsumae-kojima, Teuri Island and Todo Island are in the southern, middle and northern Tsushima Warm Current system, respectively, although Todo Island is located also beside the colder water mass of the Sea of Okhotsk. Daikoku Island is in the Coastal Oyashio and Oyashio Cold Current system in the North Pacific Ocean. The main prey species delivered in chicks were 0-yr-old (0 +) Arabesque Greenling Pleurogrammus azonus at Teuri and Todo Islnads, 0 + Walleye Pollock Gadus chalcogrammus at Matsumae-kojima and 0 + Chum Salmon Oncorhynchus keta at Daikoku Island. In addition some 0 + and > 0-yr-old sandlance Ammodytes spp. Were delivered at all sites. Parent auklets at Todo Island brought back heavier food-loads and fish species of greater energy density than those at other sites, resulting in greater developmental-stage adjusted chick body mass. Sea water temperature differences might explain the dissimilarity in the availability of 0 + greenling between Todo and Teuri Islands and the inter-year difference in the availability of 0 + salmon at Daikoku Island. The more active Chum Salmon hatchery program in the Pacific Ocean than in the Sea of Japan may also explain the regional differences in the importance of this species in auklet food-loads. In addition, sandlance are likely available in all coastal waters around Hokkaido. This study suggests that ocean environment and anthropogenic factors affect regional prey availability, and explain the regional differences in the diet and chick growth of the Rhinoceros Auklet.
Omnivorous gulls (Laridae) are known to feed on insects. Few studies have reported, however, how, when, and where they do so. In this study, we attached a GPS-video logger to Black-tailed Gulls Larus crassirostris during the breeding season. Video recordings were obtained of gulls capturing flying insects over land and sea. Some insects were identified as Ichneumonidae, Camponotus and Lepidoptera. Future improvements to video loggers may allow us to further understand the importance of insects in the foraging strategies of gulls and the hitherto unknown relationship between gulls and insects.