The Great Cormorant (Phalacrocorax carbo), a high-trophic level consumer in the wetland ecosystem, nests in the colonies sometimes in urban areas. Recent expansion of its distribution and the increase of the population size are presumably attributed to the changes both of the human activities and the wetland ecosystems in Japan. The Great Cormorants occurred widely throughout Japan before 1940, then both their ranges and numbers decreased, so that by the beginning of the 1970s this species was considered as threatened. Subsequently, however, the population size has increased gradually, then during the 1990s the population underwent rapid increase in numbers and spread widely. As a consequence, they gave impacts on forests where they nest and inland fisheries. In order to assess the extent of the current impacts and to control the damage, the four meetings were held between 1998 and 2001 during the annual meeting of the Ornithological Society of Japan. The meetings were steered by cormorant researchers, in which the coexistence of people and Great Cormorants was discussed. The special issues in this volume summarise the results of these meetings.

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The distribution and abundance of the Great Cormorant Phalacrocorax carbo in Japan have changed markedly. Before 1920 cormorants were widely distributed throughout Japan south of Hokkaido. From the end of 19th century to 1940s, cormorants decreased rapidly because of illegal hunting. After 1945, the expansion of human activities, development, and water pollution were the causes of further decreases in the cormorant population and range. In 1971, fewer than 3, 000 cormorants bred in just three colonies in Japan. From the late 1970s onwards, numbers of cormorants gradually began to increase; they formed sub-colonies or roosts in areas close to these three colonies. The main reasons for this increase are assumed to have included improvements to freshwater quality, progress in freshwater purification (which led to increased fish stocks), and reduced disturbance of cormorants by people. During 1980s cormorants began to disperse widely due to the culling for pest control in Aichi, Gifu and Mie prefectures. At present, there are an estimated 50, 000-60, 000 Great Cormorants in Japan, occurring from Oita prefecture in the south, to Aomori prefecture in the north.

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During the 1990s, the number of Great Cormorant (Phalacrocorax carbo) in Japan has been increasing. As a consequence, there have been increasing conflicts between cormorants and fresh water fisheries. We reviewed the species and size range of fish eaten by cormorants, examined their food requirements, and foraging site selection in the Kanto, Tokai, and Kansai areas of Honshu. Cormorants eat various fish species from fresh, brackish, or marine waters, depending on seasonal changes in food availability in each habitat. Cormorants generally eat fish measuring 3-30 cm in length. Each individual cormorant requires approximately 500 g of fish each day. Individual differences in foraging site selection were indicated by stable isotope analysis. A greater understanding of the foraging ecology of cormorants is necessary in order to manage the population and/or behaviour of this piscivorous bird effectively.

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The present paper reviews current knowledge on the effects of Great Cormorant (Phalacrocorax carbo hanedae) nesting and roosting on forest ecosystems. The intensity of their effects was considered dependent on the duration of their residence and their activity levels in forests. Field surveys and experimental studies showed that both plants and soils beneath colonies and roosts are affected by the deposition of feces, and damage to twigs and foliage (caused by flapping and trampling, and by collection for nest materials). These activities may change the interactions among plants and between plants and soil, and may affect the community structure of soil animals and fungi. This change of the interactions among biological/chemical and physical factors resulted in the changes of the succession of the plant communities. The mechanism causing the decline and death of plants, the succession of forest vegetation, the dynamics of plant community structure and biological interactions in the cormorant colonies and roosts are still unclear. A greater understanding of the basic ecological implications of cormorant nesting and roosting is essential in order to have management strategies for reducing damage on forests by cormorants.

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In this paper we outiline the history of toxic contaminants in wild birds in Japan. Pollution by dioxin and dioxin-like compounds has become a common issue in recent decades. As such pollution poses a considerable health probem, countermeasures and technology to reduce the impacts are important. Very few papers have so fare focussed on the effects of dioxin and dioxin-like compounds on wild life in Japan. For the purposes of our research, we selected the Great Cormorant (Phalacrocorax carbo). This fish-eating species nests colonially, and can be regarded as an indicator species of the effects of dioxins and dioxin-like compounds. We monitored cormorant health and compared it with published information on other. The cormorant residue levels were found to be higher than among other birds. The residue of PCDD/Fs consitsted mainly of 2, 3, 7, 8-substitution, in which 1, 2, 3, 7, 8-PeCDD and 2, 3, 4, 7, 8-PeCDF were the greatest contribution to toxic equivalency (TEQ). These compounds are accumulated more in the liver than egg and muscle. Based on the half-lives of dioxin and dioxin-like compound in the body of the cormorants, a decadal change of pollutant levels of their eggs was calculated using that of the environmental. It seems likely that embryo mortality, caused by dioxins, was the main toxic effect during the 1970s, but this declined dramatically over the following decades. We conclude that the estimated embryo mortality caused by PCDD/Fs and co-PCBs pollution (27%) was so small and would not impact population status. However, studies of the other end points such as LOEL of enzyme activity and immunotoxicity are still needed. Our sample size was small and it is desirable to monitor large number of birds with unlethal techniques.

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The Great Cormorants (Phalacrocorax carbo) have recently gave impacts on forestry and fishery in Japan. To decrease the population of this species, culling was operated in many locations, which appeared not to be so effective. These human-cormorant conflicts have not been mitigate easily because so many factors are contributed. The special animal management planning system will be applied in the future under the Wildlife Protection and Hunting Law.

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The home ranges and flock sizes of the Azure-winged Magpie Cyanopica cyana were studied during the non-breeding season in the Ina area (ca. 800 m alt.) from 1977 to 1981 and in the Nobeyama area (ca. 1350 m alt.) from 1980 to 1983 in Nagano Prefecture, central Honshu, Japan. The climate of the Nobeyama area was more severe in winter than in the Ina area. In the Ina area, the average home range size of ten flocks was 135.1 ha, while in the Nobeyama area five flocks average home ranges of 287.6 ha. The fall, winter and spring ranges of one flock in Ina area almost completely overlapped, but the range of the single flock at Nobeyama area expanded during winter and contracted in spring. The home ranges of neighboring flocks partly, or largely overlapped. The average size of ten flocks at Ina was 28.7 birds, while the average of five flocks at Nobeyama was 16.4 birds. The size of the Ina flock decreased over time, but that of Nobeyama remained the same. Population density was 9.6 birds/at Ina and 4.2 birds/at Nobeyama. Flock sizes in both areas were unstable during October, and decreased gradually from November to April. The flock size was reduced from October to April by the rate of 33.5% at Ina and 31.4% at Nobeyama, respectively. The difference in the home ranges of the flocks in the two areas may result from environmental factors such as weather conditions and food availability during winter.

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The Hazel Grouse (Bonasa bonasia) is a small forest grouse occurring in temperate and boreal forests from Scandinavia to the Far East. The species is assumed to have reached Hokkaido, northern Japan, via Sakhalin Island, during the last ice age about 40, 000 years ago. The subspecies occurring in Hokkaido is now recognisably distinct as B. b. vicinitas. Pairs are formed from late March to early May. During this period males whistle actively. Six to ten eggs are laid in early or mid-May and hatch in early June after incubation of 23 to 25 days. Young attain adult size by late August and have adult plumage by mid-September. The main diet consists of the leaves and seeds of herbaceous plants and trees and arthropods during late spring and summer, the buds of broad-leaved trees and vine fruits during autumn and winter, and buds and catkins in early spring. The Hazel Grouse has two large caeca supporting effective digestion of the plant fibers comprising their main diet. Hazel Grouse prefer broad-leaved and mixed forests with relatively dense undergrowth, and they avoid larch plantations in Hokkaido. Recently, the Hazel Grouse population has decreased in Hokkaido, the main cause of which is considered to be predation by the red fox (Vulpes vulpes), which increased in numbers from the early 1970s until the 1990s. Brood sizes were smaller during low population periods than during normal population periods. In order to maintain, or increase, Hazel Grouse population levels, habitat management and predator control is considered necessary.

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The authors captured and ringed a willow warbler at Mt. Takachiyama (28°09′51″N, 129°19′08″E) in Setouchi Town, Kagoshima Prefecture, southern Japan, on September 27, 2001. The bird was identified as this species from following morphological and genetic characteristics. Morphologically, the bird had no wing-bars and long tail (tail/wing ratio: 0.75), 6th primary (P6) was not emarginated, the outermost primary (P1) was longer than primary-coverts by 5.6 mm, and wing-point was 3rd primary (P3). Blood sample was taken with a micro-capillary tube from ulnar vein before releasing and was preserved in Queen's buffer (Seutin et al. 1991) at the ambient temperature. A part of cytochrome b sequence was determined using an automated DNA sequencer (Model 310, Applied Biosystems) following Leisler et al. (1997). The captured bird (GenBank Accession #: AB075024) differed from a European willow warbler (Accession#: Z73492) by 9 substitutions (1.5% sequence divergence), which is typical of a subspecies distance. The bird was probably race yakutensis judging from the distribution, but it could not be confirmed.

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