Reintroduction of the Oriental White Stork Ciconia boyciana in Tajima District, northern Hyogo Prefecture, Japan began in 2005. By June 2017 the population had exceeded 100 individuals including 12 breeding pairs, one of which fledged young in Tokushima Prefecture, on Shikoku Island. In this paper, we describe the process of reintroduction and establishment of the stork population. From 2005 to 2017, 51 captive bred birds were released, 136 birds fledged in the wild and two immigrated from the Asian continent bringing the population to 189 birds, of which 119 (60%) survive now in the wild in Japan. The characteristic features of this new population are: more than half are immature birds younger than three years old; 80% are solitary floaters including many solitary adults of both sexes. The sex ratio is greatly skewed toward females caused by the skew among fledglings. The higher survival rate of females compared with males seems to have caused this, but it is not clear if mortality in the wild is higher among males than females because direct impacts, both positive and negative, affect the storks inhabiting villages near human residences.
To conserve paddy field fish communities and the foraging habitats of Oriental White Storks Ciconia boyciana, a wetland area connecting the Kamatani River to a fallow field biotope (paddy area) was created by means of fishways and a permanent deep water area within the biotope in Toyooka City, central Japan. This ecological network had the following positive effects on paddy field fish species: 1) Gnathopogon elongatus elongatus became more abundant in the upstream habitat following restoration; 2) G. elongatus elongatus and Carassius spp. reproduced for the first time in the biotope after restoration; 3) C. spp. and Misgurnus anguillicaudatus utilized the fishway to swim up to the biotope; 4) current-year juvenile G. elongatus elongatus,C. spp., and M. anguillicaudatus grew in the biotope, and 5) adults and juveniles overwintered in the biotope, and Oryzias sakaizumii especially assembled within the deep water area. After restoration, storks regularly visited the biotope to forage. Additionally, one pair nested near the biotope and fledged five young during the 2016–2017 breeding seasons. The young birds and their parents continued to forage frequently in the biotope. Thus, our results indicate that ecological networks for paddy field fish communities contribute greatly to the foraging and breeding habitats of reintroduced storks.
We investigated the number of individuals and biomass of aquatic animals as prey for the Oriental White Stork Ciconia boyciana in winter paddy fields in Tobadani, Wakasa Town, Fukui Prefecture. Analysis of the prey biomass revealed that the red swamp crayfish Procambarus clarkii was most abundant, followed by the oriental weather loach Misgurnus anguillicaudatus and Odonata larvae. It is known that storks generally prey on these taxa. Aquatic prey animals were more abundant in plowed paddy fields with a rough surface than in plowed fields with smooth surfaces or in unplowed fields. The results suggest that the temporary puddles made when plowing boggy paddy fields provide suitable habitats for these aquatic animals.
Stork-Friendly Farming Methods (SFFM) were developed in paddy fields in the Tajima District, Kinki, as part of the reintroduction program of the Oriental White Stork Ciconia boyciana. Based on historical farming techniques characteristic of this region, represented by the use of cattle dung compost and winter flooding, SFFM aims to minimize agricultural dependency on chemical fertilizers and pesticides while exploiting the beneficial ecosystem that arises from the climate of the Tajima District. During the course of implementation of this farming method, various positive effects on both the Oriental White Stork and rice production were observed indicating a harmonious fusion of ecology and economy. Here we present in detail the merits stemming from the application of ecological science to agriculture, a holy grail of sustainable farming. The effort of spreading SFFM among farmers is also mentioned.
The Ogasawara Islands are subtropical oceanic islands in the Northwestern Pacific. Since their unique ecosystem is recognized to have outstanding universal value, they are registered as a UNESCO World Natural Heritage site. However, human settlement since 1830 has seriously impacted the biota. So far, the breeding of 20 land birds and 21 seabirds, including three introduced species, has been recorded on the islands. Seven endemic species/subspecies have become extinct, and breeding populations of five species have disappeared completely. Such extinctions have been caused by habitat loss, overhunting, and alien species invasion. Specifically, alien mammals are thought to have had devastating effects on avian populations. At least ten mammal species have been introduced, five of which (goats, cats, black rats, Norway rats, and house mice) still occur there today. Owing to their serious ecological impacts, eradication programs have been implemented. Feral goats had spread to 20 islands, but have been completely eradicated from all except Chichijima. Feral cats currently exist on only four islands and are being removed from natural areas on Chichijima. Non-native rodents have invaded almost all of the islands. Eradication programs using rodenticide are ongoing on some of the islands and have succeeded on four of them. After successful eradication, some land birds and seabirds have increased in numbers and expanded their distribution. However, undesired results also have been confirmed. For example, invasive plants have increased following goat eradication due to the elimination of grazing, and increasing seabirds have become dispersers of alien plants with adhesive seeds. Rat populations have likely increased after cat eradication due to their release from predation. These accumulated experiences should inform future adaptive management of the islands based on scientific evidence of specific species interactions.
There is growing evidence that invasive species can be eradicated from small islands. This allows us to recognize that eradication as a realistic target for invasive species management. If the findings obtained from such projects form the basis for other projects, we may raise the overall level of invasive species management. In this review, I introduce an outline of mongoose eradication on Amami-Oshima Island, a project that has reached the final phase towards eradication, and I describe the findings obtained during the course of the project. Based on these findings, I have produced a generalized roadmap for invasive species management, divided into five phases. It is necessary that tactics should be updated in the course of any such project according to the varying population status. I have shown that it is important to establish a governance design that promotes breakthroughs to proceed to the next phases. In order to realize this, a collaborative system is needed involving government, researchers, and residents. Finally, I provide a practical checklist for invasive species management. The roadmap and checklist presented in this review offer guidelines for examining the concept and direction of various ongoing invasive species management projects.
During inhabitation from 1881 to 1994 grazing and agricultural lands were widely established on the Mukojima Group of islands. Although Mukojima, Nakoudojima and Yomejima, the main islands of the group, were widely covered by forest before human settlement, damage caused by feral goats, such as grazing and trampling, caused deforestation and soil erosion. Feral goats were eradicated from the islands during the period from 1999 to 2003. Alien Black Ratswere also eradicated from Mukojima in 2010, although they still survive on Nakoudojima and Yomejima. In order to evaluate changes in seabird breeding status after goat removal, the numbers and distribution of nests of each species were recorded at three to four year intervals. After goat eradication, large-size ground nesters such as Brown Booby Sula leucogaster and Black-footed Albatross Phoebastria nigripes, have increased remarkably on islands where moderate populations had survived, whereas only limited increase has occurred on islands where initial populations were small. The Wedge-tailed Shearwater Puffinus pacificus, a mid-sized burrow nester, has shown outstanding increases regardless of the initial population sizes. Bulwer's Petrel Bulweria bulwerii, a small-sized burrow nester, whichdid not initially occur on all islands, has colonized two islands. The populations were, however, relatively small, and the limited increase may have been limited by rat predation. Because these population increases and range expansions have occurred over a relatively short time span, direct disturbance by feral goats, such as trampling, seems to have affected seabird breeding, rather than their indirect effects through environmental alteration. Responses to goat eradication varied among species. The three species that showed greatest recoveries each preferred open habitats such as grass and rocky areas. Before human settlement, forest breeding seabirds would have been common in natural forest environments. Thus the current avifauna is biased towards those species that breed in open habitats. To recover the original avifauna, it is necessary to promote forest restoration and rat eradication.
Zooarchaeology is the branch of archaeology that helps reconstruct the human past using animal remains from archaeological sites. These remains are also useful for reconstructing the palaeoecology of animals. In Japan, although several archaeozoological studies have focused on temporal changes in the size and distribution of mammalian species, there have been few archaeornithologial investigations of bird species. More than 600 avian species, with diverse ecological traits, have been recorded in Japan. Various responses to temporal environmental changes are thought to have occurred throughout the evolutionary history of birds; thus, we expect to find different ecological adaptations in birds to those seen in mammals. The identification and morphological, histological, genetic, and geochemical analyses of bird bones reveal several aspects of their palaeoecology, such as their distribution, morphology, population structure, genetic diversity, and food habits. Archaeornithological research on the Short-tailed Albatross Phoebastria albatrus revealed that the species was once distributed in the northern part of the Sea of Japan and the southern part of the Sea of Okhotsk. Furthermore, results show that there were two distinct albatross populations, with differing body sizes and food habits, about 1,000 years ago, and that the descendants of these populations now live on Torishima and Senkaku islands, respectively. Such findings provide essential information for directing conservation policy for this vulnerable seabird, which might in fact consist of two species. Whole genome analyses, using next generation sequencing, and collagen peptide identification will be applied to the analysis of archaeological bird bones to further archaeornithological research. Ornithological research has advanced mainly with regard to evolutionary and ecological time scales. Information obtained via archaeornithological research fills the gap between these time scales, making this field as valuable in Japan as it is elsewhere.
The Eurasian Woodcock Scolopax rusticola is a nocturnal game bird that rarely vocalizes outside the breeding season. It overwinters in a broad area of Japan, from Honshu to the Ryukyu Islands. Lack of population information is an issue when considering the conservation management of this species in Japan, making it important to develop effective monitoring methods. The Ministry of the Environment has drawn up a manual for spotlight survey to confirm its presence; however, distribution and population estimation methods using presence-only data obtained from such censuses have not been developed. To estimate the distribution and population size of the woodcock, we conducted a spotlight survey and constructed a maximum entropy model on Sado Island, Japan. Cultivated rice fields form the main foraging habitat of woodcocks on Sado Island. Woodcocks were more likely to be found in areas with large fields and high average temperatures. The model estimated the existence of 36.8 (25.12–43.12) km2 habitat on Sado Island, and predicts 79 (54–92) wintering individuals. From conservation efforts for the Crested Ibis Nipponia nippon on Sado Island, it is known that the amount of biomass, including earthworms, has increased as a consequence of environment-friendly farming. The quality of rice fields available as foraging sites for woodcocks could be improved by further environment-friendly farming. The combination of spotlight survey and maximum entropy model shown in this study is effective for monitoring the distribution and population trends of this species. It will be necessary to monitor the distribution of woodcocks across the country in order to conduct conservation management of the species by implementing wildlife protection areas and temporary game preserves.
Bird–proof netting is widely used in lotus fields in Japan in order to prevent damage caused by feeding waterbirds. In this study, we examined the effect of the netting on waterbird invasions into lotus fields along with other environmental factors, using Generalized Linear Mixed Models (GLMM). We counted the number of ducks (Anatidae) and Eurasian Coot Fulica atra at night in 80 lotus fields in Ibaraki Prefecture, Honshu. Surveys were conducted six times each in spring (February–March) and autumn (October–December) in 2011. In the model analysis, the type of the netting did not affect the number of ducks or Eurasian Coot. The amount of harvest residue positively affected the numbers of ducks in both seasons, and the distance from the nearest lake negatively affected the numbers of Eurasian Coot and positively affected the numbers of Eurasian Wigeon Anas penelope in both seasons, and Mallard A. platyrhnchos in spring. Thus, netting was not an effective means of preventing waterbirds from feeding in fields. In addition to the proper installation of netting, it is important to consider the factors attracting birds to the fields.
Eurasian Tree Sparrows Passer montanus feed on the nectar of cherry blossoms Cerasus x yedoensis without carrying pollen. This nectar-robbing behavior causes the blossoms to fall prior to pollination. Since cherry blossoms are cherished in Japanese culture, the public may be disturbed by nectar-robbing sparrows. We estimated blossom damage by sparrows in Goryo-kaku Park in Hakodate City, Hokkaido, Japan, a famous cherry blossom viewing spot. We estimated that the proportion of flowers caused to fall because of sparrows was 0.19% to 0.49% of all flowers.
In the residential area of Kanazawa City, Ishikawa Prefecture, the total number of individual birds that were observed water bathing, sand bathing, or drinking was recorded from 2010 through 2017. For Eurasian Tree Sparrow (3,875 individuals) water bathing peaked in September, sand bathing peaked in August, and drinking peaked in June. Over the course of a day, water bathing peaked at 14:00, and sand bathing and drinking both peaked at 18:00.
We determined total mercury concentrations in feathers of fish-eating Ospreys Pandion haliaetus (adult n = 1; nestling n = 1), from Hokkaido, Japan. Feathers from the approximately five week old nestling, had an Hg concentration of 1.84 µg/g (dw). Feathers from the adult (found on the ground near the nesting tree) had a higher concentration of 5.17 µg/g (dw). Both levels were within the range of concentrations previously reported from osprey feathers in Japan and North America. This discovery highlights the need for further study to examine the extent of mercury exposure of Ospreys in Japan.
During ringing of Eurasian Tree Sparrows Passer montanus in Hokkaido, three adult birds were recaptured. The colour of the basal part of the bill was black in one individual and yellow in two. Field studies show that juveniles have yellow bills, but both adults and young have black bills during June and July. From September to December, all birds developed yellow on their bills indicating seasonal change in bill colour. Male sparrows were significantly heavier with longer natural wing and tail lengths than females. Sex can be distinguished by a natural wing length of 67.7 mm and the probability of correct discrimination was 90%.
Kuchinoerabu-jima is a volcanic island in the Osumi group of islands in southwest Japan, which has dense natural vegetation, local endemism, and species diversity. However, with the exception of two reports from 1974 and 1977, the avifauna of the island is poorly known. We surveyed the bird assemblage of Kuchinoerabu-jima in 2017 and found 34 species in seven orders, including 11 newly recorded species. Species composition differed considerably between the 1970s and 2017, with species preferring forests having increased whereas those preferring open land had decreased. The avifauna of Kuchinoerabu-jima may have changed over recent decades due to landscape changes on the island.
The foraging behavior of the Blue Rock Thrush Monticola solitarius was investigated along a rocky coast in Niigata Prefecture. Thrushes were found foraging not only along the rocky shore, but also on sandy beaches, grasslands, and in forest adjacent to the shore. In each habitat their main foraging habitat was confirmed as open ground, where their primary prey consisted of animals smaller than 3 mm in length. The thrushes were confirmed as general predators of small animals living on open ground. The species' foraging behavior along a rocky coast was consistent with the species' foraging ecology in urban inland area.