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Habitat Restoration for the Reintroduction of Oriental White Storks
Kazuaki NAITO* and Hiroshi IKEDA
Institute of Natural and Environmental Sciences, University of Hyogo
128 Nigatani, Shounji, Toyooka 668-0814, Japane-mail: kaznait@stork.u-hyogo.ac.jp*corresponding author

Abstract
Oriental white storks (Ciconia boyciana) became extinct in Japan in 1971. After successful breeding in
captivity, a pilot release program was started as the first step toward reintroduction in 2005 in the Toyooka
Basin, the last region this bird inhabited in Japan. As the oriental white stork is carnivorous and uses avariety of animals in its diet, restoration of its foraging habitat is an important part of the reintroduction
project. Although this bird chooses good foraging sites seasonally in response to shifting habitat conditions
and the amount of prey available, paddy field systems, including ditches and shallow rivers are relatively
important to its foraging. At present, several restoration projects have been established in the Toyooka Basin.
To ameliorate the habitat quality of paddy fields, a new farming scheme, including installation of“fishways” connecting paddy fields and ditches, prolongation of the period of paddy field flooding andapplication of reduced amounts of agricultural chemicals, was introduced to local areas in 2002. In addition,a project to create a shallow riverbed along the side of the Maruyama River in the Toyooka Basin was begun
in order to improve the river channel to prevent flooding and to restore wetland habitat. These projects arebeing performed with the collaboration of local stakeholders.
Key words: Ciconica boyciana, habitat restoration, oriental white stork, paddy field, reintroduction

1. Introduction
The oriental white stork (Ciconia boyciana) is one of
the largest birds in Japan, with a wing span of up to twometers. Its breeding territory extends from the Amur to
the Ussuri River in east Siberia, and an estimated 3,000
individuals still exist worldwide (Litvinenko, 2000). According to the IUCN (International Union for Conservation of Nature and Natural Resources) red list, however,the survival of this species is still in peril. Although it
was once found throughout Japan, during the Second
World War it gradually decreased, until a reproducing
population survived only in the Toyooka Basin. The surviving individuals continued to decrease after the war,
consequently becoming extinct in 1971. A captive breeding project was started for the conservation of oriental
white storks in 1965. After the first breeding success in
1989, the captive population reached nearly 100 individuals in 2002. A pilot release as a step toward reintroduction was started in 2005. Conservation of oriental white
storks began with a focus on breeding techniques inorder to increase the number of individuals and maintaingenetic diversity in the population through establishment of different breeding pairs. With the start of thereintroduction project, habitat restoration emerged as a
big problem and, at present, several restoration programs
have been established in the Toyooka Basin.
Global Environmental Research
11: 217-221 (2007)
printed in Japan

2. Foraging Sites and Prey Animals ofOriental White Storks
The oriental white stork is carnivorous and preys on
a variety of animals. According to our study, the oriental
white stork used to occur throughout the entire Toyooka
Basin (Fig. 1) before its extinction and its foraging sites
seemed to include paddy fields, ditches and rivers inrural areas. Until the test release of the oriental white
stork, little was known on where and how the storks
would use rural areas as foraging sites, because the wild
population had been extinct for so long. Fortunately, awild individual of this species flew into the basin in
August 2002, revealing that the relative importance of
foraging sites changed seasonally (Fig. 2). Namely, it
mainly used paddy fields during May to July, when the
paddy fields were flooded. The ratio of foraging time inpaddy fields was about 80% in June, the maximum forthe year. The foraging sites shifted to sown grasslands
along the Maruyama River around September, then to
shallow areas of the river during winter. This indicatesthat oriental white storks choose good foraging sites
seasonally in response to shifting habitat conditions andamounts of prey animals. According to our observations,the prey animals of wild and released oriental white
storks included loaches, Carassius species, frogs(including tadpoles) and red swamp crayfishes©2007 AIRIES

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K. NAITO and H. IKEDA

Fig. 1 Sites where the oriental white storks were observed (Naito et al., 2002).
This information was collected through a questionnaire distributed among
retirees in the local population.

Fig. 2 Seasonal changes in foraging sites of a wild oriental white stork that come to Toyooka Basin in 2002.

(Procambarus clarkii) in flooded paddy fields andditches. They also ate insects such as grasshoppers anddragonflies in dry paddy fields and sown grasslands
along the Maruyama River and freshwater fish in
shallow areas of the river. They also occasionally caught
snakes.

3. Habitat Restoration for Oriental White
Storks
3.1 Reconstruction of the ecological pyramid
Large, long-lived, top-predator birds such as theoriental white stork require a large amount of prey animals to survive. An ecological pyramid had beenHabitat Restoration for the Reintroduction of Oriental White Storks

presumably formed up with the oriental white stork as atertiary consumer (Fig. 3). The bird requires various
habitats, since it uses different types of foraging sites
seasonally. Re-establishing a wild population of oriental
white storks means reconstructing a biological community comprising an ecological pyramid which has thestork as the top predator. As this ecological pyramid
once collapsed due to the heavy use of toxic agriculturalchemicals and deterioration of habitat, it must bereconstructed through habitat restoration prior to thereintroduction of the oriental white stork.
3.2 Current status of the paddy field ecosystem andits restoration
What is the current status of the Toyooka Basin fromthe view of the oriental white stork’s prey animals? A
study of the density of the prey animals in paddy fields
and ditches in the Toyooka Basin found that the density
was lower in the paddy fields than in the ditches (Naito& Ikeda, 2004, Fig. 4).
The main reason for the difference in densities was
the irrigation and drainage system actively implemented
in almost all of the paddy fields in the Toyooka Basinsince the 1960s as part of land consolidation projects,
which led to the deterioration and loss of habitat ofaquatic animals. Nevertheless, paddy fields are still

Fig. 3 Ecological pyramid indicating former, current andfuture habitat situations.

May 2001

Jun.

Sep.

Jan. 2002

Fig. 4 Seasonal changes in prey animals in
paddy fields and ditches.

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important as foraging sites because they cover most of
the area of the basin, thus restoration would presumably
have a big effect. In consideration of the reintroductionof the storks, at several sites duck farming has been
carried out as an alternative rice farming method thatuses ducks in place of agricultural chemicals to control
weeds and pests. Because duck farming is more laborintensive, its employment has been limited in scope;
therefore a more practical rice farming scheme is neededin order to cover a broader area.
3.3 A new rice farming scheme for the oriental
white stork
To ameliorate the habitat quality of the paddy fields,
a new rice farming scheme was introduced to certain
areas in 2002. The Toyooka Agricultural Extension
Center developed the scheme, using either reduced or no
agricultural chemicals and alternative water management, i.e., flooding the paddies more deeply with water,
keeping the water in them longer than in conventional
rice farming methods and using compost and other natural resources (Nishimura, 2006). It is considered amethod of producing rice while raising aquatic animals
that could share the paddy fields. This scheme wasadopted at 157 ha of paddy fields in the basin in 2007,
and the product has been recognized by consumers as ahealthy and safe value-added rice. Key to this schemefrom the view of restoring habitats is installation of fishways connecting paddy fields and ditches, extension of
the flooding period of the paddy fields and applicationof reduced amounts of agricultural chemicals. Amongthese measures, the fishways have proven indispensable
and since a synergistic effect may be expected, they
have been adopted in many areas where the new rice
farming scheme was introduced.
3.4 Continuous watering and biological communities of paddy fields
In conventional rice farming, the paddy fields holdwater for only a short period of time, from several days
prior to planting to several weeks afterwards, and thenare drained off. Some regions of Japan, however, haverecently adopted a method in which the fields areflooded for a longer period of time with the aim of restraining weed growth, softening the soil for non-plowing cultivation and creating habitats for waterfowl. The
scheme adopted in the Toyooka Basin requires flooding
after harvesting, and holding the water in the fields until
the next rice planting season, with the extra-farming aimof creating habitat for aquatic animals. This water
management scheme increased the benthos biomass
particularly of red worms (tubificids) and chironomids(Toyooka City, 2006), as has been found in other regions
where the same management has been carried out. This
increase in benthos biomass probably contributes to thesurvival of other animals that use benthos species asfood resources, which in turn may increase the preybiomass for the oriental white stork.

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3.5 Agricultural chemical reduction and its effect on
biodiversity
The Toyooka Agricultural Extension Center andlocal farmers made a brief investigation of the fauna ofseveral paddy fields with differing amounts of applied
agricultural chemicals. This investigation revealed thatnatural enemies of pest insects, such as praying mantises,
spiders and dragonflies, were more abundant in paddy
fields in which no agricultural chemicals had been
applied (Fig. 5). These results indicate that no or
reduced application of agricultural chemicals mayenrich the biological diversity of paddy fields, thus
providing more prey animals for oriental white storks.
There was no way we could easily estimate the effects
of non-use of agricultural chemicals, as there were otherfactors involved, including water management and useof different fertilizers in addition to application ofagricultural chemicals.
3.6 Flooding of paddy fields and its effect on frogs
The new paddy farming scheme adopted in Toyooka
includes postponement of the draining of paddy fields
for about two weeks, allowing tadpoles to metamorphose into frogs during this specific season. In Shounji,
the village adopted this method the soonest, and the density of black-spotted pond frogs (Rana nigromaculata)
increased during 2002 to 2005 (Toyoola City, 2006). In
this village, certain paddy fields were set aside and filledwith water throughout the year in 2001 to be restored as
biotopes for aquatic animals. In addition to thesebiotopes, the number of constantly flooded paddy fields
increased considerably in 2004. This probably reflects
the result of habitat restoration projects. Such trends,
however, did not occur in neighboring areas, indicatingthat the density of frogs was also influenced by otherfactors on the landscape scale, such as distance fromforest edges, distribution of residential areas and dryfields, habitat fragmentation by roads, etc.
3.7 Restoration of temporally flooded areas
The greater part of the Toyooka Baisn was originallya floodplain of the Maruyama River and consisted of a

Fig. 5 Density of major animal species in paddy fields
with differing amounts of agricultural chemicals.
Data from the Toyooka Agricultural Extension
Center.

network of wetland habitat. The plain, however, wasfragmented when most of it was turned into paddy fields,
and has undergone further land consolidation projects
since the 1960s. The Maruyama River has also been
modified by construction of shortcut river channels,
banks and high-water channels as part of river improvement projects, resulting in a decrease in temporally
flooded areas. As many freshwater aquatic animals
reproduce in temporally flooded areas, which are predator-free and rich in food resources, the habitat deterioration and destruction of temporally flooded areas had aconsiderable impact on such aquatic animals.
Two projects to reconstruct ecological networks inthe floodplain have been underway. One involves creating small-scale fishways connecting paddy fields withditches. As a result of land consolidation projects, theditches were located more than one meter lower than thesurface of the paddy fields. This makes it hard foraquatic animals, especially fish, to move between theditches and the paddy fields, even when the paddy fields
are filled with water, so they cannot reproduce in paddy
fields. The fishway project started in 2003, and a total of
94 fishways had been built as of March 2007. An
investigation to monitor the results revealed that several
kinds of freshwater fishes, such as loaches (Misgurnus
anguillicaudatus), catfish (Silurus asotus) and Carassius
sp., entered paddy fields via fishways and reproduced
there (Naito et al., 2005). The lone wild stork and somereleased oriental white storks have been observed inpaddy fields in the Akaishi area, where fishways wereintensively installed, implying that they recognizedthese paddy fields as richer than the other paddy fields
without fishways.
The second project involves creating a shallow riverbed alongside the Maruyama River. The lower reachesof the Maruyama River are extremely flat, so the
Toyooka Basin suffered from repeated flooding. Intensive river drainage improvement construction has beenongoing since 2004, when a typhoon caused extraordinary flooding. River channel improvement includes
dredging the riverbed so that water not exceeding thedesign limits can be discharged and excavating a dry
riverbed, called a “high-water channel,” which is higher
than the river channel and is usually not filled withwater, so that flooding will inundate this particular channel when waters have risen above the design limits ofthe former channel. Because this high-water channel canbecome adequate wetland for reproduction of aquatic
animals and for foraging by oriental white storks, thisexcavated riverbed can serve as both flood prevention
and habitat restoration. According to our investigation,
the density of prey animals in the river was lower thanthat in the paddy fields or ditches. The wild oriental
stork fed in the shallows, usually 20-50 cm in depth, inthe river mainly during winter. Prior to the project, there
were few such shallow areas in the river, and the total
area was also limited. The shallows created under the
project will ultimately reach three times the area of theoriginal. Monitoring will be needed to ascertain

Habitat Restoration for the Reintroduction of Oriental White Storks

persistence of the shallows created, the dynamics of theaquatic community and the functionality as a foraging
site for the oriental white stork.

4. Social Framework of Restoration
Recently, some laws of Japan have been changed, including the River Law (1997), the Basic Law on Food,
Agriculture and Rural Areas (1999) and the Land
Improvement Act (2001), to indicate the necessity ofattention to the condition of the environment in executing public projects. Further, the Law for the Promotionof Nature Restoration was established in 2003 to authorize restoration projects as part of public works. As thislaw promotes participation of the stakeholders, including local people, in restoration projects, public involvement has become a common trend in such projects.
These social changes have encouraged restoration
activities for the reintroduction of oriental white storks.
In addition, constitutional frameworks have also been
established in local administrations. In 2002, both
Toyooka City and a local branch of Hyogo Prefecture
created sections that handle restoration activities andreintroduction projects in each organization.
The oriental white stork needs a habitat range
containing rural landscapes covering various kinds ofland, whose land use, owners and/or management
schemes differ. Therefore, reintroduction of oriental
white storks cannot be considered separately fromsociological aspects such as our lifestyles and restoration of local society (Kikuchi, 2003; Naito et al., 2004).
From this point of view, in 2003 the various stakeholders in regional management, which included such
entities as administrations, researchers, companies, local
parties, residents and NPOs, organized a promotion
committee for the reintroduction of the storks in order todiscuss reintroduction plans and form public consensus
and to perform restoration activities as participants(Committee for the Reintroduction of the Oriental White
Stork, 2003). The restoration activities mentioned above
are an outcome of the discussions of the committee.

5. Conclusion
In the test release, a total of 19 individuals were released in 2005-2007. According to our monitoring, thereleased individuals have often foraged in paddy areas
where the new rice-farming scheme was introduced. On
the other hand, many individuals visited the rooflesspens in the breeding facilities (Homeland) for the oriental white stork and ate the fish provided for the captive
individuals, mingling with them. Some individuals
depended on additional food in their activity range, because we fed them in order to have some individuals
stay in particular areas or to have them eat supplemental
food during nesting season. An individual released in2006 and two done in 2007 did not depend at all on foodhandouts. It foraged for loaches, crayfish and small
insects in paddies and ditches during the winter of the221

year it was released. The reintroduction project is now
in the first stage of establishing a wild population of theoriental white stork. Restoration in different areas aswell as in different types of habitat should be encouraged in order to create more stable foraging sites.
References
Committee for the Reintroduction of the Oriental White Stork(2003) Action plan for the reintroduction of the oriental white
stork. Committee for the Reintroduction of the Oriental White
Stork.
Kikuchi, N. (2003) A study about the relationship between local
people and the oriental white stork in the Tajima District,Hyogo Prefecture: Reviewing the terms “Turu” and“Konotori.” Journal of Environmental Sociology, 9:153-170.
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Litvinenko, N.M. (ed.) (2000) Oriental white stork in Russia. Far
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