Stork Reintroduction in Toyooka: 40 Years Back to 500 Birds

What kind of bird is the Oriental stork? A top predator of Japan's wetlands

A large wading bird with a wingspan near 2 metres

The Oriental stork (Ciconia boyciana) is a large waterbird of the stork family. It is about 110 cm long with a wingspan approaching 2 m. White with black flight feathers and red skin around the eyes, it is a carnivore that walks through shallow water catching fish, amphibians and insects. It was once seen in paddies and wetlands across Japan and, like cranes, was cherished as an auspicious bird.

While the white stork of Europe nests on utility poles and chimneys, Japan's storks have long nested in tall trees such as pines. This habit is why artificial nesting towers later became important in the reintroduction.

Daily food needs and the paddy as a feeding ground

Being large, storks need a lot of food. They eat a variety of small animals such as loaches, crucian carp, frogs, crayfish and grasshoppers, so they cannot live without shallow waters rich in preyIn Japan's rural landscapes, paddies, channels, ponds and rivers together have played that role.

• Feeding: shallow paddies, channels, riverbanks, wetlands
• Nests: tall trees (pines etc.); artificial towers are now also used
• Roosting and resting: woods near water and river sandbars
• Movement: East Asian populations move to and from the continent, but Japan's population is mostly resident

Why did Japan's storks go extinct?

Hunting and habitat change

Once seen across the country, storks declined through hunting, and their habitat shrank quickly as large pines for nesting were felled and wetlands and rivers were modified.

The Toyooka Basin (Maruyama River basin) became the last area in Japan where breeding was confirmed. Kobe Shimbun reports that urban development and pesticide use reduced numbers after the war and that the basin was the country's last breeding ground.

Pesticides and loss of prey: the high-growth era

The decisive factor was the worsening food environment. In the high-growth era pesticides came into wide use in paddies and the animals storks feed on declined. A Ministry of Land, Infrastructure, Transport and Tourism document also lists repeated heavy pesticide use among the causes, along with changes in farming and deforestation. It has been reported that during early captive breeding, older birds affected by pesticides died without hatching chicks.

1965 to 2005: about 40 years from captive breeding to release

The painful decision to capture wild birds

In 1965 Toyooka began captive breeding by capturing wild pairs. Capturing wild birds must have drawn strong criticism, but it was a choice made on the promise to return them to the sky someday. However, the remaining birds, burdened by accumulated pesticides and other factors, died one after another without hatching eggs.

When the last wild bird died in 1971, storks vanished from the wild in Japan. Young birds were later received from the former Soviet Union and became the basis of captive breeding. In 1989, the 25th year of Toyooka's artificial rearing, captive breeding finally succeeded, and chicks have hatched every year since.

Hyogo Prefectural Park of the Oriental White Stork and preparing for release

To return captive-bred birds to nature, it was necessary to prepare not just numbers but the environment they would return to. In Toyooka, the Hyogo Prefectural Park of the Oriental White Stork became the base for rearing, breeding, research and release training, and preparations advanced alongside work on local paddies, rivers and nesting towers.

• Genetic lineage management of captive birds and selection of birds for release
• Identifying individuals with leg bands and transmitters to track them after release
• Restoring paddies, channels and wetlands to increase prey
• Building cooperation among local farmers, government, researchers and residents

Five birds released in 2005

In 2005, five captive-bred birds were released for the first time in Toyooka. Hyogo Prefecture reports that the wild population exceeded 500 within 20 years of that release. At first the birds were still learning to find food, fly and avoid danger, and not everything went smoothly, but it was the first step toward a population living in the wild.

The "Stork-Nurturing Farming Method": turning paddies back into feeding grounds

Aims and basic ideas of the method

The "Stork-Nurturing Farming Method" born in Toyooka is farming that grows rice while making the paddy function as a feeding ground for storksmethod. Ministry of Agriculture, Forestry and Fisheries materials describe its differences from ordinary rice growing: careful water management from spring to autumn and winter flooding (filling paddies with water in winter).

• No pesticides (pesticide-free) or greatly reduced pesticides
• Winter and early flooding create habitat for frogs, loaches and aquatic insects
• Delaying midseason drainage (draining the field once during rice growth) to give animals time to grow
• Fishways so fish can move between paddies and channels

Acreage trend and results

According to Toyooka City, acreage was 407.1 ha in 2017 and 445.6 ha of rice in FY2022 (162.5 ha pesticide-free, 283.1 ha reduced-pesticide), a record high. The city has branded rice grown this way as "Stork-Nurturing Rice" and built a system that balances environmental care with sale prices.

Rice that carries "environmental value"

The spread of the method also matters for farmers' incomes. Environment-friendly cultivation takes extra work, so a system that buys the rice at a fair price is essential. Toyooka is seen as a pioneering example of an environmental economy that combines biodiversity conservation with farmers' livelihoods, and is a reference for efforts elsewhere.

From wild breeding in 2007 to over 500 birds: population trend

2007: the first chicks hatched on their own in the wild

In 2007, two years after the release, a wild pair hatched chicks on their own on an artificial tower. Chicks hatching in the wild for the first time in about half a century marked the turning point at which reintroduction moved from simple release to forming a self-sustaining population.

Growth of the wild population

• 2013: more than 70 birds living in the wild (Hyogo Prefecture)
• 2021: the Hyogo Prefectural Park announced that breeding-age birds aged 3 or older exceeded 50 for three years in a row
• End of July 2022: nationwide wild population passes 300
• June 2025: nationwide wild population exceeds 500
• End of November 2025: reported at over 550 nationwide

Beyond the Toyooka area, visits and breeding have recently been reported outside Hyogo, and their range is spreading nationwide. A widening distribution, however, requires each region to create feeding grounds and monitoring systems.

Nesting towers and community monitoring

Where tall trees such as pines have declined, artificial towers help storks nest. Setting up towers, tending nest material, watching fledging and tracking birds by leg bands are often done not only by researchers but also by residents and schools, nurturing a culture of a bird watched over by everyone.

Challenges ahead: genetic diversity, extreme heat and coexistence

Low genetic diversity

The wild population descends from a limited number of captive birds. This lowers genetic diversity and raises the risk of weaker resistance to future disease and environmental change. Kobe Shimbun also cites low genetic diversity as a challenge even as numbers grow. Introducing diverse lineages and exchange with overseas populations are being discussed.

Extreme heat and low rainfall change the paddy environment

The effects of climate change are also appearing. According to Kobe Shimbun, Toyooka's mean temperature in July 2025 was 29.4°C, far above the 26.1°C of July and August 1971, and rainfall was about one-tenth of normal, so water temporarily disappeared from paddies in the Maruyama River basin. Without water in paddies, prey animals cannot grow.

Preparing for crop damage, accidents and disease

As numbers grow, risks such as collisions with power lines, accidents and infections like avian influenza also rise. Reintroduction does not end with the release; it requires long-term management and dialogue.

Storks seen through the links between paddies, rivers and sea

The water cycle of the Maruyama River basin

Toyooka's paddies are part of the water cycle running from the Maruyama River to the Sea of Japan. Reducing pesticides and fertilizer in paddies also benefits the water quality of rivers, estuaries and coasts. For the link between rivers and sea, see also What links forest, river and sea: how river basins nurture a rich ocean

Paddies and the biodiversity of rural landscapes

Paddies, channels and ponds are secondary nature shaped over a long time by human activity. For paddy biodiversity, see Biodiversity of rice paddies; for how rural satoyama landscapes work, see What is satoyama? The cycle of woodland, paddies and ponds and the crisis of abandonmentfor details.

Another reintroduction: comparison with the crested ibis

On Sado Island in Niigata Prefecture, reintroduction of the crested ibis is under way. For details see the article crested ibis reintroduction. For both storks and ibises, restoring rural environments including paddies is a shared key.

What we can do: putting what we learn into daily life

Choose environment-friendly rice

Choosing rice grown without or with fewer pesticides, or products from wildlife-nurturing methods, is a concrete way to support producers. Look for products whose environmental care is certified or labelled, such as "Stork-Nurturing Rice".

Observe good manners when watching

• Do not get too close to nests or parent birds (observe from a distance)
• Do not feed them or bring drones near
• If you find a bird with leg bands or a transmitter, report it to the local contact or the Park
• Do not throw litter into paddies or channels

Join local activities

There are events you can join in Toyooka and elsewhere, such as observation meetings, paddy wildlife surveys and winter-flooding visits. Getting to know nearby waterside environments and noticing change gives strength to the next reintroduction.