1. Which Places Do Cranes Choose to Live In?
Not all continents have cranes. Crane species live on every continent except Antarctica and South America [1]. They do not live on all continents.
Cranes use open water areas. Depending on the species and the season, they use environments like wetlands and grasslands [1]. Cranes use wide water areas where they can see their surroundings. So, which places in Japan do cranes use for their lives?
2. Red-crowned Cranes: Scattered in Summer, Gathered in Kushiro in Winter
In summer, Japan's Red-crowned cranes are distributed mainly in the wetlands of eastern Hokkaido. Their breeding grounds spread across Lake Kutcharo, Sarobetsu Wetland, and the Tokachi River basin [2]. In summer, they scatter across the wetlands to build nests and raise chicks [2].
However, in winter, most individuals gather in the Kushiro region [2]. They use rivers and spring-fed ponds as night roosts, and maintaining these sites is part of the protection plan [3].
The domestic population is estimated at about 1,650 birds (based on an NPO survey in 2018), while the global population is estimated at about 3,050 birds [2]. Dividing 1,650 by 3,050 gives approximately 0.54, which is slightly more than half. However, these two numbers are estimates from different years, not a ratio from the same year. This is a rough guideline. Scattering in summer and gathering in one place in winter: what does this difference mean for those trying to protect them?
3. Why Winter Feeding of Red-crowned Cranes Can Cause Crowding
Red-crowned cranes were once thought to be extinct. However, a dozen or so birds were rediscovered during the Taisho era, and numbers increased due to protection efforts since then. By around 1993, the population had recovered to about 600 birds [3].
Winter feeding began successfully in Akan Town and Tsurui Village in 1952, and local people have continued it since [2]. However, during the wintering period, more than 90 percent of the individuals concentrate at feeding sites. It is pointed out that if an infectious disease occurs, the number of birds could suddenly drop. The Ministry of the Environment is working to reduce feeding amounts and disperse wintering grounds [2]. Feeding intended to increase numbers has also created a new worry: too much crowding. Do cranes in other places have the same problem?
4. About 10,000 Cranes Winter on the Izumi Plain in Kagoshima
From mid-October to around March, about 10,000 Hooded cranes and White-naped cranes migrate to Izumi Plain from Siberia and other regions. Starting around late January, they begin returning to breeding grounds in Russia, Siberia, and northeastern China [4].
In the second survey on November 30, 2024, 12,992 birds were confirmed (12,036 Hooded cranes, 948 White-naped cranes, and 8 birds of other species). Exceeding 10,000 birds has happened for 28 consecutive years [4]. However, the number is not the same every year.
Ministry of the Environment materials state that Hooded cranes migrating to Izumi make up about 90 percent of the world's population (about 8,000 to 10,000 birds), and White-naped cranes make up about 50 percent (about 2,000 to 3,000 birds) [5]. Another source lists Hooded cranes at 80 to 90 percent, showing a range in the numbers. The 12,036 Hooded cranes counted in 2024 are more than the "about 8,000 to 10,000 birds" global estimate. This is because the source stating the ratio and the year of the count are different. It is safer to view the ratio as an approximate guideline. What does the situation of most of the world's cranes gathering in one place mean for those trying to protect them?
5. Why Conservationists Worry About Cranes Wintering in One Place
In records from just after the war, 275 cranes were recorded at Izumi. After more than half a century of protection, the number is introduced as having grown to exceed 10,000 birds [6]. Compared to the 12,992 birds in 2024, this is about 47 times more. However, the survey methods may not be consistent, so this is a rough guideline.
Hooded cranes and White-naped cranes are designated as a Special Natural Monument: "Cranes of Kagoshima Prefecture and their migration sites" [6]. On the other hand, the concentration of migration in one place raises concerns about mass death from infectious diseases [6].
For both the Red-crowned cranes in Hokkaido and the cranes in Izumi, increasing numbers through protection and the worry of too much crowding are two sides of the same story.
6. Using a Map and a Calculator to Check Where Cranes Gather
Look for Kushiro in Hokkaido and Izumi in Kagoshima Prefecture on a map. You can see with your own eyes that the wintering places for cranes gathering in specific spots are in eastern Hokkaido and southern Kyushu.
Divide the 1,650 Japanese Red-crowned cranes by the global total of 3,050 to get about 0.54. Compare the 275 cranes just after the war with the 12,992 cranes in 2024 to see it is about 47 times. You can check with your own hands what numbers are being compared.
The Ministry of the Environment materials on Red-crowned cranes and materials on Izumi are the sources for the numbers in this article. The fact that numbers change from year to year is described in more detail in the original sources.