Yomiuri: Japanese crane population heading for a crash?
...Japanese cranes used to be seen everywhere in Hokkaido, but the number of the species continued declining due to overhunting and land development that decreased the marshland areas where the birds are based. At one point, it was believed the species had become extinct. In the 1920s, however, more than 10 cranes were found alive. A 1952 study showed there were only 33. Since around that time, however, local people...started feeding the birds in each region, spreading protection efforts among other people. Thanks to such efforts, the number of the birds topped 1,000 in 2006. Researchers say there are now 1,200 Japanese cranes in Hokkaido. Japanese cranes live on the northern island all through the year and breed in the summer...However, the birds' increasing population cannot be attributed to improvements in the natural environment. Kushiro Shitsugen's groundwater level is falling, and its area is shrinking due to development and deforestation in and around the marshland. In the past 60 years, the marshland area has decreased by 30 percent, while the area of alder woods, thought to be an indicator of aridification, has quadrupled...There is another possible problem. If a large number of the same species are concentrated in one area, it becomes very difficult for them to survive purely on the food they can get in the wild and this increases the risk of massive die-offs due to deadly infectious diseases. The ministry is considering expanding their habitat by adjusting the places and seasons cranes are fed, as well as the quantity of the feed...more...
