The Ostriches Of Fukushima And What They Told Us About Radiation
The Asahi Shimbun
Masato Kino, now 50 and an economy ministry official in charge of decommissioning and radioactive water issues, returned to the area on Sept. 23, 2011, six months after the magnitude-9.0 earthquake that hit the northeastern Tohoku region, triggered devastating tsunami which in turn knocked out cooling systems at the plant and caused the nuclear crisis. He was flabbergasted to come across an ostrich peeping into a private home from its yard in Okuma, Fukushima Prefecture.
It later emerged that the bird had escaped from an ostrich park in Okuma, situated 7 km from the Fukushima No. 1 plant.
Yoshihiro Hayashi, director-general of the National Museum of Nature and Science, who was involved in research on animals affected by the disaster, asked ornithologist Hiroshi Ogawa, an animal husbandry professor at the Tokyo University of Agriculture, for advice. In response to the offer, Ogawa began examining how the six ostriches trapped in January and May 2012 had absorbed radioactive substances.
It was assumed the feral birds feasted on contaminated plants, bugs and rainwater, so Ogawa tried to see if there was a way of reducing radioactive substances in their bodies by feeding them radiation-free dog food and well water. Although the ostriches should have been kept in an area where radiation levels were significantly lower, transferring animals from the no-entry zone was prohibited. As a result, they were cared for at Tomizawa’s stable in the restricted area. The birds displayed a radiation reading of 4.6 microsieverts per hour when the research started in March 2012. To lower the figure, Tomizawa frequented the stable from Saitama Prefecture once every one or two weeks to give them clean food and water. The six ostriches were finally euthanized and dissected one month, two and a half months, nine and a half months and 14 months after they were caught, respectively, so that changes in radiation levels in their bodies could be analyzed.
The results showed that almost no radioactive substances other than radioactive cesium derived from the Fukushima crisis remained in their bodies, meaning that they were free from strontium and other more dangerous materials.
The cesium reading began dropping nine and a half months after the birds were captured, which suggests the radiation level will drop if the animals are kept under low-radiation conditions. “The research provided insights into internal radiation exposure and drops in the radiation level of wild animals.”