\nThe Daily Yomiuri,\u00a0Japan\u00a0– 12 hours ago
\nThe Yomiuri Shimbun<\/p>\n
A private group that observes swallows has discovered the birds begin building nests simultaneously in three regions each year, a finding that challenges the established theory that their nest-building areas move north as the temperature rises.
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\nThe regions are in eastern and western Japan divided by a line connecting Chiba and Niigata prefectures, and Kyushu. Until now, it had been assumed areas where swallows begin building nests go northward across the Japanese archipelago as temperatures rise, and a line called the “swallow front” would move northward gradually.<\/p>\n
However, findings of the group, Tsubame Kansatsu Zenkoku Network, or national network of swallow observers, might pull the rug from under this theory.<\/p>\n
The network examined the times and places where the swallows began building nests each year. About 630 cases over three years were reported to the network.<\/p>\n
According to the network, swallows begin building nests in Kyushu in the middle of February. In the region west of the line between Chiba and Niigata prefectures, nest-building begins between the middle of March and the first half of April. In the region east of the line including Hokkaido, nest-building begins about one month later, or in the first half or latter half of April.<\/p>\n
A nest-building front was not observed in any of the three regions. There does not seem to be a relationship between nest-building time and temperatures that influence the emergence of insects the swallows eat, the network said.<\/p>\n
“There hasn’t been any reliable nationwide research on the issue. It would be interesting if the [swallow] front doesn’t exist,” said Assistant Prof. Go Fujita at Tokyo University’s School of Agriculture and Life Sciences.<\/p>\n","protected":false},"excerpt":{"rendered":"
The Daily Yomiuri,\u00a0Japan\u00a0– 12 hours ago The Yomiuri Shimbun A private group that observes swallows has discovered the birds begin building nests simultaneously in three regions each year, a finding that challenges the established theory that their nest-building areas move north as the temperature rises.<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[413],"tags":[],"yoast_head":"\n