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本帖最后由 细胞海洋 于 2013-9-5 09:30 编辑 $ p& Y1 X' K* P
( k X( M3 p# Z- z$ R5 }COVER Young whooping cranes (Grus americana) follow an ultralight aircraft. Each year, endangered whooping cranes are reared in captivity and artificially trained by ultralight aircraft on their first lifetime migration from Wisconsin to Florida. Analyses of data from subsequent unaided migration events show that migratory performance improves over many years and that social learning from older birds plays an important role. See page 999. Photo: Joseph Duff/Operation Migration USA, Inc.
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发表于 2013-9-4 14:45
