The scientists have shown that migrating adult sparrows can find their way to their winter nesting grounds even after being thrown off course by thousands of miles.

　　The team first brought 30 sparrows to Princeton from northern Washington State，where the birds had been in the process of migrating southward from their summer breeding grounds in Alaska.Half the birds were juveniles（少年）of about three months in age that had never migrated before，while the other half were adults that had made the round trip to their wintering site in the southwestern United States at least once.

　　After the birds were released，they attempted to resume（重新开始）their migration，but both age groups grew disoriented（迷失方向的）quickly.

　　“All the birds scattered at first，” Wikelski said.“It was clear that they were turned around for a couple of days.But while the adults eventually realized they had to head southwest，the younger birds resumed flying straight southward as though they were still in Washington.”

　　“The adults，” said team member Richard Holland，“recovered their bearings because they possess something the younger birds do not，which is an internal map.”

　　“These birds need two things to know where they are and migrate effectively：a ‘map’ and a ‘compass’，”said Holland，a postdoctoral research associate in Wikelski's lab.“What we've found is that juveniles use their compass，but the adults also use their map.”

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