"10.1111/j.1365-2486.2008.01751.x" . "Variable shifts in spring and autumn migration phenology in North American songbirds associated with climate change"^^ . . "15" . "760-771" . "2009"^^ . "10.1111/j.1365-2486.2008.01751.x" . . . _:genid1 . _:genid1 . _:genid1 . _:genid1 . _:genid2 . _:genid2 . _:genid2 . _:genid2 . _:genid3 . _:genid3 . _:genid3 . _:genid3 . . . . . . .