images.library.wisc.eduimages.library.wisc.edu/EcoNatRes/EFacs/PassPigeon/ppv15...bird, may actually...
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images.library.wisc.eduimages.library.wisc.edu/EcoNatRes/EFacs/PassPigeon/ppv15...bird, may actually be more tolerant to winter conditions. It is the au- thor's opinion that the phenomenon