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Trudy A. Chatwin, Monica H. Mather, Tanya D. Giesbrecht, Changes in Pelagic and Double-Crested Cormorant Nesting Populations in the Strait of Georgia, British Columbia, Northwestern Naturalist, Vol. 83, No. 3 (Winter, 2002), pp. 109-117
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Chatwin et al. (2002) studied this question.
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