HULSCHER JB (1992) Dutch Ornithological Union: Theme day from inside and outside Birds seen: Is the beak of the male Oystercatcher a better tool for mussels to open than that of the female?. LIMOSA 65 (3): 129-130.

Is the beak of the male Oystercatcher a better tool for mussels to open than that of the female Eurasian Oystercatcher Haematopus ostralegus Dutch Ornithological Union: Theme day from inside and outside Birds seen

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