It has been established that some interspecific hybrids among ducks and geese (Anatidae) strongly resemble one parent or even another species altogether, thus causing problems in field-identification. An extreme case in Britain is the hybrid Pochard Aythya ferina x Tufted Duck Aythya fuligula which can be very difficult to distinguish in the field from the American Lesser Scaup Aythya affinis (Per


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