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Northern Prairie Wildlife Research Center

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Homing and Reproductive Habits of Mallards,
Gadwalls, and Blue-winged Teal


Nasal Marker Biases

Return rate and homing rate estimates were biased low to the degree that some resident hens probably returned and were not identified, or returned without bill markers. We recaptured 116 hens, mainly mallards and gadwalls, that had bill marker attached 2-36 months previously. The marker loss rate averaged 4% for 49 birds recaptured 2-11 Months after marking, 5% for 33 birds recaptured 12-20 months after marking, and 19% for 34 birds recaptured 21-36 months after marking. All recaptured hens without markers were remarked.

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