Northern Prairie Wildlife Research Center
Table 4. Percentages of bird days (BD) and bird days per ha in refuges and non-refuges on the Ouse Washes, 1970-1971 (adapted).
Up to January 31 includes the hunting season and after February 1 is post-hunt. Results for mallard (Anas platyrhynchos) and Eurasian wigeon (Anas penelope) are typical for dabbling ducks, with only 13% and 17% respectively of the bird days spent in non-refuge areas up to January 31. Post-hunt, about two-thirds of mallard and Eurasian wigeon use days are spent on land formerly hunted. Duck days per ha spent in refuges before January 31 are 19.6 times that of non-refuges for mallard and 14.5 times that for Eurasian wigeon. After January 31, proportions are reduced to 1.4 times and twice respectively. Common moorhen (Gallinula chloropus) distribution is similar with about 3 times as many moorhen days per ha being spent in refuges as in non-refuges. Common pochard (Aythya ferina) were equally distributed in the two areas before January 31, mainly using unshot boundary rivers; post-hunting they used non-refuge areas. Surveys for these calculations were taken weekdays biweekly to avoid concentrations of waterfowl at refuges on weekends, thus use of refuges really is smaller than shown.
Refuges Non-refuges (490 ha) (1424 ha) %BD BD/ha %BD BD/ha
Before 31st Jan Mallard 751,000 87 1,333 13 67 Wigeon 2,136,000 83 3,618 17 250 Common pochard 16,000 21 7 799 Moorhen 45,000 47 43 53 16 After 31st Jan Mallard 368,000 32 240 68 173 Wigeon 1,963,000 40 1,602 60 812 Pochard 167,000 0 0 100 115 Moorhen 29,000 51 30 49 10
U.S. Department of the Interior |
U.S. Geological Survey
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