Basic Factors Determining the Waterfowl Productivity on Three Prairie Ponds in 1947 |
Common terms and phrases
11 June acres Alisma April Aquatic Invert aquatic invertebrate August behavior Bennett Blue-winged Teal brood season bulrush cat-tail copulation courtship dense drake ducklings ducks duckweed flew flower Fond food samples Grebe growth Hochbaum inches indicated intruding June juveniles last week Lesser Scaup loafing spots loam Mallards Marsh Hawk migration period mortality normal number of males numbers of Blue-winged open water paired birds pasture period Pied-billed Grebe plant PLATE Pond II pondweed PONO population portion pre-nesting season predation present study Ramsey County ratios of Blue-winged ratios of Lesser reed meadow grass resident male Ring-necked Duck Sago Sago pondweed second week seen September sex ratios shore cover shore line shore vegetation shoreline showed species study area summer drought surface swam territorial defense third week three ponds tion total numbers Typha latifolia upland water areas water level waterfowl weed week of July winged Teal Wood Duck