Fred A. Johnson

Variation in Band-recovery and Survival Rates of Mottled Ducks in Florida

The failure to recognize heterogeneity in band-recovery and survival rates can lead to biased estimates and spurious inferences regarding population status. We examined band-recovery data for sources of variation in recovery and survival rates of mottled ducks (Anas fuhigula) in Florida. Distances between banding and recovery sites were small (median = 38 km), suggesting that mottled ducks live much of their lives within the same drainage basin. Recovery rates varied among regions of banding, perhaps because of spatial heterogeneity in bandreporting rates. Cohort-specific survival rates...


Waterfowl Habitat Selection on a Multipurpose Reservoir in East Texas

Aerial surveys were used to determine numbers of wintering waterfowl and their habitat preferences on Sam Rayburn Reservoir in East Texas during the winters of 1979 - 81. The magnitude of relative preference for 6 wetland types was defined as the mean difference between the ranks of wetland use and availability. A total of 23,277 waterfowl representing 14 species was tallied from 12 surveys. Mallard (Anas platyrhynchos), gadwall (A. strepera), American widgeon (A. americana), and teal (Anas spp.) were the most abundant species and composed 89.0% of the total Ducks preferred scrub-shrub,...