Analysis of Wisconsin Wood Duck Banding Data 1959-75

Abstract

Data from 33,025 wood ducks banded throughout Wisconsin and at 5 major banding areas, 1959-75 were analyzed. The Upper Mississippi River contained most of the banded sample of young wood ducks. Adult banding was distributed evenly between the Upper Mississippi, Horicon and Necedah. Young male and female, and adult female recoveries were dominant in October and adult male recoveries were dominant in January. Most recoveries obtained during October from all cohorts, occurred in Wisconsin. Recoveries from all cohorts peaked during the first 10 days of October. Males were recovered in southern states earlier in the hunting season than females. The first 2 days of the Wisconsin waterfowl season were most important for recoveries from all areas and cohorts. Most recoveries had been obtained after the first 21 days of the hunting season. Wisconsin was the most important recovery state for its own wood ducks. The Mississippi Flyway contained most of the recoveries from Wisconsin wood ducks. Young males and all age females were recovered to the greatest extent in the Mississippi Flyway. Adult males were the dominant cohort recovered in the Atlantic Flyway. The southern states of Missisippi, Arkansas, Louisiana and eastern Texas were jointly responsible for 45 percent of all non-Wisconsin direct recoveries and 37 percent occurred in the northern states of Minnesota, Iowa and Illinois. Young were recovered in northern areas to a greater extent than adults. Direct and indirect recoveries show females were more likely to be recovered at the area in which they were banded than males. Thus males apparently migrate before females, and females tend to come back to the same area more than males. Direct recovery rates for adult and young wood ducks 1959-75 were 0.06 and 0.09 respectively1 ranging from 0.05 (Necedah) to 0.11 (Mead) for adults, and from 0.07 (Necedah) to 0.13 (Mead) for young. Direct recovery rates varied significantly between years. Mean kill rates for adult and young wood ducks were 24 and 34 percent, respectively. Wood ducks at Mead had the highest kill rate and those at Necedah had the lowest. Hunting mortality within and outside of Wisconsin made a significant contribution to total hunting mortality. BROWNIE survival rates for wood ducks banded throughout Wisconsin were 53 and 36 percent for adults and young, respectively. Johnson survival rates for the major banding areas ranged from 51 (Horicon) to 66 (Crex Meadows) percent for adults and from 33 (Upper Mississippi River) to 49 (Horicon) percent for young. The average of young survival rates for Horicon, Necedah and Crex Meadows was 46 percent and may be more representative of Wisconsin than a young survival rate of 36 percent. Date of opening day of the Wisconsin waterfowl hunting season and the number of October hunting days were correlated to adult and young kill rates within Wisconsin. Total season length, total bag limit and the number of active waterfowl hunters in Wisconsin were correlated to young kill rates within Wisconsin. Kill rates were generally greater in years when regulations (wood duck bag days) were liberal as compared to restrictive years. Average adult kill rates under the point system were greater than kill rates under the bag limit system, while young kill rates under the point system were greater than the most restrictive bag day category (30-50}. In years when the kill rate within Wisconsin decreased, the total kill rate also decreased. Reducing the kill rate within Wisconsin by opening the hunting season late in October would thus decrease the total hunting mortality on Wisconsin wood ducks. A population model for Wisconsin wood ducks indicates that under the 1959-75 survival and hunting mortality rates the-population would have been able to increase by 26 percent annually. Thus the Wisconsin wood duck population appears to be fairing well.