Management of Riparian Habitats to Increase Duck Nest Success
in Southern Alberta
TOMASZ P. SANKOWSKI
Ducks Unlimited Canada, 1190 Waverley Street, Winnipeg, MB
R3T 2E2, Canada
Research suggests that when nesting cover is reduced to remnant patches which are easily searched by predators, duck nest success is greatly reduced. Predation rates are particularly high in narrow wetland fringes which provide attractive but not effective nesting cover. One of the management techniques utilized by Ducks Unlimited is to lease or purchase riparian habitat, maintain idle cover, and provide wider and perhaps more secure nesting habitat. The effectiveness of this management option was tested at the Antelope Creek Ranch near Brooks, Alberta, in 1988. Nest searches were conducted in wetland fringes and dry basin bottoms. Wet meadow vegetation such as tall grasses and sedges dominated wetland fringes while solid stands of cat tail dominated wetland bottoms. In wetland fringes, predation rates declined with distance from nest to water. In the first 25 meters, 80% of all nests were destroyed by predators while 72% of nests initiated between 25 and 50 meters from water were destroyed. However, the predation rate was only 44% for nests initiated more than 50 m from water. Mayfield success rates were 3, 7, and 21% in the three nest-water distance categories, respectively. This indicates that nest losses can be reduced by managing riparian habitats and providing wider zones of attractive cover further away from wetlands. Another management option is manipulation of water levels to provide stands of tall emergent vegetation for nesting. Predation rates in stands of dry cattail were considerably lower than in wetland fringes and also seemed to vary with distance between nest and water. Predation was highest (30%) for nests located in the first 25 meters but declined to 25 and 20% for nests initiated 25-50 meters and over 50 meters from water, respectively. Mayfield nest success ranged from 28% for nests located less than 25 meters from water to 39% for those initiated more than 50 meters from water. It appears that providing wider wet meadow zones around wetlands or dry stands of tall and dense emergent vegetation can be effective in reducing nest losses to predation.
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