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Q.2-11: Mallard (Anas platyrhynchos) brood use of man-made wetlands in Southland, New Zealand

Presented by Erin Garrick - Email: erin.garrick@southlandfishgame.co.nz

The Southland region of New Zealand has numerous small (~1 hectare) man-made wetlands purposed for duck hunting, however, it is unclear how suitable these man-made wetlands are for mallard brood rearing. Our objective was to assess differences in mallard brood use of man-made wetlands based on wetland habitat characteristics. We selected 22 wetlands and stratified sites by the degree of overhead cover. Data was collected on variables including wetland area, perimeter, area-shoreline ratio, shallow feeding area, location of overhead cover (N,E,S,W), direction of weather exposure, percent of emergent vegetation, surrounding land use, invertebrate food abundance, whether the wetland periphery was grazed and whether the wetland was fenced. We monitored each wetland using game cameras and the time-lapse function, which took photos every five minutes during daylight hours from September to December 2015. We collected a total of 258,035 photos, and identified the most used wetland, which had ducklings present 11.7% of the time, and the least used wetland, which had no ducklings present throughout the term of the study. Linear regressions were used to identify variables that resulted in increased brood use of wetlands. Wetland usage by broods tended to increase with an increase in the ponds shallow feeding zone, cover reducing exposure on the west and south side of the wetland, overhead cover on the western edge of the wetland, and stock exclusion from the wetland. We recommend minimal earthworks, strategic planting, and fencing with stock exclusion to encourage mallard brood use of wetlands in Southland. Further analysis on the relationship between wetland habitat and duckling survival should be investigated.
Session: Poster Session 2 (Wednesday, August 28, 19:00 to 21:00)