Influence of Wetland Landscape Structure on Duck Nest Success at Malheur National Wildlife Refuge, Oregon

摘要

The decline of waterfowl populations and their requisite wetland habitats remains a concern. Because migratory bird refuges are often artificial landscapes of actively managed wetlands, and wildlife populations experience their greatest change during the breeding season, refuges should be designed to maximize breeding habitat. While past nest success studies have focused on at-nest variables, new approaches are needed to evaluate the effect of composition and configuration of plant communities at the landscape scale. This study aims to quantify landscape patterns within individual refuge management units to determine influence upon historical nesting success averages of ducks at Malheur National Wildlife Refuge in southeastern Oregon. The Mayfield estimate of nest success for 8 duck species yields a survival rate of 25% for the years 1987-1998 with a range of 0-74% across 48 management units. FRAGSTATS was used to calculate a suite of 9 landscape pattern metrics per unit at the class-level for each of 3 wetland habitat classes, and at the landscape-level using all habitat types. These 36 variables were tested for association with survival rate using Pearson R correlation. Results suggest fragmentation of dry meadow habitat; patch size, complexity, and extensiveness of wet meadow habitat; and diversity of habitats across the landscape positively influence duck nest success at the scale of the individual management unit.