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Monday, April 9 • 10:15am - 10:30am
TERRESTRIAL-AQUATIC ECOSYSTEM INTERACTIONS: Mallard Distribution and Wetland Network Modularity in the Prairie Pothole Region (PPR)

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AUTHORS: Jessica Gorzo*, Chris Wright – Natural Resources Research Institute

ABSTRACT: Distance thresholds define habitat connectivity for waterfowl, which vary during the stages of their annual cycle. During the breeding season, many species of waterfowl in the Prairie Pothole Region (PPR) of the U.S. require a complex of wetlands within their home range for nesting, foraging and brood rearing. Ideal spatial configuration and requisite distances between wetlands within the breeding site are largely unknown, yet likely drive larger-scale patterns of waterfowl distribution. Mallard (Anas platyrhyncos), the most common species in the PPR, are driven to settle breeding sites by conspecific attraction. Suitable habitat changes inter-annually with the spatially dynamic wetland conditions in the PPR. We aimed to test if annual mallard “hot spots” correlated with modularity of wetland networks at various spatial scales, and if correlations between hotspots and wetland network metrics varied according to inter-annual weather conditions. We used the Global Surface Water Layer (GSWL) to identify and map wetlands in the PPR, generated by the European Union via remote sensing imagery of 30-m resolution. The raster dataset spans 1984-2015, which includes high variability from severe drought through wet years in the PPR. We built upon the work of Janke (et al. 2017), who performed a hot-spot analysis annually during the study period from the Waterfowl Breeding Population and Habitat Survey (WBPHS). We investigated the relationship between mallard hot/cold spots (measured via a Z-Score from the Gi* test, spdep package in R) and characteristics of wetland network modules at 1km, 5km and 10km scales using regression trees and random forests. We found that network characteristics better predicted mallard Z-Scores than raw measures of wetland number or density within the vicinity of the survey segment. The most influential scale of wetland network modules varied with weather conditions, and thus characteristics of the networks local to each segment in a given year.

Monday April 9, 2018 10:15am - 10:30am CDT
LaSalle 1 (7th Floor)

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