The Prairie Pothole Region (PPR) provides critical habitat for breeding ducks via grasslands for nesting and wetlands for rearing broods. Landscape alterations including wetland drainage and intensive row crop agriculture have reduced habitat availability and thus reduced duck production, though the extent to which intensively-cropped landscapes within the PPR support and sustain duck production is largely unknown. To better understand the mechanisms driving wetland use among duck broods at multiple spatial scales, I (1) conducted brood surveys to assess wetland occupancy patterns by duck broods and (2) sampled wetlands to assess landscape-level invertebrate forage availability for duck broods across a range of wetland conditions in intensively-cropped portions of the U.S. PPR. I conducted 2 periods of repeat-visit brood surveys in the Iowa, Minnesota, North Dakota, and South Dakota PPR between late May to mid-August of 2018–2020 using a quadcopter drone equipped with a thermal and visual camera. I observed 507 broods across 413 unique wetlands. I observed 10 different species with 7 in the dabbling duck guild and 3 in the diving duck guild, however most broods were dabbling ducks (n = 471, 93%). Annual occupancy probability—or the probability a wetland was occupied by ≥ 1 brood throughout the breeding season—was 0.41 (95% CrI: 0.36, 0.46) and was invariant among states or between privately and publicly-owned wetlands. At the landscape scale, I observed a positive relationship between occupancy probability and the proportion of a 2 km buffer surrounding the wetland that comprised grassland. The amount of submersed aquatic vegetation (SAV), aquatic invertebrate biomass, and percent emergent vegetation influenced wetland occupancy by duck broods, though these effects were generally weak. With my strongest and most consistent predictor of occupancy, wetland wet area, I found a universal area response that predicted equivalent occupancy probabilities among many small wetlands or a single large wetland up to 7 ha. I found widespread invertebrate forage with no strong spatial patterns. I also observed a positive association with crop production surrounding the wetland and weak negative effects of internal wetland factors including the amount of SAV and maximum depth on invertebrate forage biomass. These results suggested wetlands in farmed landscapes can support key forage for ducklings. Collectively, my findings suggest conservation and restoration of small (≤ 10 ha) wetlands in crop-dominated landscapes, where wetlands may be a limiting landscape feature and invertebrates elicit a positive biomass response, could be an effective waterfowl conservation strategy largely independent of broader landscape contexts. Additionally, small wetland restoration efforts could dovetail with ongoing wetland restoration initiatives that employ similar basin sizes (i.e., ≤ 10 ha) to assist in a range of other environmental challenges wetlands help to resolve, such as nutrient-reduction for water quality, flood abatement, or provisioning opportunities for wildlife-associated recreation.
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