We used contemporary data of Aythya affinis (Lesser Scaup) and A. marila (Greater Scaup) (hereafter referred together as Scaup) to explore the utility of mark–recapture analysis to estimate annual abundance of Scaup at Great South Bay (GSB), NY, in winter 2019. We also used historic banding data to estimate temporal and spatial changes in Scaup banded along the north, mid-, and south Atlantic Coast regions during winter and recovered by hunters within <1 year. Capture bias of banded Scaup was substantial because we estimated ≤8130 Scaup on GSB using the upper 95% confidence limit of models, but regularly observed ≥30,000 near banding sites. We did not detect a spatial or temporal influence on Greater Scaup recoveries. Lesser Scaup recovery longitude differed by region and shifted 209 km east from 1920 to 2019.