Lake Saint-Pierre (Québec, Canada) and its floodplain provide breeding and foraging habitat for diverse wildlife, particularly during annual spring flooding. From 1950 to 1997, the agricultural landscape of the floodplain underwent a major transformation, with the majority of the area previously under perennial crops (forage and pasture) being converted to annual ones (corn and soybean). A new land use map of the floodplain produced in 2016 provided an updated portrait of the wildlife habitat available. The reduction in the area under perennial crops that occurred from 1950 to 1997, continued after this period. In 2016, crops of this type accounted for only 2% of the portion of the floodplain exhibiting a 2-year flood recurrence interval, whereas they had occupied nearly a quarter of the area in the 1950s. Nearly 3,800 ha of wildlife habitat (perennial crops and natural habitat) have been altered since 1950, largely by conversion to annual crops, with an estimated net loss of 550 ha of wildlife habitat occurring between 1997 and 2016. Habitat restoration and the implementation of sustainable agriculture in the floodplain are needed to support the restoration of the ecological functions of the Lake Saint-Pierre ecosystem.