The effects of river flow augmentation on the channel form, vegetation, and riparian birds of the Little Bow River, Alberta

Globally, river systems have been regulated, reducing flows through diversions of water for societal use. In rarer scenarios, augmentation of flows may be undertaken, generally to convey water for irrigation agriculture. The Little Bow River, a small, historically intermittent river in southern Alberta, experienced a tripling of flows in 2004. Channel restructuring, vegetation transitions favouring riparian specialist species, and increasing avian community biodiversity were anticipated. Analysis of aerial photographs from 1967 to 2010 indicated restructuring of river channels as widths increased between 2000 and 2010, and vegetation showed signs of transitioning with declines in graminoid communities. Avian community surveys indicated an increase in species richness, comparable species evenness and Shannon Wiener Index, and recovering yellow-headed blackbird populations in response to changing habitat structure. Land-use management, limited augmentation, and a short timespan delayed anticipated responses along this system, requiring continued monitoring in the future.