Effects of Wetland Creation on Breeding Season Bird Use in Boreal Eastern Ontario

Wetland construction has been an effective means of mitigating wetland habitat losses due to agricultural and other activities. However, the type, variety, and age of the habitats created are often critical components in the success of the wetland when the aim is to enhance the bird community. Hilliardton Marsh was constructed as a series of cells between 1993 and 1997 in boreal eastern Ontario to provide waterfowl habitat. We determined habitat change and monitored breeding-season bird use before construction and one year after the last cell was constructed. Wetland construction resulted in dramatic changes to the vegetation and bird communities. The area was transformed into a variety of wetland habitats, but primarily marsh, one of the rarest wetland types in boreal Ontario. Survey stations with moderate habitat change exhibited the greatest change in bird species richness. Total species richness increased 55% from 56 to 87 species, with obligate wetland birds increasing from 3 to 26 species. Rare birds increased from 11 to 27 species, with most as obligate or facultative wetland birds, but also Peregrine Falcon (Falco peregrinus). Bird abundance, as measured by the number of stations where a species was observed, increased significantly for obligate wetland birds. There were no significant losses of species from any bird group, as adjacent upland habitat was preserved. This short-term study has shown that construction of new wetland habitat in boreal eastern Ontario, especially marsh, can significantly increase the numbers of breeding-season birds, including rare species. However, longterm monitoring is required to ensure sustained success of wetland construction projects for birds