Decline of wildcelery buds in the lower Detroit River, 1950-85

American wildcelery buds (Vallisneria americana), an abundant food eaten by diving ducks (Aythini) during migrations, decreased in the lower Detroit River of the Great Lakes from 1950 to 1985. Bud densities decreased at 2 (- 14 and - 18 buds/m2) of 5 locations and were similar at 3 (-2, +2, and +3 buds/m2) of 5 locations. Net change in all 5 areas combined, however, was a decrease of 36,720,000 buds, a 72% decline. Estimated potential losses of waterfowl feeding days caused by the decreased bud densities were 147,000 for canvasbacks (Aythya valisineria), 241,000 for redhead ducks (A. americana), or 664,000 for lesser scaup (A. affinis). Thus, the decline of wildcelery in the Detroit River may have contributed to decreased use of Michigan migration routes by some waterfowl species between 1950 and 1985.