Dowling Lake (AB025)
Hanna, Alberta
Description du site
Dowling Lake is located roughly 8 km northwest of Hanna, Alberta in the southcentral part of the province. Wetland complexes, consisting of ephemeral marshes, wet meadows and alkali marshes surround this large, 30 km² alkali lake. Dowling Lake is fed by Wolf Creek and by alkaline springs, but there is no outflow from the lake. The substrate along the shoreline consists of gravel and mud.
Oiseaux
Piping Plovers (nationally endangered, globally vulnerable) are found in significant numbers at this site. In 1996, 54 birds were recorded, while over the last thirty years, the number of breeding Piping Plovers has ranged from zero to 58, generally with higher numbers recorded in more recent years. The average number of Piping Plovers recorded over four surveys between 1986 and 1996 was 32 (representing about 1% of the estimated Northern Great Plains population and 2% of the estimated Canadian Great Plains population. The variations in plover numbers are in large part reflective of water level fluctuations. Much of the Piping Plover habitat is on the east shore, with some suitable habitat occurring on the northwest shore.
Dowling Lake is also significant for colonial waterbirds and concentrations of staging waterfowl. Estimates of staging geese range from 5,000 to 15,000. Although recent surveys have not been completed, as many as 5,184 Ring-billed Gulls nests and 824 California Gull nests were recorded at this site in 1976. Other colonial waterbirds include Double-crested Cormorants (fewer than 500 pairs), Great Blue Herons (fewer than 30 pairs) and Common Terns (fewer than 100 pairs). The present status of these breeding birds is not known, although none were recorded from 1987 to 1996.
Shorebirds are sometimes present in large numbers when the conditions are right. Also, the grasslands surrounding the lake contain good habitat for Bairds Sparrows and Spragues Pipits.
Enjeux de conservation
Dowling Lake is a shallow body of water that is quite susceptible to drought and therefore naturally rising and falling water levels. Stabilization of water levels would not be desirable, since plover habitat is partly created by fluctuating water levels. Trampling by cattle (which use the lake as a water source), disturbance by off-road vehicles, and the encroachment of shoreline vegetation are all potential threats to the nesting Piping Plovers at this site.
Dowling Lake has been identified as a potential Western Hemisphere Shorebird Reserve Network (WHSRN) site under the endangered species category.
Catégories ZICO Habitats Usages Menaces Potencielles ou Existantes Status de Protection
