Netley-Libau Marsh is situated at the south end of Lake Winnipeg, where the Red River branches several times and empties into the lake. Wave action on Lake Winnipeg, particularly due to strong wind-assisted tides, has produced a small beach ridge at the lakes south end, which acts as a barrier separating parts of Netley-Libau Marsh from the lake. The Red River is an important force of change in the large network of wetlands found here. Due to its history of frequent flooding, the route of the main channel of the river has changed numerous times. The area is very flat, and consists of many small bodies of water connected by channels and is interlaced with fingers of grassland, trees and shrubs.
Netley-Libau Marsh is best known for its tremendous concentrations of southward-migrating birds. Numbers of geese and ducks on some occasions exceed 100,000 during fall migration. A little earlier in the year, at least 25,000 moulting ducks are found in the area. Red-winged and Yellow-headed blackbirds congregate here in late autumn in numbers exceeding 100,000. As well, at the beginning of the fall migration in August, swallows are found here in the thousands.
In addition to the numerous species that stopover at the site during fall migration, several bird species breed at this site in significant numbers. Franklins Gulls nest in large colonies within the marsh, in numbers exceeding 4,500 pairs. This represents at least 1.3% of the North American population, based on upper level population estimates. In the late 1970s, 325 Forsters Tern nests were recorded in the marsh (about 1.5% of the global population). In addition, over 100 pairs of Black-crowned Night-Herons have been observed nesting in the marsh, which account for 2% of the estimated national population. Species that breed in large, though not significant numbers at the site include the Eared Grebe (100+ pairs) and the Western Grebe (125+ pairs). At least twelve species of ducks breed here mostly dabbling ducks.
BirdLife International (2020) Important Bird Areas factsheet: Netley-Libau Marsh. Downloaded from http://www.birdlife.org on 30/09/2020.