Delta Marsh is a large wetland comprised of wide shallow bays, sloughs and meadows. It stretches westward from St Laurent to Lynch Point along the southern end of Lake Manitoba. The marsh is separated from the lake by a sand ridge covered with deciduous trees including green ash, Manitoba maple, hackberry, willow and cottonwood. The hackberry stand is the northernmost location for this species within Manitoba. The ridge and associated deciduous forest acts as a natural migrational corridor for landbirds migrating to and from the boreal forest and aspen parklands to the west of Lake Manitoba. The 17,000 ha marsh is one of the largest of several marshes in the Lake Manitoba basin.
Large numbers of both diving (Canvasback, Redhead, Lesser Scaup) and dabbling (Mallard, Gadwall, American Wigeon, and Northern Pintail) ducks stage in the marsh each fall. Up to 100,000 waterfowl have been detected during aerial surveys (no aerial surveys have been completed since 1991). The number of geese using the site has increased from historic levels with Canada Geese and Snow Geese staging here in large numbers during both spring and fall migration. Ruddy Turnstones congregate in large numbers, such as 1,000, on June 2, 1993.
Large numbers of landbirds also make use of the site. Some indication of the significance is reflected in the banding totals reported by the Delta Marsh Bird Observatory. Between 1995 and 1997, the number of landbirds banded in a single season ranged from 7,500 to more than 9,000 individuals suggesting even higher (much higher) totals of birds migrating through or breeding in the area. In 1996, a total of 3,000 Yellow Warblers and 1,100 Tennessee Warblers were banded. More than 300 individuals of several other landbird species (Yellow-rumped Warbler, American Redstart, White-throated Sparrow, Least Flycatcher, Ruby-crowned Kinglet, Common Yellowthroat, and Song Sparrow) are also regularly banded each season. Up to 50,000 Tree and Bank swallows have been estimated during daily censuses.
Concentrations of over 1000 Western Grebes during migration (1996) and over 1000 pairs breeding (1979), and over 1000 Franklin Gulls have also been observed.
BirdLife International (2020) Important Bird Areas factsheet: Delta Marsh. Downloaded from http://www.birdlife.org on 26/09/2020.