• Summary
• Text account
• Data table and detailed info
• Map
• Reference and further resources

Site description (2001 baseline)
Big Muddy Lake is a large saline lake in the semi-arid region of southern Saskatchewan. It is located about 24 km south of the town of Bengough and 12 km north of the Montana border. Situated in the rugged Big Muddy Valley, the lake was once part of a great river that flowed out of a glacial lake in the Old Wives Lake area south to the Missouri River in Montana. The lake is mostly filled by the Big Muddy Creek at the northwest end, but dozens of intermittent creeks also run into the lake through eroded coulees. This region contains a wide variety of habitats that include alkaline flats, marshy creeks and springs, steep eroded cliffs with exposed rock outcrops, undulating and rolling prairie uplands, heavily wooded draws, sage flats and some cropland. A large co-operatively owned pasture borders a portion of the west shore of the lake.

The Eastern Yellow-bellied Racer and the Smooth Greensnake are two reptiles found here that are at the northern limit of their range. Also, several plants that are unusual for southern Saskatchewan have been recorded: Purple Cliff Brake, Linear-leaved Umbrellawort, and Oregon Woodsia.

Key biodiversity
The lakeshore supports a large and important Piping Plover population. The Piping Plover is considered vulnerable on a global scale and has been designated as endangered in Canada. The 1996 International Piping Plover Survey recorded 1,687 birds in the Canadian Prairies and 4,226 additional birds throughout the rest of North America. Between 1986 and 1996 an average of 21 plovers (1.1% of the Canadian prairie population) have been recorded at Big Muddy Lake with a high of 34 (2%) in 1996. This average is based on variable numbers that have been highest during the most recent survey years. The lake also supports as many as 5,000 ducks that congregate here in the fall and during the summer moulting period.

The mixed habitats surrounding the lake support rich communities of land birds, particularly raptors. The badlands here support some of the highest concentrations of breeding Golden Eagles, Prairie Falcons and Turkey Vultures in the province. Six Prairie Falcon nest sites are also known (2.4% of the Canadian population), although not all are used every year. Two nesting sites of the nationally vulnerable Ferruginous Hawk and two nesting sites of the nationally endangered Burrowing Owl are also present.

The nationally endangered Sage Thrasher has also been observed once during the breeding season, suggesting that nesting by this species is possible in the sage flats. Since the Canadian population is estimated to be only 5 to 22 pairs, even a single pair would be significant. The badlands and wooded coulees provide habitat for several regionally uncommon species such as Violet-green Swallow, Rock Wren, Veery, Ovenbird, Baltimore Oriole, and Spotted Towhee.

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Recommended citation
BirdLife International (2025) Important Bird Area factsheet: Big Muddy Lake (and surroundings) (Canada). Downloaded from https://datazone.birdlife.org/site/factsheet/big-muddy-lake-(and-surroundings)-iba-canada on 01/01/2025.