| IBA |
Riverton Sandy Bar
Riverton, Manitoba |
| Site Summary |
| MB091 |
Latitude
Longitude |
51.005° N
96.890° W |
Elevation
Size |
218 m
18.24 km² |
Habitats:
freshwater lake, other
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Land Use:
Nature conservation and research, Fisheries/aquaculture, Hunting, Tourism/recreation
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Potential or ongoing Threats:
Disturbance, Recreation/tourism
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| IBA Criteria: Globally Significant: Congregatory Species, Colonial Waterbirds/Seabird Concentrations |
| Conservation status: IBA Conservation Plan written/being written |
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Site Description
The IBA consists of two sandbars jutting out into the channel between the western shore of Lake Winnipeg and Hecla Islands. The Riverton sandbar is situated to the east of the community of Riverton and an adjoining marsh, extending eastward toward the Sand Point sandbar on Hecla Island. In years when lake levels are high, the sandbars flood and this has the effect of creating three islands on the Riverton sandbar, the closest being 50 metres from the mainland. The sandbars are comprised of sand and gravel that has been partially colonized by grasses and willows.
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Birds
This site supports significant concentrations of Ring-billed Gulls and Common Terns. About 0.78% (10,000 nests) of the world's estimated Ring-billed Gull population were present in 1991. In addition, a total of 800 Common Tern nests were recorded in the same year. Nesting Herring Gulls were also present, with 153 nests being recorded in 1991. The Sand Point on Hecla Island is also noted as a major roost site for American White Pelicans (481 in 2016), Double-crested Cormorants (500 in 2014), gulls and terns.
There are also occasional records of nesting Piping Plovers (nationally endangered and globally near-threatened) on the Riverton Sand Islands and on the adjacent Hecla Island Sand Point. During the 1991 International Piping Plover census one pair of Piping Plovers was recorded at each site, while during the 1996 International census only a single pair of Piping Plovers was recorded at the Hecla Island Sand Point. The last confirmed sighting was in 2000.
In addition to the importance of these islands and sandspits to nesting birds, they are also heavily used by several species during migration. The wider area is reportedly a major site for migrating Canada Geese and Snow Geese. The site has also become known locally for migrating shorebirds from the High Arctic, boreal ecozone and Hudson’s Bay Lowlands including records of Ruddy Turnstone, Sanderling, Red Knot, Semipalmated Sandpiper, Black-bellied Plover, American Golden Plover and Buff-breasted Sandpiper. Previous reports have indicated that hundreds of migrating Sanderling use the site, although this has never been verified. Rusty Blackbirds also arrive in good numbers in late fall along with Lapland Longspur, Smith’s Longspur, Snow Bunting, Horned Lark and American Pipit.
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IBA Criteria |
| Species↓ T | A | I |
Links |
Date |
Season |
Number |
G |
C |
N |
| Ring-billed Gull |
|
1991 |
SU |
20,000 |
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| Rusty Blackbird |
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2014 - 2016 |
FA |
38 - 50 |
✔ |
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Note: species shown in bold indicate that the maximum number exceeds at least one of the IBA thresholds (sub-regional, regional or global). The site may still not qualify for that level of IBA if the maximum number reflects an exceptional or historical occurrence.
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Conservation Issues
Sand Point on Hecla Island is part of the Hecla/Grindstone Provincial Park and due to its relative isolation sees little in the way of recreational disturbance. The Riverton Sandbar was designated as a Special Conservation Area in 2014 by Manitoba Sustainable Development due to its historic significance for Piping Plover. The designation will ban the use of all-terrain vehicle (ATV) from April 1st through to September 15th and restrict access if Piping Plover breed here in future years.
The continued suitability of these islands for nesting colonial waterbirds depends on the suitability of habitat conditions and low levels of recreational disturbance. Important natural forces include water currents, and ice scouring, which removes colonizing vegetation. During years when water levels are low, ATVs can gain full access to the Riverton sandbar leading to the strong possibility that nests are abandoned due to repeated disturbance. There may also be increased access by mammalian predators during these low water years. In most years, however, the water levels are deep enough to prevent this from happening. The artificially high water levels that are maintained by Manitoba Hydro, however, lead to less shoreline for the Piping Plovers and increased erosion. In combination with low water levels, this increased erosion (possibly also caused by ATV tracks), has led to increased encroachment by invasive plants, especially white sweet clover. These colonizing plants reduce the area of habitat available not just for Piping Plover but also other nesting birds. Recent efforts are being made to combat this issue via weed pulling work parties.
There is also some desire to develop this site for ecotourism, which could increase the level of disturbance, but might also lead to more vigilant protection.
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