The Sand Reef Islands of Lake Manitoba are located to the east of Ducharme Island, and to the west of Duck Island (also known as Big Birch Island). The IBA additionally includes those islands that are roughly midway between the Sand Reef Islands and Mathews Point. Alonsa is the closest major town, located to the southwest, but the hamlet of Vogar, to the northeast, is nearer to this site. The islands are extremely low-lying with a limited amount of relief and consequently they are subjected to flooding during periods of high water and heavy winds.
Based on a Northern American estimated total of only about 34,000 pairs of Caspian Terns, the low-lying islands of this site are home to minimally 3% (1,000 nests recorded) of this population. An unsubstantiated (and possibly erroneous) report records an impressive 3,400 pairs occurring here. Caspian Terns, formerly designated as rare in Canada, have recently been de-listed by the Committee on the Status of Endangered Wildlife in Canada.
An extensive waterbird breeding survey was completed at this site in 1986. In addition to the Caspian Terns, a total of 300 Common Tern nests, 750 Ring-billed Gull nests, 250 Double-crested Cormorant nests, and 220 American White Pelican nests were recorded on the islands.
There are relatively few threats to this IBA. Occasionally, severe wind tides flood sections of the islands, sometimes inundating low-lying bird's nests leading to reduced recruitment and productivity. These islands are owned by the crown.IBA Criteria Habitats Land Uses Potential or Ongoing Threats Conservation Status