The Pipestone Rocks are a group of small islands in the southern portion of Lake Winnipeg, Manitoba. They are located near the northern edge of the Hecla / Grindstone Provincial Park; Deer Island is located directly to the south, and Grindstone Point is located to the southwest. The islands, which are comprised of granite rock extrusions filled with bird guano, are devoid of trees and shrubs. The water level around the island can change greatly due to the wind tides that occur on Lake Winnipeg. Since water levels fluctuate greatly from year to year, the size and shape of the islands often changes. During high water years the islands may completely disappear.
Large numbers of American White Pelicans nest on the Pipestone Rocks. During a 1997 survey there were at least 500 pairs of American White Pelicans present (a thorough survey was not completed because observers did not want to unduly disturb the birds). A 1990 survey also recorded large numbers, with 713 American White Pelican young being observed. This likely represented about 1,500 adults. Based on these surveys, it appears that about 1% of the estimated national population of American White Pelican regularly nests at this site.
Other species that nest on these islands include: Herring Gulls (275 pairs in 1990), Ring-billed Gulls (>2,000 nests), and Double-crested Cormorants (over 500 pairs in 1990).
BirdLife International (2021) Important Bird Areas factsheet: Pipestone Rocks. Downloaded from http://www.birdlife.org on 29/11/2021.