Population estimates, nesting biology, and habitat preferences of Interlake, Manitoba, Sandhill Cranes, Grus canadensis

Abstract

We found breeding Sandhill Cranes at 86 sites in the Interlake region of central Manitoba between 1977 and 1980. In 1979 we found 54 pairs in a 4250 km2 portion of our study area. This density of 1.3 pairs per 100 km2 is the lowest reported for Sandhill Cranes in boreal and arctic North America. Over 400 additional cranes were present as nonbreeders in 1979. Of a sample of 32 nests, 17 occurred on "islands" or raised hummocks dominated by woody vegetation, and 15 occurred in herbaceous emergent vegetation. Mean clutch size was 1.89. Hatching began during the last week of May and continued into June. Forty-seven of 51 (92%) nests occurred in fen muskegs, as did 91 of 106 (86%) observations of crane families with chicks. These precentages were significantly higher than expected based on known acreages of fen and bog muskegs, forested muskegs, and mineral soils in the study area. Fen muskegs may be selected over bog muskegs because of the former's higher productivity. Fen peatlands may be predictors of the distribution and relative abundance of breeding Sandhill Cranes elsewhere in central Canada.