Statement on Drought Conditions During the Saskatchewan Breeding Bird Atlas
The temperate grasslands that span the southern portions of Canada’s Prairie Provinces experience low to moderate annual precipitation that impedes the establishment and growth of woody shrubs and trees to varying degrees, and results in ecoregions that are dominated by grasses and herbaceous plants. The region experiences high annual variability in precipitation in time and space as well as annual extremes in temperature which result in regular wet-dry cycles throughout the region. Variability in precipitation inputs can cause both short-duration (months to seasons) or long-duration (multi-year) droughts that are not typical of other regions of Canada. This wet-dry cycle is important to maintaining landscape characteristics because dry periods further impede the growth of woody plants, and they rejuvenate prairie pothole wetlands by exposing organic matter to aerobic decay which makes nutrients more available when the next wet period occurs.
During prolonged dry periods large numbers of seasonal wetlands dry up, sometimes for years at a time, and when dry, the basins fail to attract waterfowl, waterbirds, and other wetland-associated species that are typically present when the basins contain water. Hydrologic conditions in the prairie and parkland ecoregions in southern Saskatchewan during the years of Atlas data collection (2017-2021) were characteristic of drought. During all years, some portion, or the entirety of the prairie and parkland ecoregions experienced drought conditions that ranged from abnormally dry, to moderate drought, to severe drought, extreme drought, and occasionally exceptional drought. See the maps below for May-July drought conditions for each year of the atlas. Additional monthly maps from the Canadian Drought Monitor can be found for 2007 onward here.
Different species of waterfowl, waterbirds, and other wetland-associated species select breeding locations based on a variety of habitat conditions but water is the dominant prerequisite for suitable breeding habitat. Some species nest within the emergent vegetation (e.g., coots, Marsh Wrens, diving ducks) or on floating mats of vegetation (e.g., Black Terns) and these species spend most of their time within wetlands, while other species will select upland habitat for nest sites (e.g., dabbling ducks) that are in proximity of wetlands and then use the wetland habitat for foraging and brood rearing. When wetland basins are dry, they cannot support the primary habitat requirement of water-loving birds, so drought conditions can have a marked effect on the distribution and number of wetland-associated species across the landscape.
During all years of the Saskatchewan Breeding Bird Atlas drought conditions persisted and the Atlas range maps for all waterfowl, waterbirds, and wetland-associated species should be viewed as characteristic of distribution and abundance during dry conditions.
