The blue-winged teal (Spatula discors) is a small dabbling duck found in North America. They are highly migratory birds, breeding in the Prairie Pothole Region of the United States and Canada before migrating to wintering grounds in the Southern United States, Mexico, Central America, and the Caribbean. Knowing where blue-winged teals breed can provide important information about their habitat needs and population dynamics.
Breeding Range
Blue-winged teals breed primarily in the Prairie Pothole Region, which encompasses parts of Alberta, Saskatchewan, Manitoba, Montana, North Dakota, South Dakota, Minnesota, and Iowa. This landscape was formed by glaciers and contains millions of small, shallow wetlands known as potholes that provide ideal breeding habitat for blue-winged teals and other waterfowl species.
Specifically, the core breeding range extends across central Saskatchewan through southern Manitoba, central North Dakota and South Dakota, western Minnesota, and northwestern Iowa. The species also breeds locally elsewhere in the Prairie Provinces, northern Great Plains, western Great Lakes region, and southern Ontario.
Blue-winged teals prefer small, shallow wetlands for breeding – generally seasonal or semi-permanent wetlands under 5 acres in size and less than 3 feet deep. These small potholes warm faster in spring, allowing for earlier nesting and better duckling survival compared to larger, deeper wetlands.
Habitat Preferences
Blue-winged teals exhibit preferences for certain habitat characteristics when selecting breeding sites:
Wetland Type: Shallow, seasonally flooded basins and wet meadow zones of wetlands with stable water levels and abundant emergent vegetation. Avoid deeper semi-permanent or permanent wetlands.
Water Depth: Less than 1 foot deep. Avoid deeper open water.
Vegetation: Prefer dense stands of emergent vegetation, such as cattails, bulrushes, and sedges. Vegetation provides nesting cover and habitat for invertebrate foods.
Abundant Invertebrates: Crucial for egg production and duckling survival. Wetlands with abundant aquatic invertebrates like insects, mollusks, and crustaceans are favored.
Adjacent Uplands: Look for wetlands near upland nesting cover like dense grasslands or hayfields. Uplands provide nesting habitat.
Ideal wetlands have shallow marsh zones rich in emergent vegetation and invertebrates, surrounded by upland nesting cover. These habitats provide food, shelter, and nest sites.
Most Favored Habitats
The following wetland habitats typically provide prime blue-winged teal breeding habitat across their range:
- Prairie pothole wetlands
- Wet meadow zones within wetland complexes
- Flooded agricultural fields
- Shallow marsh and wetland edges
- Narrow wetland fringes along small streams
Nesting
Female blue-winged teals build nests on the ground in dense vegetation near water. Nests are bowls lined with down and vegetation that conceal the eggs. Preferred nest sites include:
- Upland grasslands and hayfields – provides overhead concealment
- Wetland edges – allows easy water access
- Under shrubs or other dense, low vegetation
- Along streams or drainage channels
Nests are usually located within 100 meters of water but may be over 1 kilometer away in some cases. The female alone incubates the 8-10 cream-colored eggs for 21-27 days. Ducklings hatch in early summer and are led by the female to adjacent wetlands where they feed on aquatic invertebrates.
Breeding Chronology
Spring Migration
Blue-winged teals begin migrating north from southern wintering grounds in February and March. Early arrivals reach the southern edge of the breeding range by late February. Birds continue to arrive on the breeding grounds through April.
Pair Formation and Courtship
Most blue-winged teals form pairs during spring migration or shortly after arriving on breeding areas. Courtship displays commence in March and involve elaborate rituals like head pumping, grunt whistles, and ritualized swims. Males also perform aerial displays. Females assess male fitness during courtship.
Nest Initiation
Nesting starts in April but peaks in May and early June. Timing depends on wetland conditions – nesting is delayed in cold springs or when wetlands are frozen. Early nesting matched with mild weather allows for faster duckling growth and better survival.
Incubation and Hatching
Incubation lasts 21-27 days. Most eggs hatch by mid-June. Later nesting may extend into July. The timing of hatching coincides with peak aquatic invertebrate abundance which is crucial for duckling survival.
Brood-rearing
Ducklings remain with the female parent for 25-40 days after hatching. Broods feed heavily on protein-rich aquatic invertebrates for rapid growth. Wetlands that provide abundant insect larvae, mollusks, and crustaceans are essential for brooding.
Fall Migration
Blue-winged teals start migrating south in September. Northern breeders are typically gone by October. Migration continues through November with most birds reaching wintering grounds by December.
Population Status and Threats
Blue-winged teal numbers reached historic lows in the 1970s but increased after conservation efforts improved breeding habitat. They remain one of the most abundant ducks in North America. However, habitat loss, pollution, and climate change pose long-term threats.
Population Trend:
- 1966: 3.5 million
- 1979: 1.8 million (historic low)
- 2015: 7.3 million
Threats:
- Drainage and degradation of prairie pothole wetlands
- Conversion of grasslands to agriculture
- Wetland contamination from industrial/agricultural runoff
- Increasing frequency of drought that dries wetlands
- Predation on nests and ducklings
Protecting prairie potholes will be key for the continued success of blue-winged teal populations. Management should focus on acquiring and restoring wetland and grassland habitat across the breeding range.
Conclusion
In summary, blue-winged teals are strongly tied to the Prairie Pothole Region of northcentral North America for breeding. They favor shallow, vegetated wetlands and adjacent upland nesting cover. Nesting starts in April-May, and most eggs hatch by mid-June. Ducks concentrate on wetlands rich in invertebrate foods to fuel rapid duckling growth. While populations recovered from historic lows, continued wetland conservation will be needed to offset ongoing habitat losses. Understanding their breeding ecology and habitat needs is key for effective management.