Red-winged Blackbirds are a very common bird species found throughout much of North and Central America. They are one of the most abundant and widespread birds on the continent. While they may seem ubiquitous in many areas, their populations have undergone changes over time that provide insight into how rare or common they truly are.
Range and Population
The Red-winged Blackbird has an extremely large range across North and Central America. According to the Cornell Lab of Ornithology, their breeding range covers Alaska and Canada down throughout the continental United States south to Panama. Population densities are highest in the northern Great Plains, eastern North America, coastal areas of the Southeastern U.S., and parts of Mexico.
The current global population of Red-winged Blackbirds is estimated to be somewhere between 100-200 million individuals. In North America alone, population estimates range from 80-190 million birds. They are considered to be one of the most abundant bird species on the continent.
Within their widespread range, Red-winged Blackbirds can be found in a variety of wetland habitats during the breeding season, including:
- Marshes
- Swamps
- Ponds
- Lakeshores
- River Edges
- Agricultural Fields
They tend to favor areas with dense stands of cattails and other aquatic vegetation. During the winter they can be found in more open areas including agricultural fields, pastures, roadsides, grasslands, and along the coast.
Population Changes
Although Red-winged Blackbirds remain extremely abundant, data from the North American Breeding Bird Survey has shown populations declining by an estimated 58% between 1966-2015. However, trends have varied regionally.
The table below summarizes population trends by region:
Region | 1966-2015 Trend |
---|---|
Eastern Breeding Bird Survey Region | -2.2% per year |
Central Breeding Bird Survey Region | -3.5% per year |
Western Breeding Bird Survey Region | -3.9% per year |
All Regions | -3.7% per year |
The steepest declines have occurred in the Prairie Pothole region of northcentral U.S. and southcentral Canada. However, populations have increased in some northern areas during the same period.
Multiple factors may be contributing to these changes including:
- Wetland drainage and habitat loss
- Pesticide use
- Climate change
- Disease
- Competition from European Starlings
Conservation Status
Despite population declines, the IUCN Red List categorizes the Red-winged Blackbird as a species of Least Concern. Their huge range and large population size provide resilience against threats. As one of the most studied bird species on the continent, Red-winged Blackbirds serve as an indicator of environmental health. Ongoing monitoring and habitat management will be important for their long-term conservation.
Rarity Within Range
Red-winged Blackbirds are considered common to abundant throughout most of their range. Their vast numbers stand out and they often represent a high percentage of birds within their habitat. However, there are some regions where they are less numerous:
- Along the Pacific Coast they are rare west of the Cascade Mountains and other coastal mountain ranges.
- In western Canada their breeding range extends to central British Columbia but they are scarce west of the Rocky Mountains.
- They are locally less common in the arid southwestern U.S.
At more local scales, Red-winged Blackbird abundance can vary greatly based on habitat. They may be scarce or absent in drier areas without suitable wetlands. But anywhere with adequate aquatic vegetation and nearby agricultural fields, they can reach remarkably high densities.
Seasonal Changes in Abundance
The abundance of Red-winged Blackbirds also changes throughout the year as populations shift. They are considered migratory over most of the northern and central portions of their range. However, southern populations may not migrate.
During the breeding season, millions nest across North America with densities highest on the breeding grounds. They congregate in huge migratory flocks of hundreds of thousands to millions of birds in fall. They gradually disperse farther south with some migrating as far as Central America. Winter populations in the southern U.S. and Mexico boom as migrants arrive.
By spring, populations transition back northward to breeding areas. The cycle then repeats annually. So at a local level, Red-winged Blackbird abundance depends greatly on seasonal timing and location relative to their migratory patterns.
Rarity Within Habitats
The abundance of Red-winged Blackbirds also varies depending on habitat type. As wetland specialists, they reach maximum densities in marshes with an interspersion of emergent vegetation and open water. Deep water marshes with expansive cattail stands and wet meadows represent prime breeding habitat.
According to Audubon’s climate model, ideal summer range consists of:
- At least 30% wetland cover
- 30% or more herbaceous/grassland cover
- 30% open water
Within these optimal wetlands, Red-winged Blackbird densities may exceed 2,000-3,000 breeding pairs per 100 acres in the Prairie Pothole Region. Compared to any other area, these densities classify the birds as common to abundant.
As conditions become drier, the birds become more localized and less common. Upland areas and wooded wetlands generally support lower densities. Croplands and pasturelands may contain breeding birds where wetlands are nearby, but their prevalence drops off rapidly in purely upland habitats. So their abundance has a strong association with wetland habitat quality and availability.
Rarity Within Regions
Across their range, Red-winged Blackbirds reach peak densities in the Prairie Pothole Region of the Great Plains. This area contains millions of small wetlands perfect for breeding. Densities are also high across much of the Midwest, Great Lakes region, and portions of eastern Canada where wetland habitat is abundant.
Within the Prairie Pothole Region, numbers peak in North Dakota and northwest Minnesota which contains prime wetland habitat. Very high densities also occur in Iowa, South Dakota, and southeast Saskatchewan.
Regional abundance drops off toward the east and west in less ideal habitat. Densities are lower in the drier western edge of their range as well as western forests. Along the Atlantic Coast and Gulf Coast populations are scattered and localized.
So while still common, Red-winged Blackbirds reach their greatest abundance in the central portions of their range where habitat is optimal and most available.
Historical Abundance
Historically, Red-winged Blackbirds were even more abundant across North America before modern settlement. Early European explorers and pioneers consistently described them as very numerous.
It is estimated that there were around 22 million acres of prairie pothole wetlands prior to the mid-1800s. With the vast majority of these high quality wetlands, the Red-winged Blackbird population would have been proportionally higher.
As forests were cleared and marshes drained for agriculture, their ideal habitat declined. Populations likely peaked in the early 1800s or mid-1800s before steep reductions occurred. Despite habitat losses, they remain well-adapted and widespread across the modern landscape.
Rarity on Christmas Bird Counts
The Christmas Bird Count (CBC) conducted annually by Audubon provides another metric to evaluate Red-winged Blackbird abundance. During the 2019-2020 CBC:
- Red-winged Blackbirds were detected on 99% of counts
- They were the 5th most frequently observed species
- Nearly 2.1 million individuals were counted
This makes Red-winged Blackbirds one of the most widespread and commonly recorded species on the CBC each year. Their huge winter populations descend on fields and wetlands across much of North America.
However, Red-winged Blackbirds do become scarce on CBC circles along the West Coast and in the extreme Southeastern U.S beyond their typical winter range. Their numbers also thin out in western and northern areas with significant winter snow cover.
Rarity at Bird Feeders
One place Red-winged Blackbirds are rarely found is at backyard bird feeders. Their diet consists mainly of seeds from moist soil, grasses, sedges, grains, fruits, and insects. They do little feeding at bird feeders.
However, during winter months Red-wings will occasionally visit platform feeders or ground feeders for various seeds. Backyard sightings increase on migration as flocks stop to feed. But overall, this is not a common behavior and they are uncommonly seen at feeders compared to other species.
Legal Protections
Red-winged Blackbirds are classified as migratory birds protected under the Migratory Bird Treaty Act of 1918. This makes it illegal to harm, harass, or kill Red-winged Blackbirds without a permit. Their nests and eggs are also protected from being destroyed or taken.
No additional state-level or federal protections apply to Red-winged Blackbirds since they remain a widespread, common species. Protections allow them to be legally hunted during waterfowl hunting seasons under certain regulations.
Significance of Red-winged Blackbird Rarity
In locations where Red-winged Blackbirds are rare, it usually indicates issues with habitat availability. Loss of wetlands in an area generally corresponds with lower densities. Their numbers provide an important gauge of ecosystem health.
A lack of Red-winged Blackbirds also suggests fewer prey sources and decreased nesting habitat for predatory hawks, owls, snakes, and other wildlife. Absence of this keystone species has cascading effects across food chains.
Where Red-winged Blackbird populations are stable or increasing, it demonstrates there is sufficient wetland habitat available. Land managers in areas with declines can look to reverse the trend through wetland restoration and protection to support higher densities.
Conclusion
In conclusion, Red-winged Blackbirds remain one of the most numerous and widespread bird species found in North America. Tens of millions breed across the United States and southern Canada each year. However, declines in portions of their range indicate populations are not as large as they once were historically.
Regionally, Red-winged Blackbirds reach peak abundance in the Prairie Pothole wetlands where habitat is ideal. They are least common along the Pacific Coast and parts of the arid Southwest. At more local scales, the quality of wetland habitat directly determines density and rarity. They are scarce in drier uplands away from marshes.
While still common, ongoing monitoring of Red-winged Blackbird populations provides an important indicator of ecosystem health. Maintaining wetland habitat across North America will be key to ensuring these iconic blackbirds remain a familiar sight and sound each summer. Their vast numbers and ubiquity in suitable habitat make declines in local density more noticeable as a warning sign of habitat loss.