The yellow-winged blackbird (Agelaius thilius) is a species of bird found in South America. They are medium-sized blackbirds with bright yellow shoulder patches on their wings. Yellow-winged blackbirds are social birds that live in large flocks and nest colonially. Their populations are generally stable and they are classified as a species of Least Concern by the IUCN Red List. However, some local populations have declined due to habitat loss and degradation. The rarity of yellow-winged blackbirds can vary by region.
Are Yellow-Winged Blackbirds Rare Overall?
Yellow-winged blackbirds have a widespread distribution across South America and are found in a variety of habitats including marshes, grasslands, agricultural areas, and urban parks. Their total global population is estimated to be 5-50 million individuals. This indicates that they are a relatively abundant species overall. However, in some parts of their range, yellow-winged blackbird populations have declined and could be considered locally rare. But on a continental scale, they remain common and widespread.
Population Status by Country
Brazil
Yellow-winged blackbirds are found across many regions of Brazil. They are described as an abundant resident throughout their Brazilian range. Population trends appear to be stable and they are not considered threatened or rare in the country.
Argentina
This species is common and widespread in suitable habitat across Argentina. They are described as locally abundant in the Buenos Aires region and are common in grasslands and wetlands further south. Populations appear stable across most of the country. They are not considered rare or threatened in Argentina.
Bolivia
In Bolivia, yellow-winged blackbirds occur widely across the northern and central parts of the country. They can be found in large flocks around marshes and rice fields. Within their Bolivian range, this species is common and populations remain stable. There is no evidence that they are rare or declining in Bolivia.
Paraguay
The yellow-winged blackbird has been reported as a locally common species in Paraguay. It is found in wetlands and grassy areas from the Pantanal region to the Parana River. There are no major threats to the species in Paraguay and its numbers are thought to be steady. It is not considered a rare bird in this country.
Peru
In Peru, yellow-winged blackbirds occur along the northern coast and Amazon basin. They are described as being fairly common in open wetlands throughout their Peruvian range. There are no reports of major population declines and the species seems to be doing well, indicating it is not rare here.
Uruguay
This species is a common resident of wet grasslands and marshes in Uruguay. It has a widespread distribution throughout the country. Yellow-winged blackbird populations appear to be stable and healthy in Uruguay, where it is not considered rare or threatened.
Venezuela
In Venezuela, the yellow-winged blackbird is found across the northern and western regions of the country. It is described as a very common species in the Llanos grasslands and marshy areas of the coast. Venezuela is thought to host large, stable populations of this blackbird. There are no signs it is rare in any part of its Venezuelan range.
Colombia
This species occurs in suitable habitat on the northern coast and eastern plains of Colombia. It is considered a fairly common resident throughout its Colombian range. Populations do not appear to be declining significantly. The yellow-winged blackbird remains common and widespread in Colombia and is not rare.
Ecuador
In Ecuador, the yellow-winged blackbird inhabits coastal wetlands and grasslands in the western part of the country. It has been recorded as locally common and the population is presumed to be stable. There are no reports of major declines or rarity for this species in Ecuador.
Habitat Preferences
The yellow-winged blackbird occurs primarily in marshes, swamps, wet meadows, flooded grasslands, rice fields, and along the edges of ponds and streams. It prefers open, shallowly flooded habitat with dense stands of aquatic vegetation. This species has also adapted well to some human-altered habitats like agricultural areas and parklands. Loss of wetlands is a major threat across its range.
Population Declines
Although yellow-winged blackbirds remain common and widespread overall, some local populations have declined, primarily due to wetland drainage and degradation. For example, populations are suspected to have declined in southern Brazil where over 90% of the Pampas wetlands have been converted to agriculture. They have also declined in parts of Colombia where 80% of wetlands have been lost since the 1940s. However, many populations remain stable and the species as a whole is not considered globally threatened.
Rarity in Protected Areas
Yellow-winged blackbirds occur in a number of protected areas across South America. Some key reserves where they have been recorded include:
- Pantanal National Park (Brazil)
- Llanos de Moxos (Bolivia)
- Kaa Iya National Park (Bolivia)
- Laguna de Llancanelo Reserve (Argentina)
- CiƩnaga Grande de Santa Marta (Colombia)
Within these protected wetlands, yellow-winged blackbirds remain common breeders and their populations are considered stable. They have not been reported as rare or threatened in these key reserves. Protected areas are important strongholds for yellow-winged blackbirds across their range.
Role of Seasonal Movements
Yellow-winged blackbirds undergo seasonal movements across parts of their range in response to water availability. Populations in Colombia and Venezuela migrate locally between breeding grounds and drier wintering areas. In Brazil, Paraguay, and Argentina, they are partially migratory with some populations remaining resident year-round while others move based on seasonal conditions. This adaptability allows populations to shift their range as needed, maintaining more consistent overall numbers despite local declines. Their movements make population sizes difficult to estimate precisely.
Comparison to Related Species
The yellow-winged blackbird belongs to a group of marsh-dwelling blackbirds in the genus Agelaius, which includes these related species:
- Red-winged blackbird (Agelaius phoeniceus) – very common and abundant species in North America
- Tricolored blackbird (Agelaius tricolor) – declining endangered species in California
- Crimson-collared grosbeak (Agelaius phaeniceus) – regionally vulnerable species in Peru and Chile
Unlike its declining and threatened relatives, the yellow-winged blackbird remains common and widespread. Ongoing conservation efforts for wetlands will help ensure the yellow-winged blackbird does not follow the same path as these rare and declining species.
Conclusions
In summary, the yellow-winged blackbird has a broad distribution across South America and occupies a wide variety of wetland habitats. While some local declines have occurred, overall populations appear stable, numbering in the millions of individuals. The species remains common across most of its continental range and is able to adapt to habitat changes. While not globally threatened, conservation of wetlands is needed to prevent future declines in this species. The yellow-winged blackbird’s flexibility and ability to move seasonally have likely contributed to maintaining stable overall numbers. With appropriate wetland protections in place, this species is likely to remain common, and cannot be considered rare across most parts of its range at this time.