OBSOLETE - MCAS Tricolored Blackbird Monitoring Program





The Tricolored Blackbird is North America’s Most Colonial Landbird 
Breeding colonies are often teaming with more than 50,000 birds, sometimes all crammed into a 10-acre field or wetland to raise their young. While similar to the more widespread Red-winged Blackbird, it can be distinguished by its crimson red shoulder patch with a bright white bar, in contrast to the orange-red patch and yellow bar of the Red-winged Blackbird.

Struggling to Make a Comeback
In the 19th Century Tricolored Blackbird flocks were described as so numerous “as to darken the sky.” Since then, the population has declined from in the millions to less than 500,000 today. Over just the last 70 years, the Tricolored Blackbird population has decreased by more than 80%. The reasons for this decline are many, but the loss of marsh and nearby foraging habitats along the coast and in the Central Valley is the main issue. In more recent years, the species has become dependent on agricultural lands, with most of the largest colonies nesting in grain fields. This is a real problem, because usually the young have not yet left the nest around the time farmers harvest their crop, and harvesting destroys Tricolored Blackbird nests and young. In some cases as many as 20,000 nests have been lost in a single field.

Why Tricolored Blackbirds are Important in California
Tricolored Blackbirds are nearly endemic to California, with over 95% of the world’s population occurring only here, including scattered small colonies in San Luis Obispo County. Thus, in California we have a unique responsibility to protect this species so that future generations can witness the spectacle of the largest breeding colonies among North American landbirds.

How to Help
The first step in making a difference for Tricolored Blackbirds is to identify and keep track of the location, status, and changes of Tricolored Blackbirds in our county. This information is critical for
understanding how things are changing and making sure that colonies that can be enhanced or protected are identified.

Known Colonies in SLO County (PDF)

Download an observation form

Annual visits to each of these colony sites and new ones that are found is a great way to work with Audubon California and its partners to protect this species.

If you have any questions or ideas please feel free to contact Andrea Jones