The Tricolored Blackbird - Agelaius tricolor - is a near endemic California passerine and the most colonial songbird in North America. The male is glossy-black with a red shoulder patch and bright white bar, while the female is dark blackish-brown.

Its range is limited to the Pacific coastal areas of North America, from Northern California to upper Baja California in Mexico. Found almost exclusively in California with more than 99% of the individuals in California.

This highly social and gregarious bird forms the largest colonies of any North American landbird, with a single breeding colony often consisting of tens of thousands of birds.

The common name is taken from the male bird's distinctive white stripes on bottom of their red shoulder patches, or "epaulets", which are visible when the bird is flying or displaying.

Males arrive on the breeding sites 1-3 days before the females in March. They nest twice and the second breeding attempt often occurs in a different, more northerly location. In most cases, one male breeds with two females in each breeding attempt. An open cup nest is built and three to four light blue eggs are laid. Females incubate for roughly 12 days, with young fledging between 10 to 14 days.

Tricolored blackbirds are mainly granivores, however, they consume a wide variety of plant and animal food and respond opportunistically to the most abundant, readily available food resource.

The results of the 2011California Statewide Survey show a dramatic drop in the number of tricolors statewide, from approximately 395,000 in 2008 to about 259,000 this year, a greater than 33% decrease, this despite an increase in the number of sites visited and an immense effort by 100 survey participants.