An article by Dick Erickson, Horacio de la Cueva, and Enrique Zamora-Hernandez in the journal Western Birds documents the steep decline in abundance and contraction of the range of the tricolored blackbird in the southernmost portion of its range in northern Baja California, Mexico.  The authors found that fewer birds nested in fewer colonies in 2019 than at the turn of the 21st Century, with but a single colony consisting of about 150 breeding birds documented in 2019.  These effects were believed due to persistent drought, rising temperatures, and agricultural intensification.

You may access their article here.