2021 Southern California Survey: Results

From April 2 to April 4, 2021, 14 participants, coordinated by Drs. Anita Hayworth and Rose Cook, surveyed 87 known tricolored blackbird colony locations in 5 counties in the 2021 Tricolored Blackbird Southern California Survey.  The 5 counties surveyed were Orange, Riverside, San Bernardino, San Diego, and Ventura.

Of the 87 locations surveyed, 9 were occupied.  The minimum estimate of the number of birds observed throughout the region was 2012 birds, the maximum estimate was 2835 birds, and the best estimate was 2459 birds, half of which were observed at the San Jacinto Wildlife Area in Riverside County.

Los Angeles County was not surveyed, but it is known that there was no water in the basin at Holiday Lake, the only location in the county in the past decade plus where more than a few hundred birds have been seen, and thus, that conditions at Holiday Lake were unsuitable for nesting.

There are many take-aways from these results, the most obvious of which are the near-extirpation of the species from the entire region and the critical importance of less than a handful of sites for the persistence of tricolored blackbirds in the portion of their range where they were arguably the most abundant a little over a century ago.