Audublog

Everything you need to know about the decline of the Tricolored Blackbird in one chart

April 23rd, 2014 · by Garrison Frost

TCBL_lee_karney_usfws500p

As anyone reading this blog knows, Audubon California is committed to making a future for the Tricolored Blackbird, an increasingly rare species that is struggling for survival due to several factors. In recent years, Audubon  California and our many partners have taken a two-pronged approach. When birds have set up massive breeding colonies on dairy farms, we work with landowners to delay harvesting so the chicks can fledge. We’re also trying to keep colonies off dairy farms by creating wetland habitat for the birds in other areas. While these efforts have saved many thousands of birds, staving off a potentially irreversible population crash, the Tricolored Blackbird’s decline continues.

A 2008 survey of Tricolored Blackbirds identified approximately 395,000 birds in California. In 2011, a similar survey counted about 259,000. That’s scary, but it actually gets worse. In that 2011 survey, it became clear that the greatest concentration of Tricolored Blackbirds occurred in three Central Valley counties: Merced, Tulare and Kern. Those three counties alone accounted for more than 230,000 Tricolored Blackbirds. In 2012, we went back to those three counties and did an informal survey of the colonies. And we counted just over 90,000 Tricolored Blackbirds.

Here’s the key graphic:

trbl_colony_table

The above chart of colony sizes puts the situation in even more dire terms. The black bar indicates the largest colony size, while the red and white show the top three and top five average, respectively. Since 2006 we have seen an 85 percent drop in the largest colony size and overall the largest colonies have all been getting smaller.

Tricolored Blackbirds live, on average, seven to eight years. All of the young last produced in 2006 are now getting old and dying, and without the reproductive success in last seven years, we are literally at the edge of a demographic cliff for the species.

This downward trend of the Tricolored Blackbird indicates the critical need to continue our conservation efforts around this species — and moreover, the need to work even harder. You can help save this species by making a contribution today.

Categories: Audubon California · Bird Habitat · Tricolored Blackbird

4 Comments so far ↓

  • Deena Nissley

    Thank you, Bob Toleno!

  • Liana

    Mr. Frost: I’ve seen no further reports about the dairy farmer’s field for which Audubon was trying to raise crowd funds to pay off. What came of that issue? Did the farmer harvest the field yet or not? Thanks for any updates.

  • Bob Toleno

    In Colorado, those would be Red-winged Blackbirds, Deena. Tricolored Blackbirds only live in California, Baja California, and a small section of Oregon.

  • Deena Nissley

    We have hundreds of them on our ranch here in Durango, CO