As reported here, California's Tricolored Blackbirds (wiki) are in trouble. Populations have fallen 64% since 2008 and 44% since 2011. A survey released Wednesday indicates that there are only 145,000 birds left, out of a population that once was in the millions. The survey was led by UC Davis in conjunction with the U.S. Fish and Wildlife Service, the California Department of Fish and Wildlife and Audubon California.
Like their close cousins, the Red-wing Blackbirds, their preferred habitat is tules, cattails and similarly tall grasses and such. They live in enormous colonies and seldom travel more than a few miles for food. As California's historical wetlands dried up and disappeared, the birds have had trouble finding sufficient habitat.
Most of them have flocked to the dairy farms of the Central Valley where they roost and nest in fields of grain grown to feed the dairy cattle. Unfortunately, the grain is preferably harvested before the birds and their young are ready to relocate. The mowing operations kill thousands of baby blackbirds and eggs.
"Literally, in the span of 10 minutes, 10 percent of the global population of this bird can be wiped out," said Daniela Ogden, a spokeswoman for Audubon California.
As a result, scientists have been working with farmers to create safe havens on their land. A program through the U.S. Department of Agriculture pays dairy owners to harvest their crop only after the birds' young are born and able to fly away. Some dairies have voluntarily delayed their harvests.
There are also ongoing attempts to create replacement wetlands, but California is in the middle of a severe drought.