“If monitoring ceases and the boxes aren’t taken down, they’ll all be taken over by house sparrows,” said Sivertson. He was instrumental in making sure decades of data were collected and tabulated regarding Lake County bluebirds. He recalled in 2008, volunteers helped fledge more than 1,000 bluebirds. As insect populations decline and when trails are no longer monitored, that number can plummet.
Volunteers monitor man-made boxes to help native songbirds – Chicago Tribune