This video from the USA says about itself:
On May 24, 2017, Jason Estep noticed something unusual. A male Eastern Bluebird was inspecting an old [American] robin’s nest above a light fixture in an open-air facility in Franklin County, Ohio. He had seen a bluebird pair in the area on previous occasions, but did not think much of it until the male appeared to start working on this old robin’s nest. Jason then monitored the nest for eight consecutive days and found, each time, a female bluebird sitting low in the nest. She appeared to be incubating! Here.