Harriet Tubman was a heroic abolitionist in the cause to end chattel slavery. She was also an excellent astronomer and naturalist — and an expert birder. She mastered the hoot of the Barred Owl, using it as a signal throughout the Underground Railroad to let freedom seekers know she had arrived.More info and transcript at BirdNote.org. Want more BirdNote? Subscribe to our weekly newsletter. Sign up for BirdNote+ to get ad-free listening and other perks. BirdNote is a nonprofit. Your tax-deductible gift makes these shows possible.