His most recent book is Grizzlies of Pilgrim Creek: An Intimate Portrait of 399, the Most Famous Bear of Greater Yellowstone, with photographer Thomas D. Mangelsen. Follow him on Twitter. The sow took Matheny down, chomping on his head. Matheny thought it was the end—until his companion emptied a four-ounce can of bear spray into the face of the bruin, causing it to flee.