They don't. I had a racoon coming a couple of times during the day. When we drove it off, it just climbed up a big tree and then stared at us. The standoff lasted several minutes, finally it decided to back off by climbing down the tree then out of the fence. Luckily, it came for chicken feed...
I'm so sorry for your loss. I too lost one of leghorns to a pair of bob cats in my backyard. (Luckily,) I didn't see when it happened. I only saw one of the bob cats stalking my flock who ran close to the house already. I jumped into the icy water and it backed off, and only then I saw another...