This sounds like a riddle! Here is how to think about it:
* Sheep bleat: This is their way of communicating.
* Foxes are predators: They like to eat sheep.
So, what does a fox do when it hears a sheep bleat? It probably...
* Listens closely: trying to pinpoint the sheep's location.
* Sneaks closer: to get a better chance of catching the sheep.
Let me know if you would like to try another riddle!