Here's why:
* Hawks are predators: Hawks are much larger and more powerful than foxes, making them dangerous prey.
* Foxes are opportunistic feeders: Foxes primarily eat small mammals, birds, insects, and fruit. They might scavenge a dead hawk, but they're not known to actively hunt them.
* Hawks are agile: Hawks are excellent flyers and can easily evade foxes on the ground.
While there might be rare instances where a fox could kill a young or injured hawk, it's highly unlikely for a fox to actively hunt and eat a healthy adult hawk.