To move around quietly in a place trying not to be seen or heard, such as an animal does when hunting. (Cambridge Dictionary)
If an animal or a person prowls around, they move around quietly, for example when they are hunting. (Collins Dictionary)
To move about or wander stealthily in or as if in search of prey. (Merriam – Webster)
To roam over in a predatory manner. (Merriam – Webster)
(of a person or animal) move about restlessly and stealthily, especially in search of prey. (Oxford Dictionaries)
On the prowl. Slang looking for a sex partner.