The best place to aquire prowl ( at it's highest level) is in Winterspring.  The Frostsaber Stalkers at Frostsaber Rock have this ability  (beast lvl 58).

Alternatively, there are panthers in STV (beast lvl 30ish)who have the prowl ability (lowest level)... if you look around the middle regions of STV, you will find them.

Happy hunting