From WoWWiki

Moon Horror Den is a small cave habited by Raging Owlbeast Note: they are most likely not there because of players doing the wild guardians quest. It is situated quite close to Everlook, just a short walk to the northeast from the city gates. Despite its apparent closeness to the Winterfall Village however, the mountain itself blocks a direct path and a long ride around is needed to head further south from the cave.

Subzones of Winterspring
Darkwhisper Gorge • Dun Mandarr • Everlook • Frostfire Hot Springs • Frostsaber Rock • Frostwhisper Gorge • The Hidden Grove • Ice Thistle Hills • Lake Kel'Theril • Mazthoril • Moon Horror Den • Owl Wing Thicket • The Ruins of Kel'Theril • Starfall Village • Timbermaw Hold • Timbermaw Post • Winterfall Village