These are hidden in the trees among loads of Baby Gargoyles south of Behr Town. The Mutated ones drop down from the trees in a few locations and stick out since they don't fly like the babies and are a bit larger. They kind of look like giant angry hairless "flying squirrels" imo. My suggestion is run around spamming some AoE and mark the locations on your map/minimap of about 3 of them and run between those 3 points until you get the knowledge.
Credit: http://forum.blackdesertonline.com/index.php?/topic/39608-how-to-find-mutated-gargoyle/

3 punkte gibt es dort im Kreis versteckt leider.

Can't see it up in the tree, it is literally invisible, however all of the trees look the same and there are always nests at the bottom, look for those and watch your cross hair to get red out of nowhere

Eles ficam escondido em meio a árvores com galhos
They're hidden in the threes
https://imgur.com/gallery/KqqJKUE

Ride horse little bit easier to find Mutant Gargoyle, This guy will hit your horse
Look on the ground
https://youtu.be/8sZTOrN6RZg?si=hF1oza19oFG3OAf4