Bird Bones

“Test subjects displayed significant atrophy to skeletal structure, decreased intelligence, and a loss of appetite.

Heightened reflexes, attentiveness, and paranoia were also noted.

Subjects were increasingly distressed at any change to environment and perceived threats in any nearby sudden movement and/or loud noise.”— The Whitespring bunker terminal entries

Bird Bones is a mutation in Fallout 76.

Overview

Positive effects
+4 Agility +40 AP -45% fall speed -90% fall damage	+5 Agility +50 AP -65% fall speed -95% fall damage
Negative effects
-4 Strength +20% limb damage received

Interactions

Falling damage reduction stacks multicatively with Goat Legs and Acrobat's Legendary mod
Falling speed reduction stacks additively with lead champagne.
Although the description says that the mutation improves the ability to sneak, it does not actually do this (apart from increasing agility, which improves sneaking).