Flyby. The owl doesn't provoke opportunity attacks when it flies out of an enemy's reach.

Keen Hearing and Sight. The owl has advantage on Wisdom (Perception) checks that rely on hearing or sight.

Undead fortitude. If damage reduces the zombie giant owl to 0 Hit Points, it must make a Constitution saving throw with a DC of 5 + the damage taken, unless the damage is radiant or from a critical hit. On a success, the zombie giant owl drops to 1 hit point instead.

Talons. Melee Weapon Attack: +4 to hit, reach 5 ft., one target. Hit: 8 (2d6 + 2) slashing damage.