Keen Sight and Smell. The zombie owlbear has advantage on Wisdom (Perception) checks that rely on sight or smell.

Death Burst. When the zombie owlbear dies, it explodes in a burst of guts and decay. Each creature within 10 feet of it must make a DC 12 Constitution saving throw, taking 2d6 poison damage and receiving the poisoned condition for two rounds on a failed save or half as much damage on successful one.

Undead Fortitude. If damage reduces the zombie owlbear 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 drops to 1 hit point instead.

Multiattack. The zombie owlbear makes two beak attacks.

Beak. Melee Weapon Attack: +7 to hit, reach 5 ft., one creature. Hit: 8 (1d6 + 5) piercing damage.