Turn Resistance. The Zombie Goose has advantage on saving throws against any effect that turns undead.

Undead Fortitude. If damage reduces the Zombie Goose 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 Goose drops to 1 hit point instead.

Death Burst. When the Zombie Goose (or its egg) dies, it explodes in a burst of necrotic energy. Each creature within 10 feet of it must make a DC 15 Constitution saving throw, taking 14 (4d6) necrotic damage on a failed save, or half as much damage on a successful one. Nonmagical vegetation in that area withers.

Multi-attack. The Zombie Goose makes two Necrotic Beak attacks.

Necrotic Beak.  Melee Weapon Attack: +8 to hit, one target. Hit: 8 (1d8 + 4) piercing damage plus 7 (2d6) necrotic damage.