minecraft-assets/data/minecraft/chicken_variant/_all.json

{"cold":{"asset_id":"minecraft:entity/chicken/cold_chicken","model":"cold","spawn_conditions":[{"condition":{"type":"minecraft:biome","biomes":"#minecraft:spawns_cold_variant_farm_animals"},"priority":1}]},"temperate":{"asset_id":"minecraft:entity/chicken/temperate_chicken","spawn_conditions":[{"priority":0}]},"warm":{"asset_id":"minecraft:entity/chicken/warm_chicken","spawn_conditions":[{"condition":{"type":"minecraft:biome","biomes":"#minecraft:spawns_warm_variant_farm_animals"},"priority":1}]}}