The Yian Kut-Ku is a fire-breathing bird wyvern. Kut-Ku is presumeably named after a cuckoo for its bird-like characteristic and appearance. It is rather small compared to other wyverns. They inhabit the Forest and Hills, Jungle, and Swamps. They resemble giant chickens, in manner and form. Yian Kut-Ku are the weakest of the boss wyverns, and many hunters defeat the Kut-Ku as their first wyvern. While experienced hunters have no challenge in defeating it, first-timers will have difficulty due to the Kut-Ku's speed.
They are belligerent towards hunters, and use their fire attacks and pecks to defend their territory. When they become endangered, they run away immediately. The most sensitive part of their body is their ears, which can be affected by various items which emit loud noises. They are weak against weapons with Ice element.
Their abilities are weaker compared to other monsters, and many times leave themselves open to attack. They often become enraged and fly away. They are comparatively stronger than other small sized monsters. After a while, they will start to limp and try to fly away. This can be stopped with a Sonic bomb.
As one can assume from their highly developed ears, Yian Kut-Kus have great hearing. Their ears are effective for hearing prey and enemies outside their range of sight, but because of their over-sensitivity, they are also vulnerable to explosive sounds. There are three ways to expose them to explosive sounds:Sonic bombs, barrel bombs, and Crag/Cluster Shots. Dizzied upon hearing a loud sound, Yian Kut-Ku's are stunned and become open to attack, but will become enraged once the dizziness subsides. Enough attacks to the head will break the ears. Also, an injured Yian Kut-Ku no longer is susceptible to explosive sounds as its ears are broken.
Yian Kut Ku is weakest to Water, Thunder, and Ice. Depending on the weapon class, you should attack it in a specific way for best results. For Dual Blades, always use Demonic Dance on its body with a Water weapon. For Longsword, slash away at its wings with a Thunder weapon. For Hammer and Hunting Horn, hit its head with an Ice weapon.You can also use Great Sword with Ice attribute and attack its head. The most effective attack on the Yian Kut-ku's head while using Great Sword is the triangle level 3 charge attack at the head while it's taunting you.
Yian Kut-Ku's ears fold back when it is near death; this would normally mean that it will try to run away to recover its health.
Sometimes, if you attack it before it sees you and is landing it will circle the area and swoop down on you.