Much like Monster Hunter World, Iceborne offers players the opportunity to capture small, rare pets for achievements and to decorate their room. The pets and achievements associated with them, depending on a variety of factors. They might be time dependant, appearing only at certain times of day or night. They could be location-dependent or a mix of the two.
The Sweet Melody Achievement is unlocked by capturing the Blue Diva. The Blue Diva is a blue parrot-like creature with long tail feathers. According to RPGSite, the Blue Diva can be found in the Wildspire Wastes, in Area 5. However, others have found it in the Ancient Forest.
The weather must be clear, and it must be during the day for the Blue Diva to appear in the Wildspire Wastes. You’ll be able to find it on a rocky peak in Area 5. There’s a small nest just under the peak of this climb. It may sit calmly singing on the small roost area, but if startled, it will fly in circles so you’ll need some patience.
It might be hard to spot it, so make sure you’re wearing headphones. It’s called Sweet Melody because the Blue Diva loves to sing and wants you to hear it. If it’s spawned, you’ll probably hear it before you see it.
After catching it, return to your room to place it and interact with it.