Bluetails are red and blue colored flying creatures.
Upon a Prospector getting close to a group of Bluetails they will make a squawking noise, signalling they have been startled. If the Prospector makes more noise or moves closer to the Bluetails, they will fly away, making a flapping noise and screaming. When The Cycle (storm) starts all Bluetails will fly away even if no Prospector are near them. Bluetails continue to spawn during the storm, making them fly away instantly upon spawning. This behaviour is likely a bug. Bluetails always spawn in the same locations and respawn approximately every 5min even if a Prospector is close. All Bluetail spawns can be found here: Interactive Map