Yellow Bird is another unique monster, located on the road to Bale, on the world map. It tends to run away, but offers 300 gold upon defeating it, as well as an Elude Cloak a small percentage of the time. Methods to defeat it are listed below.
The Yellow Bird can run away and is quite fast. If it stays in battle, attack with your first turn character. If you land a hit (for 1 damage) have your next character throw the Signet Stone. Continue attacking until defeated. It has high evasion, so Wargod's Amulets and Armets will help you land your Physical Attacks.
The second is using a Sachet. This is recommended as a secondary since Sachets are extremely rare, and a pain to obtain. A Sachet will do 10 HP of damage, immediately securing victory, as well as your 300 gold.
As for all special monsters, it is recommended you find the Speed Up, Speed down, and Signet Stone repeatable items to help increase your odds of killing said monsters.