|He almost looks like a distant relative of Jack Skellington from the Nightmare Before Christmas.|
You are introduced to Birdy fairly early in the game, in a tutorial sequence that teaches Conker how to use context-sensitive platforms (which are just platforms you stand on in order to activate a special power-up specific to that area of the map). After you get over the shock of having a creepy-looking scarecrow come to life and talk to you, you immediately notice that this guy is totally wasted. What follows is a hilarious conversation between Conker and Birdy where Birdy tries to explain the concept of context-sensitive areas, while clearly not knowing the meaning of context-sensitivity.
But in the end, Conker finally uses a nearby context-sensitive (trust me, after watching this sequence of the game, you will never get tired of saying "context-sensitive") platform to give a beer to his new straw-filled buddy.
Sadly you only run into Birdy at one other point in the game, during another funny sequence where he rambles on about reading manuals and wanting Mepsi Pax (a play on Pepsi Max, a favorite drink of a member of the Conker development team who was nicknamed Beardy). Whether you love him or are annoyed with him, you have to agree that Birdy is one weird and unique character!