Here is the full list of all 30 Birdcakes achievements.
Lose for the first time
Kill a fly
Kill a fly with a hat
Kill a sugar licking fly
Kill a yellow fly
Kill an enormous fly
Kill a burping fly
Kill a bull fly
Kill a tiny fly
Kill the tiny fly army
Kill a ghost fly
Kill a skeleton fly
Kill a demon fly
Kill a sniper fly
Kill a missile launcher fly
Kill a robotic fly
Kill the big metallic fly
Kill a coin fly
Kill a piñata fly
Kill a candy fly
Kill a muscular fly
Kill a big jelly fly
Kill a medium jelly fly
Kill a tiny jelly fly
Kill a laser fly
Kill the heart
Kill the brain
Kill the giant chunky monster
Beat a wave with the pink cupcake.
Wake the red cupcake up