This poor, shy lad will fly away when it comes in contact with either Mario or a sprite.
This is a C3 update. Now the birb animates correctly and gradually updates its speed instead of being a fixed static value.
You had GFX routine call after 9D check which made it disappear when getting hurt/power-up and etc. I've fixed that for you. Also I noticed that turning frame doesn't show up for some reason. Not a rejection issue though.
It's a cute little sprite for aesthetics purpose. And that's pretty much it.