It's gotta be my favorite webcomic.

i have his book and it's great, my niece and nephew always look at it when they visit (8 & 11)

his old second comic was called Trash Bird and it's one of my absolute favorites

Oh, hell yeah!

Squirrels are theives though. Always mooching off the bird seed. 

My favorite fictional animal

It is a strong contender, and I have quite a few PDL favourites.

And that's why they can't be friends. Squirrels steal bird food which makes Birds angry so they peck the squirrel to death.