Ways to change the size of an Animal Companion?

[StygianRose]

Title says it all.

I am playing a Hunter and I intend to use the 'Bird' animal companion for some specific synergy with teamwork feats.

(Namely the fact that while it rides my shoulder every space is considered adjacent to use for Escape Route and thus we never provoke for moving even if doing moonwalk cartweels)

However it does not ever grow larger than small so I was hoping that someone might know of a way to temporarily make it large so that it may be ridden or otherwise a way to make myself Tiny so that I can ride it.

Or a way to turn myself into a bird so I can fly with it, all of these are acceptable options really.

[Spore]

The Dire Collar (http://www.archivesofnethys.com/MagicWondrousDisplay.aspx?FinalName=Dire%20Collar) increases the size of your animal by one category for one minute.

[skypse]

What about this here (http://www.d20pfsrd.com/classes/prestige-classes/other-paizo/i-m/mammoth-rider)? It might not fit mechanically, but you can certainly ride it and it would be tons of fun :D

[Unbodied]

You could pay a wizard/psion to cast/manifest a permanent shrinking spell/power on the birdy.

[SlyWolf]

The Dire Collar (http://www.archivesofnethys.com/MagicWondrousDisplay.aspx?FinalName=Dire%20Collar) increases the size of your animal by one category for one minute.

My DM gave us one of these but it's always Enlarged as long as it stays on the animal. There's no activation required.