Are elemental planes, and other planes in general, full of normal looking animals?

[Crimeo]

When you cast summon monster, it says you summon "celestial monkeys" and so forth. Am I correct in interpreting therefore that some plane(s) out there are just chock full of mimics of every random kind of animal, but as outsiders not animals? If so, is there any clue as to WHICH planes, exactly? Like is the plane of air full of outsider swans and thrushes and stuff in addition to air elementals? Or do these things live in places like Nirvana? Or is there just no clear RAW info on this?

[CampinCarl9127]

The planes are infinite and hold all possibilities. I would presume to say the celestials come from certain good aligned planes, possibly the well known ones, possibly others.

The planes are my area of expertise, and as far as I know there is no clear RAW answer for this.