For those of you who would prefer a picture guide, I found this great guide on gamekult.comThe guide is in french, but it is all pictures, no descriptions so you do not need to be able to speak french to be able to use it. The names of the areas and levels are in french, but it is still very easy to understand as they are in order.
Or if you would prefer a written guide, there is a brilliant one on Gamefaqs thanks to James Novotny. It was originall written for the PS3 version, but everything is in the exact same place.Some extra information thanks to
GRAND NOBLE:
A couple things you should know:
1. Each level has 1-3 cages.
2. The levels all END with a cage, so this is not considered a "HIDDEN" cage.
3. You don't have to break the cage(s) for the achv to pop, you just have to enter the 'secret room' where the cage is.
WORLD 1: Jibberish Jungle
1-1 - Only 1 cage, doesn't count.
1-2 - 3 cages (2 hidden).
1-3 - 3 cages (2 hidden).
1-4 - 3 cages (2 hidden).
1-5 - 3 cages (2 hidden).
1-6 - Only 1 cage, doesn't count.
1-7 - Only 1 cage, doesn't count.
WORLD 2: Desert Of Dijiridoos
2-1 - 3 cages (2 hidden). *This is the earliest chance to get the achv*
2-2 - 3 cages (2 hidden).
2-3 - 3 cages (2 hidden).
2-4 - 3 cages (2 hidden).
2-5 - Only 1 cage, doesn't count.
2-6 - Only 1 cage, doesn't count.
By the end of World 2, you should have run across 16 "HIDDEN" cages!
More than enough for the achv.