LOL..... well maybe 'secret' is stretching it a bit... but they are 'off the beaten path' and very subtle. They are a great touch, and just add to the magic of MiraCosta & DisneySea.
Kind of like those nooks and crannys all throughout Disneyland Paris (especially in Adventureland & Frontierland), the 'secret' bathroom to the right of Plaza Pavillion in Disneyland Anahiem, the numerous paths throughout Animal Kingdom, etc
By the way, none of those pics even show the specific garden paths I'm thinking of (although they are in the area!)
Correct me if I am wrong but it was my understanding such "secret" paths were closed or blocked off at DAK, and guests can't stroll on them anymore.
If you are talking about those two paths that let you see the various animals you don't see on the tours in African and Asia, they are open and advertised heavily. I don't know what "Secret" paths you are referring to.