What happens to the puzzle pieces when you release all the sanctuary animals

Now I'm nearing the collection of all the required PP's to complete my my sanctuary ( max of 6 weeks and I'll be done) it got me wondering about what happens to the pieces once this is achieved?

I am hoping that the puzzle pieces still appear as I guess that Supercell will be adding more animals and expanding the sanctuary further in the future and therefore I would still like to collect my 4 or so a week to contribute towards this.

One for Frisco I expect unless there are some forum members that have all their animals and can answer for me?

My understanding is they are like permits. Once you get them all you stop getting them. I need 4 more so I'm not there yet but I remember reading that when it first started. Im trying to find it to reference to you but haven't been able to yet.

You won't get any until SC release a new animal for the book.

Thanks smallchange

You won't know until you get all the animals.