I suspect that to some extent the policy is in place as a "don't ask, don't tell" measure - if someone directly enquires about it, the zoo has to enforce it because it IS in their official conditions of entry and the individual concerned has acknowledged this, but otherwise it is not enforced and is present to give them the legal ability to crack down on specific photographs if they so desire.
Interestingly, I think that the prairie dog pup in your photo is not well, in spite of the zoo's approval. Perhaps I am wrong, but I have linked a photo of a healthy pup in my comment on your photo.
I just saw that comment and after seeing the photo of a healthy one I decided to delete that specific photo that I uploaded. I clearly know nothing about prairie dogs The reason being, that I'm not uploading the photos to show any flaws or to portrait the zoo in a bad way. Just generally want to share some really nice exhibits and animals
I think I would have done the same myself. But I also think that it shows that your photos were not exactly scrutinised by the zoo.
