That's odd, as I have found on recent visits that the gorillas are most active in the early to mid afternoon, but are entirely indoors (or sometimes not even visible, often retreating to the offshow portion of their indoor area on the other side of their overhead passage) by the late afternoon. On my visit last Friday, for example, we had some excellent gorilla activity shortly after lunch time exploring the outdoor area, before they went indoors, and then after some great activity there, they went to the offshow portion. A return to their exhibit later on in the day revealed that they were still offshow. Perhaps, as a result of their intelligence, gorillas have a more varied routine, or perhaps the birth of the two babies has made them more unpredictable?