Big Lashes  I took this with my 24-55 lens.  The trick to shooting subjects behind glass is to put the lens right ON the glass.  The camera will often disregard any debris or scratches on it because it is so close.  This guy was "attacking" my tripod, that I had leaned up against the glass.  I got this photo while he was worried about the intruder.

             

                                                 Snuggle.  The warthog on the right is a female in estrus.  The one on the left is her suitor.  I shot this with my 55-250 lens.  Again, right on the glass. If you sit and observe and don't rush, you can get all kinds of cool shots.  I recommend going by yourself with people who understand that they won't be going to the zoo with you per se.

                                                 Tandem.  I think we all have a fascination with primates, especially the apes.  And just to clarify:  Apes don't have tails Monkeys HAVE tails....that is an easy way to tell the difference.  And WE ARE APES!! These, our very close relatives, are dying in the wild because of human doings.  I shot this with with my 55-250 lens.  I got to the bachelor habitat about 10 minutes before feeding time.  These two dudes were watching some keepers strolling around the perimeter of their enclosure.