Not as much hotwire as many other zoos. It drives me crazy when gorillas have a large exhibit with a handful of trees, and then those trees are all electrically charged. Why not give them a soccer field instead?
Hotwire is used to protect trees because without such protection the trees are very likely to be girdled or otherwise mechanically damaged by gorillas or other primates. A group of active young apes can decimate a mature forest in a very short time.
Note that the "vines" on the tree trunk in this photo are hotwires that artfully protect the tree. Congo has plenty of hotwires---they are just very well camouflaged. But there are smaller "sacrificial" trees not hotwired, along with much other unprotected vegetation that the animals can interact with (i.e. trash). A gorilla exhibit under a canopy of electrically-protected trees is a big improvement over a soccer field--which is what most would become without protecting the trees.
