What is the best way to exclude alien animals (e.g. Deer, Feral pig, Monkeys, Rats) in a study to find their impact on small epiphytes ?

Comparing between a fenced and non-fenced region seems to be a good way to do this for deer. But other species, e.g. monkey or pig, can easily bypass the fences. Any suggestions ? For smaller...

27 February 2016 9,125 3 View