Resisting animal and insect attacks of geomembranes is an interesting problem.  Geomembrane installers and manufacturers have had numerous geomembranes damaged by bears, deer, coyotes, birds, beavers and ground squirrels.  In most cases, the damage is incidental to something else the animal is seeking.  Deer damage the liner with their hooves trying to climb out.  Bears dig through the liner to try and find something on the other side (organic matter left under a liner in a retrofit).  Coyotes burrow under the liner on the slope to create a den that doesn’t freeze.