Tree structures are simply post structures that are modified for mounting in trees
(Figure 4). Their advantages are that they can be
used where water levels rise dramatically, can be inconspicuous if desired, and
the trees provide stable supports. The disadvantages are that they are not predator
proof, they may be difficult to maintain, and hawks and owls may compete for the
nest sites with the geese. When placed on trees over water, the structures should
be mounted 3 to 4 feet above the maximum anticipated high water level. When placed
over land, they should be mounted 6 to 20 feet above the ground or 3 to 4 feet
above flood stage.