The Wood Duck Society Board of Directors, at our January, 2004 meeting  adopted a “Best Practices” method of nest box mounting. The method involves bolting a wooden box to a pole, with the hole just six feet from the ground. A sheet metal cone predator guard is placed just below it, with its lip at least three feet from the ground. The box should have a side-opening door, allowing monitoring to be done on a walk-up basis. No ladders are ever necessary.
   
Cone Rationale: This technique is not new. In 1958, a drawing illustrating a nearly identical box and cone method appeared in a U.S. Fish & Wildlife leaflet, written by Clark Webster. No predator guard is 100% effective against mammalian predators, but this one comes very close (In northern Minnesota, however, bears remain unimpressed). My southern friends tell me that rat snakes, when five foot and longer, can shift enough of their weight over the top of a three foot cone to allow passage to the box. And avian predators, of course, are not deterred.
   
The cone guard has stood the test of time. Bellrose and Holm, in their book, Ecology and Management of the Wood Duck, published in 1994, stated: “When constructed to the proper dimensions and snugly fitted, cone shields provide the best available protection against pole-climbing predators.” On my own 100 box unit in Minnesota, on a wooded farm rife with raccoons, mink, and squirrels, I shifted in desperation to this technique over twenty years ago. The mammalian predation rate, when eggs, hen, and brood are in the box, promptly plummeted to zero and has stayed there. Nest competition from squirrels is no longer a problem here.
   
The perception seems to be that cone guards must be difficult to construct, and might be too expensive. Neither perception is true. Jr. High students at a summer waterfowl camp routinely learn to affix the cone in less than ten minutes. Cost for cone, brackets, and peace of mind =$10 (see sidebar for sources).
   
Usage: Wood duck hens use (some studies have found they prefer) low-mounted boxes. Higher is not better, only more dangerous and difficult. Expect nest success with this system, and expect successful hens to come back, along with some of their female offspring, if they survive the rigors of migration and wintering.
   
 Tools: Portable drill with bits, wrench, and Vise-Grip pliers. The Vise-Grips hold the overlapped edges of the sheet metal in a cone shape after it is wrapped over the supporting brackets. Holes are then drilled, and small carriage bolts used to fix edges together and to attach cone to brackets. Paint cone an earthtone color.
  
Poles: The strangest reason for resisting the pole-mounting method is the tenacious, almost visceral, and sometimes dangerous need to bolt boxes onto trees. This ladder climbing may persist for years, often including unending battles with mammalian predators, since trees are difficult to make predator-proof. Thirty years ago, I used to stay awake nights, dreaming up questionable schemes to retrofit my tree-mounted boxes in an attempt to make them less hospitable to predators.
   
Without ever gaining inside access, raccoons on top of a box can cause a hen to abandon her clutch. Even worse, when the harassed hen sticks her head out, she may lose it to the raccoon.
   
In contrast, poles allow easy attachment of effective predator guards. There is then no need to retrofit boxes with add-on features designed to discourage climbing predators. Key: Keep predator from reaching the box in the first place.
   
Eight-foot treated landscape timbers (flat on two sides) work well and cost $4. Using a post hole digger, carve a hole two feet deep. Place pole, tamping dirt firmly around its base. Bolt box to pole so the bottom of hole is six feet from ground. If discarded stop sign poles are available, pole placement is easier and cheaper, and can then be done in wet areas as well, joining two or more sections together as needed. Bolt support brackets right below the box, and affix cone guard, as described above.
   
Placement: Wood ducks have evolved to nest in tree cavities. Place pole-mounted boxes near trees and near brood habitat, where they will be found easily by cavity hunting hens. However, gray and fox squirrels can leap 8 ft. horizontally from tree trunks, and drop 11 ft. from overhanging limbs, so plan accordingly.
   
Heat: Pole-mounted boxes are seldom in complete shade. Temperature studies have shown that boxes made of metal, plastic, and even plywood, when exposed to direct sunlight on hot days, can become too hot for egg survival (107 degrees F.). The hen may abandon well before that point. Studies done here (Newsgram # 16, Dec. 1995), found that metal and plastic boxes reached 118 degrees F. on a 94 degree June day in Minnesota. White paint and vent holes help, but it’s better to choose boxes built with natural, 7/8” thick boards. Such boxes resist heat build-up on sunny, hot days.
   
Teaching Bonus: This “Best Practices” mounting method allows safe, hands-on teaching. Even small children can be brought nose-to-nose with the eggs by using a simple step stool. If you doubt the value of this, try it, and take a look at their faces. The wood duck box just might be the best ecological teaching tool ever devised.