Building a Nest Box


First Things First:
Before you start hammering and sawing, there are two questions you should ask yourself:

1.  What kind of owl do I have a chance of attracting? The three owls that are the best candidates in North America are the Barred Owl, the Screech Owl and the Barn Owl. If you have never heard one of these in your area, you are not likely to attract it. You know what the barred owl sounds like from OwlCam, and can learn the screech and barn owl's calls at the www.owlpages.com site. Screech owls are the easiest to attract and most compatible with human activity in most parts of North America. I will not address the barn owl, as I have no experience with them. Your local Audubon society or birding clubs can be excellent sources of information. If you are lucky enough to have burrowing owls in your area, take a look at the nest mound plans at http://www.srcsd.com/nestsite.html

2. Can I give the owls the tranquility they need to nest successfully? Northern Barred Owls have the lowest tolerance for humans and will abandon their young if they get more than a couple of human disruptions per week. June the barred owl will be flushed out of the nest by any human activity within 100 feet of her nest box. Many barred owls are less sensitive and select natural cavities within thirty to fifty feet of human dwellings; but there is no way to tell in advance and you should locate you nest box as far away from human activity as possible to maximize chances of nesting success. The Screech Owl is much more tolerant and will often nest within ten to fifteen feet of a residence. Even they will not tolerate frequent disruptions. You are disrupting an owl if it is spending more than half of its time staring at you. An owl's nest box should never be put in a location where it will be subject to large numbers of curiosity seekers or possible vandalism.

Building the Box:
After you have decided what kind of owl you want to try to attract and assured yourself that you can protect it, you are ready to proceed with building your nest box. I will not cover basic carpentry concepts here as these can be found in many library books. The instructions that follow are for the 14-inch x 14-inch x 28-inch-deep barred owl's nest box, but also apply to the screech owl if scaled down to their modest 8-inch x 8-inch x 12-inch-deep requirements. If you lack the tools or woodworking skills, you might consider buying a nest box. Many local birding and garden shops will special order owl's nest boxes. There are also several on-line manufacturers including Coveside Conservation Products at www.coveside.com

Tools: I used a table saw, power drill and jigsaw. You might get by with a hand-held circular saw, hammer and nails. The jigsaw is used to cut out the eight-inch diameter door and I will leave it to you to decide if you could do without it.

Materials: About 30 feet of l"x10" lumber (I used pine) for the sides and bottom, plus one 20" x 20" piece of plywood for the roof. I used scraps of two-by-fours to make the owl rail brackets and tree branches to make the rails themselves. My nest box is held together by 1+1/2", 2" and 3" deck screws. You might prefer nails if you do not have a power drill. You will also need about 1/2 cubic ft. of woodchips from well-aged, or rotting, hardwoods to cover the floor. Other materials to dress up the appearance are strictly a matter of taste. I used cedar shingles because a box that big can be a bit of an eye sore. June and Ward have not said whether it influenced their decision to move in.

railing.jpg (16154 bytes)Construction: I'm not a woodworker and did not work with plans or drawings. There are many ways to do it and I will only describe the one that worked for me. It is an approach that allows you to see the box take shape and make adjustments as you proceed. While you start with 10" lumber, you will be trimming it to 7" or 7-3/4" as required to meet the dimensions specified:
(1) Build the floor from two 7-inch by 14-inch boards side by side. Screw or nail them to a frame made of scraps to hold them together. The frame should be on the bottom. Be certain that the sharp tips of nails or screws do not protrude through the top surface as the owls and owlets would cut their feet as they try to dig through the floor.
(2) Make the sides by first laying two boards (trimmed to seven-inch width) side by side. Line them up on the bottom and mark the sloping roofline on the top. The front of the roofline should measure 30 inches from the bottom and the back about 34 inches. Cut along the line you marked and then screw the boards to the outside of the floor platform so that you can see the box take shape. Repeat this for the other side and screw it to the floor. You now have a two-sided owl house without a roof.
(3) The front and back will be sized and cut to fit what you have assembled so far. The lumber for the front and back will be trimmed to 7 and 3/4 inches rather than 7 inches so that it covers the side pieces. Put the boards in place and mark them to fit. Note that the top cuts must be made at a thirty degree angle to keep the roofline straight.
(4) Go ahead and screw the back on, but hold off on the front until you have cut the door out. To do this, draw an eight-inch circle four inches below the top and cut it out with a jigsaw. This would also be the time to screw on the rail brackets (six four-inch sections of two-by-four) if you plan to use owl rails. Mount them about four inches below the bottom of the door opening and close to the outside corners--two on front and two on each side. I cut branches for the rails and screwed them to the brackets after mounting the box on the tree to get the best fit. You should also construct some sort of "owlet ladder" (anything that an owlet can hook its claws on to climb) and fasten it to the inside of the front panel just under the door. Owl rails and an owlet ladder are options for you to decide on for the barred owl. I would not use rails for the screech owl as they are too small to defend themselves against climbing predators that might use the rails. Both the adults and the owlets used the rails and ladder on my box and I plan to retain them. Next, screw the front on the nest box.
(5) Finally, screw the 20" by 20" piece of plywood to the top so that it is flush with the back, but overlaps on the sides and front. I used a strip or aluminum flashing on the back to eliminate leaks, but this was more for the electronics that I put inside than for the owls. I also added trim to cover the outside edges of the plywood; but again, strictly for appearance. You are now done with the basics. Any roofing material, shingles or other decorations are a matter of taste. Be creative.
(6) Add about two inches of  wood chips to to floor. This provides insulation and cushioning for the eggs, and gives the female something to chew on.

Caution: If you are not extremely adept at working on a ladder, you should hire a professional tree cutter to mount your box. Attaching a fifty-pound box to a tree while dangling eighteen feet up is extremely risky. I first secured my box with ropes and pulleys, and then attached it by reaching through the door with a power drill and screwing it to the tree.

Placement: The box should be put up as early as possible, but not later than one month before nesting season. It should be mounted at least fifteen feet up in a large tree. I strongly suggest you place it seventy-five feet or more from any area where there will be significant human activity. The denser the canopy around the box, the better your chance of attracting a barred owl. Heat buildup in boxes exposed to direct sun is a major threat to owls in the South. Try to find a spot that will protect them from direct sun and consider adding vents to the top of the back panel. Raccoons are also a major threat to barred owl eggs and very young owlets. The following two measures will minimize the risk: (1) Complete your work in the fall and stay away from the tree. Raccoons look for food where they smell the scent of humans. (2) If raccoons are plentiful in your area, encircle the trunk of the tree with a sixteen inch band of aluminum flashing.

Waiting for the Owls: I have known people who put up owl boxes that were never occupied and others who attracted owls the first year (as I did). Your success will depend on nest placement and on the availability of homeless owls in your neighborhood. You can, however, be sure that the owls in your area will find it very quickly. Whether they move in next spring is another question. Good luck.

While You're Waiting: If you would like to see this nest box in action with a real family of barred owls, you might enjoy the OwlCam DVD. It is a feature length movie that captures all of the action of a successful nesting season through hidden cameras located both inside and outside the nest box. The DVD titled OwlCam, The Hidden World is now available at Amazon.

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