Barred owls are medium-sized owls native to North America. They get their name from the horizontal brown and white striping on their chest and belly feathers. Barred owls prefer to nest in the natural cavities of large trees, but suitable nesting sites have become scarce in some areas due to deforestation and loss of old growth forests. Installing artificial nest boxes can help provide additional nesting habitat for barred owls where natural sites are limited. Careful planning and proper box design are important for success.
Overview of Barred Owl Nesting Habits
Barred owls nest in cavities at least 9 inches across and with a minimum interior depth around 16 inches. The female owl selects the nest site and does most of the work excavating the cavity. Barred owls often nest in the same general area year after year. A typical clutch contains 2-3 eggs which are incubated by the female for 28-33 days while the male provides food. The young owlets leave the nest at around 4-5 weeks old but remain dependent on the parents for several more weeks.
Choosing a Good Nest Box Location
When deciding where to place an artificial nest box, look for areas of mature forest with large trees near water. Owls prefer quiet sites away from human disturbance. Face the entrance towards an open area with available hunting perches. Mount the box at least 15 feet high on the tree trunk to deter predators. Avoid areas near busy roads or trails. Consult your state wildlife agency for advice on the best sites in your region.
Nest Box Design Considerations
Several factors are important in constructing or selecting an artificial nest box suitable for barred owls:
Box Size
The interior cavity needs to be at least 8-10 inches wide, 8-12 inches high and 16 inches deep. This provides sufficient room for the adult owls and young.
Entrance Hole
The entrance hole should be around 6 inches in diameter. Make the hole at least 3 inches from the floor of the box so young owls cannot accidentally fall out.
Construction Materials
Use untreated, unpainted wood at least 3/4 inches thick. Avoid wood products with harsh resins. Rough-cut lumber provides good claw grip.
Rain Protection
Install a predator guard or overhanging roof to prevent water from entering the nest box. Leave the bottom untreated so it can decay and drain over time.
Ventilation and Climate Control
Drill ventilation holes near the top to prevent overheating. Face the box between northeast and southeast to avoid afternoon sun. Insulation is not necessary.
Access Panel
An access panel allows monitoring and cleaning out old nesting material after the nesting season.
Mounting Pole
Use a sturdy mounting pole or tree mount to attach the nest box firmly and deter predators. Metal flashing around the base prevents rodents and snakes from climbing up.
Sample Nest Box Design
Here is one sample design for a barred owl nest box using the recommended features:
Materials
– 3/4 inch untreated plywood
– 4×4 inch mounting pole pressure treated or metal
– 6 inch diameter PVC for entrance hole
– 3-4 inch screws or nails
– Waterproof wood glue
– Metal flashing
Cut List
– 1 Front Piece: 17 x 24 inches (entrance hole cutout)
– 1 Back Piece: 16 x 24 inches
– 1 Bottom Piece: 10 x 24 inches
– 2 Side Pieces: 16 x 10 inches
– 1 Top Piece: 10 x 24 inches (with ventilation holes)
– 1 Access panel: 10 x 8 inches
Assembly
1. Cut out all wood pieces according to the cut list.
2. Drill 8-10 ventilation holes in the top piece.
3. Glue and screw or nail the front, back, and sides together into a box shape leaving the top and bottom unattached.
4. Attach the bottom piece with screws, leaving gaps in the corners for drainage.
5. Cut a 6 inch circular entrance hole on the front centered about 6 inches from the bottom.
6. Attach the top piece with screws to create a sloped roof overhang on the front above the entrance hole.
7. Attach a wood access panel using hinges and screws on the side or back.
8. Paint the inside of the box with non-toxic wood preservative or leave unfinished.
9. Secure the finished nest box and mounting pole high on a suitable tree.
10. Add flashing around the base. Angle the entrance hole in the desired direction.
Maintenance
– Monitor the box during nesting season.
– Clean out old nest material after young have fledged.
– Make any repairs needed and re-apply wood preservative annually.
Conclusion
Providing artificial nesting boxes is an effective way to support barred owl populations by supplementing the declining availability of natural cavities. Careful planning of box placement, size, construction and maintenance will increase the chance of barred owls successfully using the nesting site. An excluded box with adequate room, weather protection, and sturdy mounting has the best opportunity to attract a nesting pair. With proper siting and care, a nest box can provide many years of habitat for barred owls.
