The western screech owl is a small owl found throughout western North America. They are mostly active at night and feed on insects, small mammals, and reptiles. Western screech owls nest in natural tree cavities, but will also readily use artificial nest boxes placed in suitable habitat. When installing a nest box for western screech owls, there are some key factors to consider regarding placement and design to increase the chances of the box being used.
Where to Place a Western Screech Owl Nest Box
When deciding where to put up a western screech owl nesting box, the three main factors to consider are location, height, and orientation:
Location
Ideally, the nest box should be placed in an area near open fields, meadows, or other open areas that provide good hunting grounds for the owls. Western screech owls prefer habitat edges rather than deep forest interiors. Place the box within 100 yards of open habitat. Avoid residential yards or other areas with high human activity.
Good locations include along the edge of a meadow, near a grassy field adjacent to a wooded area, along a creek corridor bordered by trees, or along the edge of a park. The owls need trees nearby to provide cover during the daytime when they roost. Having open areas nearby provides habitat for the small mammals and insects the owls prey on.
Height
Mount the nest box on the trunk of a large tree, high enough to be safe from predators but low enough to be accessible to the owls. An ideal height range is between 10 and 30 feet above the ground.
Screech owls are small and agile flyers so they have no problem entering a box mounted fairly high up. Installing the box at least 10 feet high helps protect the owls and their nestlings from predators like raccoons, snakes, and house cats. But don’t mount the box more than 30 feet high, as very tall boxes may be difficult for the owls to access.
Orientation
The entrance hole should face an open area away from prevailing winds and rains. Face the entrance hole southeast to take advantage of the morning sun. This helps warm the interior of the box which is beneficial for egg incubation and rearing nestlings.
Avoid pointing the entrance toward the northwest where cold winds or storms are more likely to blow into the hole. And never place the hole on the top only on the front facing side.
Nest Box Design
In additional to proper placement, the design of the nest box must meet the needs of western screech owls:
Size
The interior floor dimensions of the box should be around 8×8 inches, with an internal height of 12-15 inches. This provides enough room for the adult owls and their young. The entrance hole should be 3-4 inches in diameter.
Ventilation & Drainage
Proper ventilation and drainage will help keep the box dry and prevent overheating. Drill ventilation holes near the top of the box under the roof. Add drainage holes or slots in the box floor to allow rain to pass through.
Accessibility
As mentioned above, install the box at a height that can be reached by the owls. Also, ensure the front panel with the entrance hole can be opened for periodic cleaning and monitoring. Screw the panel in place rather than nailing it to allow for removal.
Roof Overhang
Add a sloped roof that extends out past the entrance hole by several inches. This will help repel rain and prevent wetting of the interior cavity.
Substrate
Cover the floor with 2-3 inches of wood shavings, pine needles, wood pellets or other organic material to provide a suitable substrate for the owlets once they hatch. The female will not add nesting material to the box prior to egg laying.
Perches
Consider adding an exterior perch next to the entrance hole to provide a landing spot for the owls. Make sure the perch does not obstruct the entrance.
When to Install Western Screech Owl Boxes
To increase your chances of attracting western screech owls, have the nest boxes installed before the beginning of breeding season.
In most parts of their range, breeding gets underway in March and April. Males begin establishing and defending their nesting territories in late winter. Having the boxes already in place by February will allow the owls sufficient time to find and claim them.
Avoid installing boxes or disturbing potential nest sites during the actual breeding season of March through June.
Box Occupancy Rates and Maintenance
Even when properly sited, western screech owl boxes may not be used the first year. Allow at least two breeding seasons before judging the success of a box. Occupancy rates of 25-60% after 2-3 years are typical for screech owl boxes installed with favorable habitat characteristics.
Plan to do annual maintenance on your owl boxes before the start of each breeding season. This includes:
– Removal of old nesting material
– Addition of fresh substrate
– Inspection for damage with repairs as needed
– Removal of any invading insects like bees or wasps
Also avoid opening occupied boxes during breeding season to prevent accidental abandonment. Most monitoring should be done through external observation only once eggs have been laid.
With proper placement and maintenance, western screech owl boxes can provide critical nesting habitat while also creating opportunities to observe these fascinating birds near home. Watching adults carry prey to the nest or hearing begging calls of the nestlings are memorable experiences for many owl box landlords.
Conclusion
Providing western screech owl nest boxes is an effective way to attract these small owls and provide nesting habitat. By mounting boxes in suitable locations about 10-30 feet high on tree trunks near open hunting areas, you can increase your chances of occupancy. Face the entrance hole away from prevailing weather and orient it to the southeast. Follow box designs that offer the right interior size, ventilation, drainage, and accessibility for screech owls. Install boxes before breeding season and do annual maintenance to keep them in proper condition. With a good setup, western screech owl boxes can yield rewarding results in being able to observe the breeding behaviors and raising of young by this cavity nesting species.
