Owl Nest Boxes

BARRED OWL NEST BOXES

  • SPECIAL NOTE: In the Pacific Northwest, Barred Owl boxes should not be placed in areas where they may out-compete the less aggressive Spotted Owls

  • Nests in large tree cavities within year-round hunting territory

  • Prefers sites with well-developed understory

  • Nest trees average over 20 feet tall with a diameter greater than 18 inches

  • Mount nest box 15-30 ft above the ground


    Shelter: Usually roosts during the day high in trees in wooded areas with a closed canopy that provide shade during hot days and shield owls from harassment by crows.
    Other: Clearing and fragmentation of large forest patches creates open habitat more suitable for Great Horned Owls, which will prey upon Barred Owls or drive them from their territory.

    SPOTTED OWLS
    The Northern Spotted Owl is found in Washington, Oregon, Northern California and British Columbia. The majority of the owls live west of the Cascade Mountains. Spotted owls nest in old growth, undisturbed mature forests, but also use mixed ages of forest for foraging and roosting. The male Spotted Owl selects the nest site—normally in a dense section of old forest, well protected from open sky by a dense tree canopy. Pairs may reuse a nest site over many years, though many pairs may not nest every year. The Washington Department of Fish and Wildlife is currently tracking 1,044 Spotted owl sites.The male Spotted Owl probably selects the nest site—normally in a dense section of old forest, well protected from open sky by a dense tree canopy.

BARN OWL NEST BOXES

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The important elements of a barn owl nest box are roominess to accommodate the species's large broods and seclusion from predation. Although barn owls have used a variety of designs, the style shown here has proven successful when placed in a variety of situations.

Construction is simple. Use exterior plywood if the box is to be placed in an exposed situation. Approximately nine drain holes, 1/4 to 1/2 inch in diameter, should be spaced throughout the bottom. Cover the bottom with 1 or 2 inches of wood shavings, as barn owls place no nest material.

Installation

Barn owls prefer to nest in buildings, and boxes should be installed high to lessen human disturbance and the dangers of predation from snakes, raccoons and cats. If placed in a barn, the front should face into the barn. The back can be nailed flat to the barn. Usually, a brace or stud can be located on which to secure the box firmly along one side. Metal straps attached on the back can be bent to hang the box in a barn or inside a silo. In some regions, barn owls use boxes that are simply wired in place high in a large tree.

The most productive site for a barn owl box is where individuals have been seen. The best localities are rural. Areas where there are open grasslands and crop fields and where grain spillage results in high mouse populations are especially suitable for nesting barn owls.

Biology

In the Puget Sound area barn owls are permanent residents. Their clutch of five to ten white eggs will produce a varying number of the young, depending on availability of prey. Incubation requires three weeks. The young, which vary in size due to their hatching dates, fly at about seven weeks of age. Barn owls often nest in the same site repeatedly.

Barn owls are considered to be our most beneficial owl, owing to their appetite for animal pests. One once was observed delivering 16 mice, three gophers, a rat and a squirrel to a nest within 25 minutes. The barn owl is found worldwide, nesting almost totally in buildings in the Old World and in hollow trees and burrows in much of the western United States. Throughout much of its range, the barn owl's numbers are thought to be limited by the availability of suitable nest sites.

EASTERN & WESTERN SCREECH OWL, NORTHERN SAW-WHET, BOREAL OWL, AMERICAN KESTREL

NEST BOXES

  • Owls do not build a nest

  • To mimic the inside of a natural cavity, put some wood chips (do not use cedar or sawdust) about an inch deep, but not too much

  • Mount box 10-30 feet above the ground

  • Face box entrance Southwest to Northeast

  • use untreated wood - fir, white pine, cedar (weathered wood is also recommended)

  • When mounting on a tree be sure the tree is as wide or wider than the nest box

  • if installing multiple boxes space at least 1000 feet apart

  • The plan below uses white pine 13/16 inches thick