Most residential and rural dwellers don’t enjoy rats, mice and ground squirrels setting up shop on their property, so they often resort to poisons to control the rodent populations. While those products succeed in getting the job done, they can also be deadly for birds that prey on rodents.
When a rodent eats a poison such as a second-generation rodenticide, it can still survive for several days before it succumbs. In its compromised state, the rodent becomes even more vulnerable to sharp-eyed raptors like barn owls. The owl eats the poisoned rodent and in short order becomes poisoned itself, leading to debilitating illness or death. Hibbert Lumber in Davis, CA, who donated the wood used in this video, in 2015 after they removed second-generation rodenticides from their store shelves completely. To see that happen on a large scale, the organization has been working with consumers and policy makers.
An owl box is a great alternative to poisons because it draws barn owls into your neighborhood and puts them in charge of your pest control. Not only are you not harming raptors; you’re actively supplying them food!
The box is divided into two chambers so that babies can be nurtured on one side without risk of falling out of the tree. The other side has an entry/exit hole for the grown owl. There’s a hatch on the babies’ side so that the box can be cleaned out during the season when owls are least likely to be there — usually around October and November in Northern California, where the UC Davis School of Veterinary Medicine’s is located.
Build your own owl box! Just follow the steps in the video above.
- 2 C-clamps
- Contractor square
- Tape measure
- Table saw (preferred) or skill saw
- Small hinge with screws
- Small door latch or hook
Start with a 4’ x 8’ sheet of ¾” plywood and cut it to the following:
- top: 26 x 21
- bottom: 24 x 19
- front: 24 x 20
- back: 24 x 17
- sides: 17 x 17 & 20 (3-inch pitch)
- interior divider: 17” x 17” & 5” (Most of the interior divider spans from top to bottom, but about ¼ of it drops to 5” high so that babies can’t cross from one side to the other, but a grown owl can.)
For instructions on mounting your owl box, visit
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Justin Cox is content marketing manager for the UC Davis One Health Institute and the Karen C. Drayer Wildlife Health Center.