Owl Box 2.0
By Mike Coll, Preserve Manager
Shortly after writing about the success I was having with a Screech Owl box that I installed behind the springhouse at Hildacy Preserve, I encountered a setback. Squirrel intrusion! My first attempt to prevent squirrels from taking over the box had consisted of a 14-inch-wide piece of metal flashing wrapped around the tree trunk both above and below the box. This seemed to deter those pesky intruders for the better part of a year, but the persistence of squirrels can never be doubted.
At some point in mid December, a squirrel figured out that he could jump from above the flashing, land on the top of the box (which is also covered in metal to prevent claws from gripping), and somehow contort himself into the entrance hole. At that time I had seen the owl sitting in the opening of his box every evening for a month straight and then one night he was not there and it was the next day I first noticed a squirrel coming out of the box. Futilely I tried to shoo the squirrel from the box and, in response, the squirrel simply jumped from a height of 15 feet (about 30 times his body length!) to the ground and ran away- sure to return once I had moved on. Once the squirrels had entered the box the owl did not return. Among other things, squirrels almost immediately fill their nest cavities up with leaves and overall they are terrible roommates. Squirrels also outweigh Screech Owls by a fair margin (Screech Owls are only 7-10 inches tall).
I knew that the only thing to do was to take down the box, clean out the squirrel bedding, put more flashing up on the tree, and try again. However, upon taking the box down I found that there would be more to this project because the box (which was originally a converted Wood Duck box) had rotted through and the entrance was badly chewed by squirrels and so the project would truly have to start from scratch.
I began again with a box of roughly the dimensions described here. In an attempt to make this new box seem familiar to the old one, I replicated the particular structure of the previous entrance.
Since the first box (version 1.0) was originally a Wood Duck box, it had a four-inch entrance hole cut in it rather than a three-inch hole (the size preferred by owls.) To remedy this, I’d cut a three-inch hole in a separate piece of wood and attached it the front of the box over the larger hole. I had seen the owl spend a great deal of time sitting in that “stepped” opening. So, in the new box I again made a four-inch hole and covered it with the same piece of wood I had used on the entrance of the first box. I have no idea if things like this are helpful or not but it seemed sensible to try to keep as many factors constant as possible.
I also built a perch onto the front of the new box. My hope is that, if an owl ever raises young in the box, the newly fledged birds will have a place from which to start their first flights. This was something I had attempted on the old box but the perch I built was not strong enough and soon fell down. The new perch is made from a real tree branch that I attached at two points. I also painted the box dark brown to protect it from the elements. I covered the roof and front of the box with metal flashing to help water to run off.
Another important aspect of this box is the bracket that I built to anchor it to the tree. Since the box is going 15 feet up in a tree you can imagine the difficulty of trying to stand on a ladder, hold a screw gun in one hand and the box in the other, and at the same time accurately drive screws.
An simple bracket can be made using wood strips that are cut at complimentary angles. The bracket (which is much smaller than the box) can be more easily attached to the tree and the box is then hooked onto the bracket. The picture on the right shows the wood strips on the back of the box, the ones on the bracket look like the inverse of these.
The interior of the box also contains some features customized for the owl lifestyle. There is an interior perch that I bought from a pet supply store. This offers a place for the adults to sit while they feed young on the floor of the box. I also scraped a ladder of sorts into the wall below the entrance hole to offer footholds to help young birds climb out of the box. In the picture below you can also see the “stepped” entrance hole.
It was at about this point that I had the bright idea that I should put a camera inside the box since I was going to all this trouble anyway! I did some research and found a very small camera that transmits a wireless signal and has the wide field of view and short focal length required in a bird box. It can also record audio and has infrared lights that allow it to illuminate the box at night without disturbing the owl. This camera can also be connected to a USB port allowing it to transmit a live video feed straight to a computer. Unfortunately, it’s produced only in the UK, which caused a host of technical problems that I will not bore you with. Suffice it to say, I figured it out eventually and the project continued.
To accommodate the camera system, I designed a weatherproof box that would sit on the roof of the owl box. I decided to power the camera with a series of long extension cords rather than deal with battery replacement. Here is a view of the interior of the camera box looking down from the top.
Looking up from the inside of the box (below the perch), the camera is visible.
Photo: Mike Coll
And the final product with the camera box sealed and painted on top. With everything in place, all that was left to do was set the box back on the bracket and hope that the owl would appreciate the hard work I had put in. Towards the beginning of February, I lined the bottom of the box with wood shavings (used as bedding by owls) climbed to new heights on my ladder to affix more squirrel baffles, and put the new box in place. Two days later I checked the video feed on my computer and found that the owl had returned and was resting comfortably inside the box.
For the rest of February and March, the owl, who is presumably a lone male, stayed in the box almost every day. In the evening, he spends about half an hour sitting in the box’s opening, taking in the last rays of sun and waking up before his evening hunt.
Most nights he can be heard calling for a mate from the entrance of the box. The linked video below captures his call. He starts off slowly then really gets going towards the middle. http://youtu.be/UNhUNK6oQW4
This video shows the owl preening his feathers and then leaving the box for the night. http://youtu.be/FBiWPF8MAAQ
But the saga continues! The camera I initially installed failed completely and I was forced to wait for a replacement from the company overseas. Last week I finally received the replacement and (on a day when the owl was not in the box) went up and swapped out the cameras.
This picture also shows most of the squirrel baffling above and below the box.
Now the camera is functional and the owl has been visiting the box regularly. I have not yet seen him with a mate but he continues to call. Mid April is the beginning of breeding season for Screech Owls in this part of the country so it is possible that in the near future we will have a pair to watch.