I’ve added a couple of new bird feeders to my songbird catering service this year and while I was setting the shepherd’s hooks in our meadow I remembered I needed to mount the old roosting box my Dad and I built probably 30 years ago. What is a roosting box you ask, and why should you be thinking about setting at least one out in your yard?
While anyone with bird feeders knows there are lots of cute little guys hanging around for that free lunch, have you wondered where do they go at night to sleep, especially in very cold weather? In cold weather songbirds eat constantly during daylight hours to sustain their energy. At night they expend a lot of that energy fluffing their feathers and shivering to keep warm until dawn.
Often thick evergreens and other vegetation fail to provide enough protection for the smaller birds trying to get through a cold windy night. Though they crowd together for warmth, many birds become seriously dehydrated and freeze to death. Mortality is typically highest among the little birds such as bluebirds, wrens, chickadees, titmice and small woodpeckers. In a very bad snow storm with below freezing temperatures for more than a day or two, as much as 50% of smaller songbirds can perish. This is a real problem and yardeners can really help. These cute critters need their very own Motel 6.
Traditional roosting boxes are roofed, hollow boxes outfitted inside with pegged perches along their interior walls. Unlike birdhouses, which accommodate a nest, these boxes are only intended to provide shelter from severe weather for those cavity-nesting songbirds. They are accustomed to taking refuge in a protective hole in an old tree made by woodpeckers or tree injury. These days suitable protective hollow trees are removed from populated areas because they are unsightly, unsafe, or in the bulldozer’s path.
While the hole in a bird house is up towards the top of the box, a roosting box has the entrance hole set down low. Also unlike birdhouses they do not have vents or drainage holes, so the critical warm air generated by the roosting birds is retained. So if you have a roosting box on your property, the smaller birds, stuck in cold weather, can roost together in small groups to share body heat. In one documented case, 31 winter wrens were observed to fit inside an unused nesting box only 6 inches square!
Buying Roosting Boxes
There are six Wild Birds Unlimited stores in metro Detroit offering a number of roosting boxes ranging from $10 to $45 (www.wildbirdsunlimited). Duncraft offers an interesting box that allows you to flip the front wall so the hole is high during the season and used as a nesting box or flip it so the hole is low make the device a roosting box in the winter (www.duncraft.com, $45).
Building Roosting Boxes
If you are just a little bit handy, roosting boxes are easy to build. I have complete instructions with illustrations on my web site at www.yardener.com, placing “roosting box” in the search window. A 10 inch by 1 inch pine board 12 feet long is sufficient for one box. Perches for the interior are ¼ or 3/8 inch dowels. You will need a hand drill, a saw, a jigsaw (or hole saw), and a screwdriver.
It is a good idea, but not essential, to add a coat of exterior, dark colored paint on the outside of a roosting box to encourage the absorption and retention of daytime heat. Also a coat of varnish on exterior surfaces will extend the life of the box. Renew the coat of varnish each year. As with birdhouses though, never varnish or paint the inside of the roosting box; the birds won’t use it.
Mount roosting boxes 8 to 15 feet off the ground in trees or on buildings. A good place is in a mature pine tree where the foliage buffers the wind of the winter storms. It is best to mount the box in a spot that is easy to reach for cleaning. In any case, orient the entrance toward the south, away from prevailing winter winds. Be sure to locate it where accumulations of bird droppings will not be a problem.
Turn Birdhouses Into Roosting Boxes
I got a wonderful tip from Bill Thompson, editor of the wonderful Bird Watcher’s Digest (www.birdwatchersdigest.com $20 for year’s subscription). You can make every bird house into a roosting box by covering the ventilation holes on the sides near the top of the box with that gray clay-like corded material called Mortite; used to seal drafty windows for winter (available in any hardware store); then remove it in the spring.