Roosting Boxes: Building a home for the winter – The Couchiching Conservancy
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A much better idea is to either build or purchase a structure especially suited for winter use–a roosting box, which is designed to retain heat and avoid drafts. These roosting boxes can be as plain or fancy as you like, depending on your creative bent! It is best however if the box is much higher than a nest box–18-25″(46-64 cm) high boxes are ideal. Entrance holes are placed at the front bottom rather than at the top, so that warm body heat will rise to the inside top. Dowels are inserted in the walls in an offset pattern to accommodate roosting and to keep droppings from falling on any bird below. Any cracks in the exterior can be caulked or filled to keep the inside warm air from escaping. Although many birds do die during the cold winter months, the chances of survival are greatly increased if birds have better shelter.
Full plans can be found on the internet. I spent a couple of hours one morning last week making this roosting box, patterned after swallow houses I have been building for many years. The materials used were remnants of a recent fence building project.
Look through that lumber scrap pile you have out back. Make a plan, and then invite your children, grandkids or neighbour’s little ones for a bird roosting house building event some Saturday morning. It has all the makings of a great party!â€
http://www.couchichingconserv.ca/roosting-boxes-building-a-home-for-the-winter/