In order to prevent disease or the passing on of parasites, it is a good idea to clean out nest boxes after they’ve been occupied. In the fall, after the last brood of eastern bluebirds or tree swallows has flown the coop, many nest box owners often clean them out in preparation for the next summer’s residents, but some wait until spring. This habit of waiting provides white-footed and deer mice (and occasionally flying squirrels) with a ready-made winter shelter and/or larder.
Feathers incorporated into the pictured grass nest indicate that tree swallows once occupied this nest box. After the last of the avian nestlings had fledged, mice moved into the box. After constructing a roof over the nest, the mice succeeded in renovating the former bird nursery into a winter mouse house. The remaining space inside the box served as a larder for nearby high-bush cranberries.
Unfortunately for the mice, but fortunately for the swallows or bluebirds that will reside here this summer, the responsible nest box owner dutifully cleaned out the nest box this spring, in accordance with avian-mammalian timeshare policies. (Thanks to Jim Lafley for the use of his photo.)
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