As ancient, hollowed trees disappear in England, one researcher and his team are engineering prosthetic nests to provide an alternative home for endangered birds.

Different birds look for different nest box styles and entrance sizes. Smaller songbirds like chickadees and wrens prefer snug entrance holes around 1 to 1.5 inches, while larger birds need bigger ...

The males of the species prepare for mating season by excavating nests for the approval of the females — and even other birds and animals.