Sometime in the last century, treecreepers made a discovery that changed their sleeping habits for good. Dating mainly from Victorian times, majestic redwoods from North America were widely planted as ornamental trees in parks and large estates throughout the British Isles. The bark is soft with a texture like cardboard. For the tree the spongy exterior acts as a protective fire blanket. Somehow, treecreepers chanced upon an alternative use as a deep pile mattress. Using their toenails, the birds scratch out a neat, body-sized hollow and flatten themselves against the trunk. Birds from a wide area converge on mature specimens and several may be found clamped on a single suitable tree. However, the species' ingenuity doesn't stop there. Over time, each makes not one hole but several encircling the trunk. This means that, depending on the direction of wind or rain, a bird will always have dry, draught-free overnight accommodation
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