 Arboreal woodpeckers , which depend on their tails — particularly the strong central pair of rectrices — for support while they feed , have a unique tail moult . Rather than moulting their central tail feathers first , as most birds do , they retain these feathers until last . Instead the second pair of rectrices ( both R2 feathers ) are the first to drop . ( In some species in the genera Celeus and Dendropicos , the third pair is the first dropped . ) The pattern of feather drop and replacement proceeds as described for passerines ( above ) until all other rectrices have been replaced ; only then are the central tail rectrices moulted . This provides some protection to the growing feathers , since they 're always covered by at least one existing feather , and also ensures that the bird 's newly strengthened tail is best able to cope with the loss of the crucial central rectrices . Ground @-@ feeding woodpeckers , such as the wrynecks , do not have this modified moult strategy ; in fact , wrynecks moult their outer tail feathers first , with moult proceeding proximally from there . 
