Answer: woodpeckers

AnswerCrossword Clue
WOODPECKERSHammering critters
woodpeckersWOODPECKER, any of a family of birds in the order Picariae, remarkable for modification of the skull and bill enabling the latter to be used to drill holes
woodpeckersA bird with a strong bill and a stiff tail, that climbs tree trunks to find insects and drums on dead wood to mark territory