Treecreepers | Certhiidae

Boomkruipers | Agateadores

Small, brown-spangled birds that climb a trunk like a mouse, always from the bottom upward and in a loose spiral around the stem; at the top they let go and fly to the foot of the next tree to begin again. The tail is stiff and pointed, with strong shafts, and is set against the bark at every step as a third point of support, so the bird hangs back from the trunk and never climbs head-down. The bill is thin, long and curved like a pair of forceps and works into bark crevices after spiders, springtails, eggs and pupae; the toes are long and the claws strongly hooked. The nest is a platform of twigs carrying a cup of bark, moss and feathers, tucked behind a hanging plate of bark or in a narrow crack. To roost, a bird gouges an oval hollow in soft fibrous bark with its bill and presses into it head-inward, alone or, in frost, many at once. The voice sits very high, around six to eight kilohertz, high enough that older observers regularly miss the family altogether. The European species resemble one another so closely that call and song settle a record in the field more often than plumage does.