Photo Album – Hairy Woodpecker
A Hairy Woodpecker
) about to make impact on the trunk of a poplar (click to enbiggen). Visible is the nictitating membrane
which not only protects the eye from ejected particles, but also prevents the eye from leaving the socket due to the severity of the impacts. Woodpeckers have a multitude of adaptations that fit their lifestyle: zygodactyl
(four toes, two up, two down) feet on short legs for climbing vertical surfaces; a short, stiff tail for bracing the body and a tuft of feathers seen at base of beak, above (probably the source of its name, villosus
= ‘with soft hairs’) which protect the slit-like nostrils from debris entry. The bill is hard and chisel like, with a very long tongue with a barbed tip for extracting its insect prey. The brain is protected by its small size, its orientation within the thick-boned skull and by the fact that each strike has only a brief impact.
For more on woodpeckers:
Woodpeckers: barbed tentacles and the avoidance of brain injury (Tetrapod Zoology)
Protective ocular mechanisms in woodpecker [PDF]
Anatomy and evolution of the woodpeckers tongue.