Tuesday, 11 December 2007
Anatomy, structure: feet
Like most tree-dwelling birds, woodpeckers have zygodactyl feet. That is, they have four toes arranged in the so-called "yoke" formation of two toes (digits 2 and 3) pointing fowards and two pointing backwards (digits 1 and 4). However, this yoke formation (a kind of "X" shape) changes when woodpeckers climb as their feet are rotated with digit 4 usually held in a lateral position. In Europe Three-toed Woodpecker is the exception (hence the name) as it has completely lost digit 1. In fact, all woodpeckers are "three-toed" in terms of using their toes, as digit 1 is very short and almost redundant. All woodpeckers have relatively short legs and feet and their toes are tipped by strong claws. These adaptations are related to their arboreal lifestyle. The sharp claws are ideal for gripping tree surfaces, even very smooth bark, as in this photo of a Middle Spotted Woodpecker (taken in Hungary by Dan Bastaja).