Zygodactylous feet

 Most perching birds have three forward facing toes and one rear facing toes - so called anisodactyl feet. Some species such as owls, woodpeckers, cuckoos and parrots have what is termed zygodactyl feet where two toes face forward and two toes face backwards. In the case of woodpeckers it helps them grip when climbing and with owls it helps holding prey whilst in parrots it gives them a huge amount of dexterity when holding and eating food. As a ringer the commonest  zygodactyl feet  I see is in the Greater Spotted Woodpecker such as this bird in the photo below. This adaptation, along with their stiff tail feathers makes then perfectly adapted to climbing tree trunks.

I've also been lucky enough to ring a few Owls and the same arrangement of two forward and two rear facing toes can be seen in the photo of a Little Owl ringed in our garden below. ou can see from the talons how this adaptation allows them to grip prey. With two forward and two rear facing talons imbedded in flesh an unfortunate rodent is unlikely to escape

Although I've not been fortunate enough to ring any parrots on any of my Australian trips I've managed to photograph a few but very few of the photographs show the toe arrangement. I manage to find one of a Rainbow Lorikeet I photographed in Merimbula a few years ago that shows two forward facing toes but not the two rear ones! 

Swifts have pamprodactyl feet where all four toes face forwards. This adaptation allows them to cling to vertical surfaces to roost.

Its incredible how different families of birds have evolved to have different arrangements of toes suited to their lifestyle and feeding behaviour.