Plates of meat, feet. Cockney Rhyming Slang. Google it!
Birds' feet take many forms and each has a descriptor depending on how many toes point forwards versus backwards, whether toes are fused or not etc etc. One of the most interesting is that of the woodpeckers. No surprise that they have peculiar feet as they spend most of their time suspended on the side of tree trucks. Rather than the "normal" arrangement of three toes forward and one backwards, most woodpeckers have two forward and two backward. The term for this is "zygodactyly" and their feet are called "zygodactylous"- zygo = paired from greek for yoke, and dactyl = finger or toe.
This image shows the foot of a female Downy Woodpecker. I've arbitrarily numbered the toes 1 through 4. As mentioned, a typical arrangement in birds is to have toes 1-3 pointing forward and 4 pointing back. This is the typical situation for example in the perching birds or "passerines". In the case of the Downy Woodpecker, toe-3 is turned back and points in the same general direction as toe-4.
One aspect of woodpeckers' feet I had not noticed until now is how the outer toes are so much bigger and more developed than the inner ones. Notice how big toes 2 and 3 are compared to 1 and 4. I would imagine a biologist has done a mechanical study of this to find out why woodpeckers' feet are the way they are. On first principles I would design them differently but who's to argue with evolution?!
And then there are 3-toed woodpeckers!







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