Zygodactyl(e)Having two toes facing forwards and two backwards, instead of the more usual arrangement where three face forwards and one backwards. Zygodactyle feet are found in the woodpeckers (family Picidae) as an aid to climbing and perching vertically on the trunks of trees.
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From Peter Weaver's Birdwatcher's Dictionary
Copyright © 1981 by Peter Weaver