You searched for: “zygodactyly
zygodactyly (s) (noun) (no pl)
An arrangement of digits in birds, with two toes facing forward (digits two and three) and two back (digits one and four): Zygodactyly is most common in arboreal species, particularly those that climb tree trunks or clamber through foliage.

Zygodactyly occurs with woodpeckers, flickers, nuthatches, and parrots.