  We map the problem of the orbital excitation (orbiton) in a 2D
antiferromagnetic and ferroorbital ground state onto a problem of a hole in 2D
antiferromagnet. The orbiton turns out to be coupled to magnons and can only be
mobile on a strongly renormalized scale by dressing with magnetic excitations.
We show that this leads to a dispersion relation reflecting the two-site unit
cell of the antiferromagnetic background, in contrast to the predictions based
on a mean-field approximation and linear orbital-wave theory.
