At the (110) surface of a III-V semiconductor, the atoms are arranged in zigzag chains. If a surface vacancy is to move to a nearest-neighbor sublattice site, it must migrate within these chains. The scanning-tunneling-microscopy observations reported here, however, demonstrate that As vacancies on GaAs(110) prefer to move between zigzag chains. This phenomenon can be understood in terms of simple bond-breaking and rebonding arguments, and from barrier heights calculated using constrained molecular dynamics.