The annealing of implantation induced lattice damage in AlN, GaN and InN was studied by means of the perturbed angular correlation (PAC) technique using the PAC probe 181Hf(181Ta). In all three lattices substantial fractions of the probe atoms occupied substitutional lattice sites after annealing. A detailed investigation of the changes observed during isochronal annealing indicates differences in the recovery process. In GaN the trapping of a unique defect, possibly a Nitrogen vacancy, in an intermediate temperature range was found.