An animal identification device (40) comprising a metal ear tag (12) that has a transponder housing secured thereto using an overmoulding step. The transponder housing is retained within a frame provided by the metal ear tag during the overmoulding process. The overmoulding process provides an outer cover (30) which encases the transponder housing to secure it in place. The outer cover does not project widthways beyond the metal ear tag, which increases the durability of the ear tag. The metal frame does not impede communication with the transponder, since the transponder is encased in plastic, not metal.
