Northern rockhopper penguin Island in the south Atlantic Ocean. The rockhopper penguin was split into three distinct subspecies in 1992; the southern, ("E. c. chrysocome"), eastern ("E. c. filholi") and northern rockhopper penguin ("E. c. moseleyi"). The three subspecies are distinguished by differences in the length of the tassels of the crests, the size and colour of the fleshy margin of the gape, colour pattern on the underside of the flipper and differences in the size of the supercilliary stripe in front of the eye. Additionally, the northern rockhopper penguin is larger than the other two subspecies. Proof that the three subspecies were
Bird vocalization and prevent an energetically costly fight . In birds with song repertoires, individuals may share the same song type and use these song types for more complex communication. Some birds will respond to a shared song type with a song-type match (i.e. with the same song type). This may be an aggressive signal, however results are mixed. Birds may also interact using repertoire-matches, wherein a bird responds with a song type that is in its rival's repertoire but is not the song that it is currently singing. This may be a less aggressive act than song-type matching. Communication through bird