Eastern rockhopper penguin Eastern rockhopper penguin The eastern rockhopper penguin ("Eudyptes chrysocome filholi") although genetically different is still often considered a subspecies of the southern rockhopper penguin. This species of penguin is also known to be one of the smallest species of penguins they are approximately 45–55 cm in length, and weighing 2.2–4.3 kg. The adult eastern rockhopper penguins feed on small fish, octopus, squid, and krill-like crustaceans. The rockhopper penguin "Eudyptes chrysocome" is sometimes considered two species, northern and southern rockhopper penguin, after research published in 2006 demonstrated morphological, vocal and genetic differences between the two populations. Molecular datings suggest that the
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