 Both the shag and the sheathbill are endemic to Heard Island.A further 28 seabird species are recorded as either non-breeding visitors or have been noted during 'at-sea surveys' of the islands.All recorded breeding species, other than the Heard Island sheathbill, are listed marine species under the Australian Environmental Protection and Biodiversity Act (1999, four are listed as threatened species and five are listed migratory species.