Annet, Isles of Scilly have nationally important breeding populations. The storm–petrel breeds amongst the boulders of the more stable storm beaches. The largest population of Manx shearwater ("Puffinus puffinus") in the islands breed here and the other annual breeding species are puffin ("Fratercula arctica"), greater black-backed gull ("Larus marinus"), razorbill ("Alca torda"), kittiwake ("Rissa tridactyla"), fulmar ("Fulmarus glacialis"), herring gull ("L. argentatus") and shag ("P. aristotelis"). Common tern ("Sterna hirundo") breed on the island most years as do cormorant ("Phalacrocorax carbo") and very rarely Arctic tern ("S. paradisaea"). Annet has long had a reputation for being the best island for breeding birds and Jessie
Cape Byron Marine Park identifies the migratory little tern "(Sterna albifrons)" and the Beach stone-curlew "(Esacus neglectus)" as endangered. Seabirds that utilize the Cape Byron Marine Park are the providence pretal "(Pterodroma solandri)", flesh-footed shearwater "(Puffinus carneipes)", and the masked booby "(Sula dactylatra)" which are protected under the National Parks and Wildlife Act 1974. Although no invertebrates have been identified as endangered or vulnerable, it is important to acknowledge that there are a plethora of invertebrates within the Cape Byron Marine Park which are critical to the health of the local ecosystems. These include a variety of molluscs such as the gold ring cowries