Document ID: chunk:federal_register_of_legislation:F2022L00775:reg:4:p1
Version: federal_register_of_legislation:F2022L00775
Segment Type: reg
Provision Reference: reg 4 (pt 1/12)
Character Range: 10410–13423

4     Wildlife Conservation Plan for Seabirds

 Seabirds are a taxonomically varied group of nearly 350 bird species (around
 3.5 per cent of all birds) that depend on the marine environment for at least part of their life cycle (BirdLife International 2019). By convention, seabirds are defined as species in the families Phaethontidae (Tropicbirds), Hydrobatidae (Northern Storm-petrels), Oceanitidae (Austral Storm-petrels), Diomedeidae (Albatrosses), Procellariidae (Shearwaters and petrels), Spheniscidae (Penguins), Fregatidae (Frigatebirds), Sulidae (Gannets and boobies), Pelecanidae (Pelicans), Stercorariidae (Skuas) and Laridae (Gulls and terns). While seabirds vary greatly in their lifestyle and habitats, behaviour and physiology, they often exhibit striking convergent evolution, as the same environmental challenges and feeding niches have resulted in similar adaptations.
In general, seabirds are long lived, have delayed breeding and have fewer young than other birds do. Most species nest in colonies, which can vary in size from a few dozen birds to millions. Many species undertake long migrations, crossing the equator or circumnavigating the Earth in some cases. They feed both at the ocean's surface and below it, and even feed on each other. Seabirds can be oceanic, coastal, or in some cases spend a part of the year away from the sea entirely.

 Adaptation to the marine environment

Seabirds have evolved numerous adaptations to living on and feeding in the marine environment. The evolution of wing morphology of an individual species or family has been shaped by its ecological niche. Longer wings and low wing loading are typical of more oceanic species, while diving species have shorter wings (Gaston 2004). Species such as the Wandering Albatross (Diomedea exulans), which forage over large areas of ocean, have a reduced capacity for powered flight and are dependent on a type of gliding called dynamic soaring (where the wind deflected by waves provides lift) as well as slope soaring (Pennycuick 1982). Seabirds also almost always have webbed feet, to aid movement on the surface as well as assisting diving in some species.
The Procellariiformes are unusual among birds in having a strong sense of smell, which is used to find widely distributed food in a vast ocean (Lequette et al. 1989) and possibly to locate their colonies. Salt glands are used by seabirds to deal with the salt they ingest by drinking and feeding (particularly on crustaceans), and to help them osmoregulate (Harrison 1990). The excretions from these glands (which are positioned in the head of the birds, emerging from the nasal cavity) are almost pure sodium chloride.
Wildlife Conservation Plan for Seabirds 5
 Seabirds of Australia

 Diet and foraging behaviour

Seabirds have evolved to exploit different food resources in the world's oceans, and to a great extent, their physiology and behaviour have been shaped by their diet