For those who have travelled by boat across the Bass Strait, you may be familiar with the power, strength, and beauty it embodies. This remarkable region of fierce seas and remote rocky islands is of immense importance for many Australian and migratory seabird species.
The broad land bridge known as the Bassian Plain, once serving as a passageway for First Nations People to travel between Lutruwita/Tasmania and Victoria, now lies submerged at the bottom of the Bass Strait. Between approximately 14,000 and 10,000 years ago, after the melting of glaciers during the last Australian ice age, rising sea levels led to the formation of the Bass Strait. This geographical shift created a barrier for the Palawa and mainland First Nations People, hindering connection between the two regions. This body of water transformed the environment and biodiversity of the surrounding area, with marine life populating the waters below. Seabirds, which may have previously bred in various locations along the old coastlines of the land bridge, now make use of the Bass Strait islands to breed and nest.
A shy albatross soars over the Southern Ocean. The shy albatross is a threatened species which breeds only on three islands off Lutruwita/Tasmania. Photograph by Ed Dunens. CC BY 2.0.
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With thanks to
The Institute of Marine and Antarctic Studies (IMAS).
The interconnection between land and sea is fundamental to island ecosystems. As the sea engulfed the Bassian Plain, the highest peaks emerged as islands, becoming sanctuaries and vital breeding grounds for seabirds seeking shelter from mainland predators. Below the surface, a thriving underwater world teems with ocean life – an abundant smorgasbord for seabirds. Prey species such as squid, schooling fish and krill entice the seabirds in the surface waters to forage and fill their bellies for their hungry chicks.
Albatrosses, petrels and Australasian gannets, prominent species on these islands, play critical roles as predators in the marine ecosystem. With a single egg laid per year, these birds dedicate all their energy to foraging and nurturing their chicks.
Albatross Island Nature Reserve, in the west of Bass Strait, hosts one of three shy albatross populations endemic to Lutruwita. This charismatic, socially monogamous bird is a threatened species, so finding refuge on Albatross Island is incredibly important for their conservation as they have very slow reproductive rates, and their chicks take seven years to reach sexual maturity.
Shy albatross chicks take seven years to reach adulthood. An adult albatross feeds a chick on Albatross Island in the Bass Strait. Photograph by Demelza Wall. Image taken under permit. CC BY-NC-ND 4.0
Albatross Island Nature Reserve, in the west of Bass Strait, hosts one of three shy albatross populations endemic to Lutruwita/Tasmania.
Meanwhile, Black Pyramid Rock Nature Reserve, south-west of Albatross Island, houses the largest colony of Australasian gannets in the Bass Strait and one of only three in the whole of Tasmania. The location of these islands within the Bass Strait provides optimal conditions for large seabirds, enabling them to use the wind gradients for dynamic flight while foraging. Their unique, long, slender wing morphology allows them to effortlessly soar over vast distances, conserving their energy for foraging and chick rearing.
Babel Island is home to the largest short-tailed shearwater (commonly known as muttonbirds or yula) rookery in Australia. It is dotted with up to 3 million burrows! Short-tailed shearwaters breed exclusively in Australia from September to April, undertaking an annual migration that spans 15,000 kilometres from Australia into the northern hemisphere, where they end up near the coast of Alaska before returning to breed. Muttonbirds are abundant seabirds, reaching sexual maturity between the ages of 4 and 8 years. They lay their eggs in burrows that can extend up to two metres in length, excavated in soft sediment, often using the same burrow as the year before. Short-tailed shearwaters forage by landing on the water surface and then diving into the water, propelled by their agile wings. Their conspicuous moaning, cooing, and wailing amblings during breeding can make quite a spectacle for anyone passing by.
The slender wings of the Australasian gannet allows them to effortlessly soar over vast distances. Black Pyramid Rock Nature Reserve, south-west of Albatross Island, houses the largest colony of Australasian gannets in the Bass Strait. Photograph by Ed Dunens. CC BY 2.0.
An Australasian gannet hunts for fish. Photograph by Ed Dunens. CC BY 2.0.
The short-tailed shearwater, also known as muttonbird or yula, forages by landing on the water surface and then diving into the water. Photograph by Ed Dunens. CC BY 2.0.
Meanwhile, Cat Island a neighbour to the east of Babel Island, serves as another, smaller but bustling breeding ground for many seabirds. These include little penguins, which are cute and curious and magnificent swimmers in the Bass Strait, silver gulls – the squawking, ubiquitous fish and chip thieves of Australian beaches everywhere, pacific gulls – a larger and less common type of gull found mainly on Australian southern coasts, crested terns with their elegant black crests, pied and sooty oystercatchers, so distinctive with their bright red beaks, long legs and shy demeanour, and imperious-looking black-faced cormorants.
The Bass Strait islands hold profound conservation value in southern Australian waters. Whether you’re a frequent traveller of the Bass Strait or a first-time wanderer – be sure to pack your binoculars!
A pied and a sooty oystercatcher. Photograph by Ed Dunens. CC BY 2.0.
Babel Island and neighbouring Cat Island in the Bass Strait are bustling breeding areas for short-tailed shearwaters, silver gulls, pacific gulls, little penguins, crested terns, cormorants, and oystercatchers.
The ubiquitous silver gull breeds in the Bass Strait. Photograph by Envato Elements. All rights reserved.
Short-tailed shearwater, also known as muttonbird or yula. Photograph by Ed Dunens. CC BY 2.0.
Pacific gull. Photograph by Ed Dunens. CC BY 2.0.
Shy albatross chicks on Albatross Island in the Bass Strait. Photograph by Demelza Wall. Image taken under permit. CC BY-NC-ND 4.0.
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This story is subject to disclaimers, copyright restrictions, and cultural clearances. Copyright © Kiah Berglund, 2024.
Further reading
Bryant SL & Harris S (2020) ‘Overview of Tasmania’s offshore islands and their role in nature conservation’, Papers and Proceedings of the Royal Society of Tasmania, vol. 154, pp. 83-106.
Fromant A, Schumann N, Dann P, Cherel Y & Arnould JPY (2020) ‘Trophic niches of a seabird assemblage in Bass Strait, south-eastern Australia’, PeerJ, vol. 8, no. 8700.
Tasmanian Parks and Wildlife Service 2000, Small Bass Strait Island Reserves Draft Management Plan (2000) Department of Primary Industries, Water and Environment, Tasmania, available at https://parks.tas.gov.au/Documents/bassstraitpdf.pdf, accessed 5 June 2024.
