Every spring, millions of short-tailed shearwaters return to their breeding colonies off Australia's southern and south-eastern coasts. Also known as the mutton bird, the short-tailed shearwater is one of Australia's most common seabirds. 

The migration journey of the shearwaters is incredible. They fly about 16,000 km to feed near Alaska during Australia's winter. In early April, the adults begin their migration. The fledglings leave three weeks later with no parental guidance.

Phillip Island in Victoria hosts one of the world's largest colonies of short-tailed shearwaters, with around 1.4 million birds. The shearwaters arrive on the island in spring. They spend the summer caring for their single chick in a sand dune burrow.

When fledglings are ready to leave their nest at night, they face a dangerous challenge. 

Artificial lights attract the fledglings as they embark on their first journey to the open ocean from their nests. The glare and light spill of street lighting can disorientate birds and affect their navigation. It attracts them towards roads where they are at risk of being struck by vehicles. 'Fallout' is the term used to describe this phenomenon. Some fledglings make it to the ocean but are then drawn back to land by the coastal lighting. Once grounded, the young birds are also at risk of becoming prey.

In response to the deaths of fledglings, a series of studies by the Phillip Island Nature Parks has provided valuable information for artificial light management on the island. 

This research is now used in practical conservation initiatives in partnership with Bass Coast Shire Council, Regional Roads Victoria, SP Ausnet and the local community. The Parks also runs a Shearwater Rescue program to help the shearwaters take off safely.

They turn off the lights on the bridge to the island and place signage for motorists to lower speed limits during the peak of fledging departure in late April. Since the program began in 1999, thousands of birds have been saved from the roads as they attempt to fly.

"Infrastructure and development are one of the biggest threats to biodiversity. It is crucial to preserve the integrity of the natural skylight combined with habitat restoration and reintroduction of nocturnal native species. These initiatives show that reducing light pollution and better traffic management can mitigate artificial light-induced mortality of this iconic seabird."

- Dr Andre Chiaradia, Phillip Island Nature Parks.
Image credit - Phillip Island Nature Parks

Discover more about the State of the Marine and Coastal Environment 2021 Report

You can read more about the impacts of light pollution in the State of the Marine and Coastal Environment 2021 Report