AUSTRALIA’S most numerous seabird, the Short-tailed Shearwater, started arriving in modest numbers at Phillip Island on Monday, September 27 this week.

Depending on prevailing winds, they’re expected here on September 24 each year.

But by the end of this week, millions of our second-most-favourite bird will be here, arriving in daily flocks of up to 60,000 birds an hour, having completed their incredible 16,000 kilometre journey from the waters off the Aleutian Islands near Alaska.

In the days and weeks ahead, huge flocks of these black bids will again be seen, rising as one around dusk, to wheel, swoop and bank in mass flight above the dunes on the southern side of the island.

They’ll already have renewed acquaintances with what for many of them is their lifelong partner and found their own nest, to which they return year after year.

The staff at Phillip Island Nature Parks have been on the look out for the return of the shearwater and will report on their arrival in the next few days.

“We’ve had reports of a few Shearwaters coming home last night,” said a spokesperson for Phillip Island Nature Parks on Tuesday.

“But we’re going out again tonight to get a better idea of numbers,” he said.

During breeding season, millions of Shearwaters converge on many small islands from NSW to Western Australia, with their stronghold in Bass Strait, mainly on Phillip Island.

In summer months, the Short-tailed Shearwater is the most common shearwater along the south and south-east coasts of Australia. Enormous flocks of birds head south to breeding grounds off these coasts as they return from wintering grounds in the North Pacific. Over 18 million birds make the trek.

At this time a number of birds are washed up on beaches and die as a result of exhaustion, sickness and bad weather. Most are birds hatched during the previous breeding season. Considering the incredible numbers of birds that make this annual migration, the number of fatalities is fairly small.

Shearwaters, or ‘Mutton Birds’, lay one egg in the last week of November in a sand dune burrow. The egg hatches in mid-January and the parents feed the chick before beginning their migration back to the northern hemisphere in mid-April.

They will fly up to 1500km per trip to forage for food, before returning to their burrows.

After their chicks are large enough to fend for themselves, the adults leave the breeding islands and migrate north-east in mid-April, flying on a broad front through the central Pacific Ocean, where immense numbers were seen by Captain Cook. They spend the southern winter at sea in the northern Pacific, off Japan, Siberia and Alaska.

The fat, fluffy chick is left behind until it grows its ‘adult’ feathers and begins the migration weeks after the adults leave.

While the chicks learn how to fly, they often end up on roads around Phillip Island, attracted to streetlights and the flat road surface. During this time, late April to mid-May, Phillip Island Nature Parks’ rangers and volunteers patrol roads and rescue wayward birds in danger of being hit by motorists.

Locals and visitors are made aware of this situation and take care while crossing the Island while the Shearwater road signs are out.

Some years ago, it is believed that climate change impacted the arrival date of birds in some areas, including at Port Fairy and authorities will be on the lookout to see if there are any impacts this year.