Almost ten per cent of yelkouan shearwaters, a protected Mediterranean seabird, breed on the Maltese coast, a new study has found.

Ornithologists Marie Claire Gatt and Benjamin Metzger tracked and followed the movements of a number of young seabirds, also known as a garnija or Puffinus yelkouan, thanks to technology which gave them data on the young birds’ movements in real-time.

Ornithologist Marie Claire Gatt fitting one of the birds with a tracking device.

Despite spending most of their lives at sea, hundreds of shearwaters live nestled in Malta’s coastal cliffs between November and July, as breeding pairs attempt to hatch and raise a single chick. Outside of the breeding season, the birds can remain at sea without approaching land for months on end.

In collaboration with the Mediterranean Science Commission’s International Seabirds Project, the study sought to find out more about juvenile yelkouan shearwaters, as following maturity little is known about this stage of their lives.

With the help of the Birdlife Malta Seabird team, Gatt and Metzger fitted five adult and 14 fledgling yelkouan shearwaters with GPS-GSM transmitters that allowed them to track the birds’ migration out of Maltese waters with “unprecedented spatial and temporal accuracy”.

As the young birds spend such a long time away from the coast, their habits had been something of a mystery to scientists before the facility of lightweight technology that allowed for remote tracking, the study said. The devices were unlikely to be retrieved from the young birds as they don’t return to the colony in their first years of life and have a low chance of survival.

The study confirmed that once chicks are fully grown, both parents abandon the colony, and the juvenile bird is likely to take off by itself into the night around a week later.

Results showed adults foraged in the central Mediterranean before migrating to the Black Sea or north to the Adriatic.

Meanwhile, when the fledglings, who previously have only known the rock crevice that they hatched in, finally take off they tend to bear north, with most flying straight to the Aegean.

“Since their parents leave the breeding colony earlier, fledglings cannot follow them to distant destinations. Instead, they rely on navigational cues in their genetics for their first voyages,” the study shows.

“The first year of life is the most dangerous for these long-lived birds, as they have yet to master the necessary skills for a life at sea.

“Of the 14 young birds that left the colony, one died while transmitting data and washed ashore on the Egyptian coast, where local colleagues were able to find its remains.”

Speaking to Times of Malta, Gatt said that as marine predators yelkouan shearwaters were often indicators of the overall health of the ocean.

“In many ways, they are important to study because they are sentinels of the sea and if something is wrong in the water, it will be reflected in their patterns of behaviour,” she said.

“As dry land is practically alien to them, they are particularly vulnerable. Every breeding pair only raises one chick per season and if something goes wrong, that’s it.”

Because fledglings scarcely make land in their first years of life, the study was critically important in learning new things about their first week out at sea, she said.

Because birds have no borders, learning more about their habits helps build a stronger basis when it comes to protecting them, especially legislatively.

“In terms of the EU Birds Directive, the yelkouan shearwaters are already highly protected, so much so that they are even the basis of the awarding of some Natura 2000 sites in Malta,” Gatt said.

“This is why when there is a development that could potentially impact their nesting sites an environmental impact assessment is automatically triggered.”

“However, just because legal protections exist on paper, it does not mean that they are always effective,” she added.

“A classic case of this is in Sannat, for example, where authorities decided that just because there are already buildings there then large-scale developments would not have an impact.

“An upcoming challenge is also likely to be posed by the bungalows proposed in Comino, some of which are only 40 metres away from a yelkouan shearwater colony.”

The birds are also highly sensitive to light, a sensitivity that can prove fatal to inexperienced birds who spend most of their lives out of contact with the land.

“They are very similar to baby turtles because they are so sensitive to light pollution.

“It can disorientate them and before you know it they crash land into a city and if no one intervenes they will die there,” Gatt said.

“Light pollution spilling out onto the water is also a death trap, because land is so alien to them they will veer off course and enter a terrain on which they do not know how to survive.”

Gatt stressed the importance of protecting shearwaters and facilitating conservation efforts that allow them to thrive.

“We have to do our utmost to keep these colonies safe and allow these young birds to leave and come back to repopulate their colonies,” she said.

“They really are a treasure, and we should be proud to have them on our shores.”