A Sable Shearwater chick leaves Lord Howe Island only once as a fledgling, having never flown further than its burrow entrance, never fed itself, and never seen the open ocean. Researchers at Adrift Lab attached solar-powered GPS tags to thirty of these young birds as they prepared to leave in 2022 and 2024, tracking where their first-ever journey took them. The results, published in the journal Animal Biotelemetry titled ‘Post-fledging migration of Sable Shearwaters (Ardenna carneipes) identifies the Solomon Sea as a potential conservation priority,’ pointed to a place few people had ever thought to look, the Solomon Sea. Here’s what the tracking revealed, and where the project ran into trouble.
Tracking 30 fledgling shearwaters on their first flight from Lord Howe Island
Within two weeks of leaving Lord Howe Island, the tagged Sable Shearwaters had travelled, on average, nearly 1,000 kilometres, with one bird covering almost 1,200 kilometres in a single day. Then, in week three, the same pattern emerged across both tracking years, every bird arrived in the Solomon Sea and stayed there, moving only short distances east to west, sometimes for weeks. While adult Sable Shearwaters were already known to use nearby waters, this marked the first evidence that fledglings converge on the Solomon Sea so quickly and so reliably, suggesting the region plays an important role for young birds during one of the most dangerous periods of their lives.
Researchers at Adrift Lab attached solar-powered GPS tags to the birds (Image: Canva)
Why the Solomon Sea is such an unexpected discovery
The Solomon Sea is oceanographically unusual; strong currents move through a maze of islands and straits, drawing nutrients up from the deep and enriching the surface waters. It is a global hotspot for nitrogen fixation, warm year-round enough to support the productivity underpinning entire food webs, with coral, reef fish and seagrass diversity ranking among the highest in the world. Despite this, the Solomon Sea is barely represented in seabird research and isn’t even included in the West Pacific Ocean Flyway, likely because few surveys have passed through at the right time of year, leaving juveniles largely missing from conservation maps of the region.
When the tracking technology let researchers down
Tracking newly fledged seabirds proved difficult. Nearly a third of the tags deployed in 2022 stopped transmitting within the first two weeks, some after only a handful of fixes, and three more were defective before the birds even left the ground. A separate fault also meant the accelerometer data researchers rely on to detect mortality never came through properly, leaving them unable to say for many silent tags whether the logger had failed or the bird had died. For the 2024 deployment, the team switched to loggers with seven times the battery capacity, hoping to keep birds transmitting for longer.
What the failed tags and missing data might really be telling us
Even with an imperfect dataset, the birds that did transmit told a consistent, coherent story across two entirely separate years, a repetition the researchers see as a strong signal in itself. Three quarters of the shearwaters in the study had ingested plastic, some carrying close to 20 grams of it, and Sable Shearwater survival to breeding age is already markedly lower than in closely related species. Set alongside nearly a third of tags going silent within days of fledging, researchers say the missing tracks may reflect early mortality this population is known to experience, rather than simple equipment noise, a pattern they plan to keep watching for.