nchored for the night in a secluded bay on the island of La Gomera, we are winding down for an evening of star gazing when a raucous, disembodied voice squawks out from the darkness. One call becomes two, then a crescendo as the air fills with a rowdy gathering of feathered seafarers about to make landfall for the night. Some are growly, others higher pitched and cackling, building in volume then fading away. Occasionally I catch sight of a ghostly outline and hear the whooshing whisper of strong wings as one passes close overhead – Cory’s shearwaters returning from a day at sea in the hundreds.

Having dropped anchor in daylight we were unaware we had settled beside a breeding colony in peak season. What a wonder! In the coming months this would become our evening soundtrack wherever we settled for the night. We’d seen them at sea in the daytime, skimming the ocean surface or bobbing in rafts snoozing with heads tucked beneath a wing. Before first light they head to sea, dividing their time between resting, preening, socialising and plying the clear waters for bait balls and squid to hunt. Adept swimmers both at the surface and underwater, they are able to dive to 15m depth or more in search of prey using both wings and feet to power the pursuit. On several occasions we’d watched them follow pods of foraging bottlenose dolphins, picking off fish driven to the surface by the underwater chase. Apart from the occasional squabble over scavenged food, during the day they are mostly quiet, saving their peculiar vocalisations for night time revelry.

Their return to the cliffs at night provides cover from predatory gulls that would otherwise ambush and eat them. They arrive with bellies full of fish to feed their young or take overegg incubation duties from their partners secreted in a dusty cave or nest hole in the cliffs.

It’s strange to think that a bird highly adapted to a life spent roaming the open ocean, begins life entombed in the earth, born among volcanic rock and ash. Drawn to the land by carnal urges, their instinct to breed turns their gaze from open ocean to the parched cliffs of the Macaronesian islands that are a strong-hold for these birds. The entire south, east and west coasts of La Gomera are alive with huge colonies by night. Protected by European law under the Birds Directive, the cliffs are part of the La Gomera-Teno marine area that encompasses the whole coast of La Gomera and offshore across the water to the far west coast of Tenerife. This area includes nest sites and foraging habitat for not only Cory’s shearwaters but other seabird species as well. The law forbids hunting during migration and at nesting areas, protecting them from poaching that historically caused major declines, but it misses the other more impactful threats. Introduced species such as black rats and feral cats can wreak havoc at colonies, picking off juveniles and eggs, whilst at sea accidental death in hook-based fishing gear is hugely damaging to populations.

From the moment of hatching the chicks spend around 90 days in the ground, building bones and feathers for a life at sea from a diet of regurgitated fish paste. Once the chicks have grown fat and feathered in their nest holes (50 days), the parents take their leave, abandoning them to fledge alone. A few weeks later the chicks emerge, hungry and with an epic journey ahead of them, not to mention having to learn how to catch fish. Getting airborne is their first challenge, requiring a daring launch from the cliff. They then embark on a long-distance, figure-eight migration that curves and loops to the four corners of the Atlantic ocean; a maiden voyage of thousands of miles. Guided by an innate navigation system, they are endowed with avian super powers that steer them along routes they’ve never travelled before, the same sea paths taken by their kin. Highly adapted to this pelagic existence, their long, stiff wings allow them to glide and soar great distances with little effort. As members of the Procellariiformes or tubenoses alongside petrels and albatrosses, they are able to desalinate seawater, extracting fresh water from the brine then sneezing out the salt. By side-stepping the need to drink freshwater they are free to live a life at sea, soaring, swimming and fishing.

Our premier shearwater matinee was in early April. By October the cliffs were quiet at nightfall, the parents having left for the high seas. Yet I knew hidden in the cliffs were hundreds of chicks on the cusp of venturing out to sea for the first time.