A Drone, an Algorithm and 17,108 Pairs: Counting the Gulf's Own Cormorant
The Socotra Cormorant nests on no other coast on earth. Its entire range is the Arabian Gulf and the Arabian Sea, split by the Strait of Hormuz, and the great majority of its breeding pairs sit on a handful of low, hot islands inside the Gulf. So a survey published in July 2026 about one Bahraini island is bigger news than its method suggests.
What a drone found on Rubud Al Sharqiyah
The study in Waterbirds, led by Sabir Bin Muzaffar with colleagues in Bahrain, the United Arab Emirates and the United States, counted nesting Socotra Cormorants on Rubud Al Sharqiyah in the Hawar Islands, Bahrain. Ground counts taken on 5 November 2023, at peak nesting, produced 17,108 ± 135 breeding pairs.
The same island was photographed from a drone on 20 November 2023, and the images were counted twice: by hand, which produced 12,762 breeding pairs, and by an empirical threshold algorithm, which produced 11,640. That roughly 9% gap is the point of the paper. It is acceptable for conservation work, the authors argue, given that the manual count took six hours and the algorithm took twenty minutes. A drone also keeps people off a colony at the worst possible moment: visits to nesting seabirds are a documented cause of lower productivity and lower survival.
The numbers underneath that number
Hawar is not one colony among many; it has been counted at up to 25,000 pairs, and the UAE's Siniya Island, off Umm Al Quwain, has been estimated at 28,000 to 41,000 pairs. The species reaches about 110,000 breeding pairs worldwide, 86% of them inside the Arabian Gulf and only about 10,000 pairs on the Arabian Sea side, along the coast of Oman. About twenty Gulf colonies are currently in use — nine of them in the UAE — with others abandoned as human activity arrived.
The species is also still finding new islands. A colony has established itself on the World Islands, the man-made archipelago off Dubai, and birds from Siniya Island in Umm Al Quwain move southwest after breeding towards islands in Abu Dhabi, with some dispersing as far as the Musandam peninsula. On rare occasions Siniya birds have crossed Qatar into Kuwaiti waters and mixed with birds that normally breed at Hawar.
The trajectory is what worries conservationists. BirdLife International's estimates for the species fell from 450,000–750,000 birds in 2000 to about 220,000 in 2018, and the Socotra Cormorant is listed as Vulnerable on the IUCN Red List. The stated reasons are a small range, habitat loss to coastal development, disturbance at breeding sites, oil pollution and predation.
Two populations, one strait
A second study, posted as a preprint in April 2026, put the first genetic numbers behind that picture. It sampled 279 cormorants from four Gulf colonies and one on Hasikiyah Island in the Arabian Sea, using two markers: mitochondrial COI, which is inherited only from the mother, and a nuclear region called β-fibrinogen intron 7.
The COI results describe the Gulf birds as a single population with extensive exchange between colonies — except between the two most distant ones, Hawar in Bahrain and Siniya in the UAE — and as clearly separate from Hasikiyah beyond the Strait of Hormuz. The Gulf population showed significantly lower nucleotide and haplotype diversity than the Arabian Sea colony. The nuclear marker, by contrast, detected no structure at all. The disagreement between the two is not a contradiction but a lesson in how the species moves, It also matches the oceanography: a frontal zone running north through the Strait of Hormuz separates water masses, plankton and the animals that feed on them between the Gulf and the Arabian Sea, and no individual cormorant has ever been recorded moving between the two regions. This is the first genetic characterisation of the species ever published.
The concern is straightforward: a population that is isolated and genetically narrow has less room to adapt, and the study says so plainly about the long-term viability of the Gulf birds.
Why an annual count is the whole game
Colonial seabirds are mobile and capable of abandoning a site. Cormorant numbers at a given island can swing with fish, disturbance or a single bad season, which is why the authors call for annual monitoring of every colony at peak nesting and for survival rates to be tracked, not just nest counts. A method that costs twenty minutes instead of six hours is what makes that realistic across a region where the colonies belong to several different countries.
Listening on a Gulf shore
The Socotra Cormorant is the one voice missing here: its page on this site is live, but xeno-canto holds no recording of it under a licence we can host, so it carries no player yet. What you can hear are the shorebirds and gulls that work the same mudflats and island edges — the species you will meet on the way to a cormorant colony.