A buzzard form known for over 100 years has been declared a 'good' species in a recent paper.
The Socotran Archipelago consists of four islands in the Indian Ocean, just off both the Horn of Africa and the southernmost tip of the Arabian peninsula. Though not as well known as the Canary Islands and the Galapagos, it is very much an island biodiversity hot-spot, holding many plants and animals found nowhere else on earth.
Notable among these are several endemic species and subspecies of birds, including an endemic genus of warbler. The buzzards of Socotra are also distinctive, and have now been split as a full species.
Discovered more than 111 years ago, the resident Buteo was never formally described and named. The taxonomy of the genus is notoriously complex, partly due to a relatively recent radiation across the Old World from the Americas, but Socotra Buzzard has been informally considered as a subspecies of Common Buzzard for most of the last century, sometimes as part of the eastern form 'Steppe Buzzard'.
Much more recent work on genetic markers has found that Socotra Buzzard clusters with North African Long-legged and Common Buzzard, and all three form a single superspecies with little genetic differentiation, along with an African form, Mountain Buzzard. Morphologically, the Socotran form shares most of its characters with Long-legged and Mountain Buzzards.
Using the limited museum specimens and field observations, the authors itemised diagnostic plumage and bare part measurement differences for all ages. They consider that the differentiation of Socotra Buzzard is equivalent to that between most of the other accepted Old World Buteo species, and have therefore formally declared it a new species.
Conservationists have now accepted the new species, and it has now been classified as Vulnerable by BirdLife International.
Porter, R F and Kirwan, G M. 2010. Studies of Socotran birds VI. The tazonomic status of the Socotra Buzzard. Bulletin of the British Ornithologists' Club 130: 116-131.