Pétrel noir de Bourbon may sound like an exotic drink, but it is actually one of the rarest birds in the world. It is so rare, that it has taken a dedicated team of conservationists 15 years just to find their breeding grounds. In English the bird is known as the Mascarene petrel (Pseudobulweria aterrima) and is only known from the French island of La Reunion in the Western Indian Ocean (like Hawaii to the USA this island is part of France). Previously, the birds were only known from their haunting nocturnal calls, the local legends of the Creole people, rare sightings at sea and the occasional crash-landed bird in towns.
Since 2015 the LIFE+Petrels team has been intensively searching for the breeding site of the Mascarene petrel, listening to thousands of hours of audio recordings and exploring the most remote and steepest parts of the island. Back in 2008 I was fortunate enough to be working with Dr Patrick Pinet on Reunion Island when he undertook similar ground-breaking studies of the closely related Barau’s petrel, and as we located new colonies of this species, made tentative expeditions to try and locate the breeding ground for the Mascarene petrel. Dr Pinet is now the chief scientist in the LIFE+Petrels programme and in late 2016 they finally discovered the elusive breeding ground – by tracking the returning birds at night with infra-red equipment and abseiling down steep cliffs.
The discovery of the Mascarene petrel breeding ground after the species was presumed extinct has much in common with the rediscovery of the ‘extinct’ New Zealand storm petrel and its breeding site on Hauturu. Both demonstrate the ingenuity and dedication researchers must have to save species on the brink of extinction and understand their breeding biology. For both small seabirds the threats are also the same – predation by introduced mammalian predators, particularly cats and rats. Our modelling work on Reunion Island showed only eradication of both cats and rats, as occurred on Hauturu in New Zealand, will effectively save seabird species such as these. Predator eradication is not currently possible on Reunion Island so for now the LIFE+Petrels team will have to implement other conservation strategies such as predator-proof fencing and ongoing control.