Few New Zealanders had heard of Reunion Island before a chunk of wing from missing flight MH370 washed up on the eastern shore in early 2015. But the island is well-known to ecologists as one of the worst examples of the impacts of humans on island ecosystems. More than half of the endemic birds are now extinct, and the island is over-run with introduced weeds and many species of introduced mammals, birds, reptiles and amphibians. It is a story too familiar to New Zealanders, and many of the same techniques are employed to control pests, down to the Philproof (NZ-made) rat bait stations I saw in La Roche Ecrite site within the Parc National.
Among the endemic fauna of the island are two poorly known petrel species – Barau’s petrel and Mascarene petrel. Barau’s petrel is now known to nest in at least two colonies on steep south-facing slopes above 2,200 metres in Cirque de Cilaos – but the first burrows were only discovered by chance by a climber in 1995. The second (and larger) colony was found the same way about 8 years later. They are relatively numerous (estimated at 15,000 to 20,000 pairs) but are likely to be in decline due to cat and rat predation, plus many birds (particularly fledglings on their first flight out to sea) are attracted to artificial lights, including street lights, where they are vulnerable to road-kill and also predation by domestic cats and dogs.
The Mascarene petrel is even more mysterious. No nests have yet been found, but eerie wailing calls thought to be made by this species have been heard at lower altitudes in a part of the island some distance from the Barau’s petrel colonies. Parc National staff have joined with university personnel, hunters and the local ornithological NGO (Société d’Études Ornithologiques de la Réunion, SEOR) to form the Life + Petrel project, seeking to discover the nesting sites of Mascarene petrels, and to protect both species.
My opportunity to visit one of the two Barau’s petrel colonies was largely due to the fortunate timing of my visit with the arrival on the island of Gerard Millischer, bringing a high-tech infra-red night-vision camera. Life + Petrel staff were keen to field-trial the gear on Barau’s petrels to see how far away flying petrels could be seen at night, before using the equipment at the suspected Mascarene petrel breeding site. The party of four (plus petrel-locating dog Life) was led by Patrick Pinet, who studied the bird for his PhD, and is now employed by Reunion Parc National.
The trip started with a drive up a long, winding road to Piton Maido – the highest point that you can drive to on the island, at 2190 m, and above the tree line. We then took the ute through forestry gates and continued for several more kilometres through lava fields and heath shrubland before the rough track petered out and we shouldered our packs. After a couple of hours we reached the high point of Grand Benare (2896 m) before descending 300 vertical metres down a steep unmarked route to the Vallie de la Deux Miche petrel study colony. En route and at the colony we found several cat-killed petrels, revealing one of the main threats to the survival of the colony.
The birds were incubating their single eggs, either in rocky crevices or (where enough soil had accumulated) in burrows dug under low shrub cover. We had arrived in the dense cloud and mist that forms over the peaks of Reunion Island every afternoon, and it was not until dawn that we could fully appreciate the spectacular setting of the colony – perched 1000 metres above the Cirque de Cilaos, and surrounded by sheer ramparts.
The infra-red camera proved to be highly successful at detecting flying petrels, and Life (the dog) demonstrated his developing skill at locating petrels by their smell. The Life + Petrel team hope that these two tools together can contribute to their efforts to locate and protect the breeding grounds of the Mascarene petrel, and to ensure the survival of one of the world’s least known seabirds.
Te Papa curator of vertebrates Dr Colin Miskelly visited Reunion Island in the Indian Ocean en route to the French subantarctic territories His visit to the Barau’s petrel colony was hosted by Reunion Parc National and the Life + Petrel project.
For further information (in French), see: