BirdLife: The Magazine September 2017 - Page 48

MARINE I t’s easy to appreciate how the breeding grounds of the Beck’s Petrel Pseudob- ulweria becki evaded human eyes for so long, given that their potential range spans the length of a vast, little-explored archipelago (see Petrel Patrol, June 2017). But what if we were searching for the breed- ing grounds of a different petrel species – one whose breeding range is confined to a single, remote island? That would be a piece of cake (or chum, if you prefer) in comparison, right? Well, not necessarily. We’re in Reunion, a small, French-owned volcanic island in the Indian Ocean, situated between Madagascar and Mau- ritius. It is here that you’ll find the Mascarene Petrel Pseudobulweria aterrima, another Criti- cally Endangered seabird, and indeed one of the rarest and most threatene d bird species in the world, with an estimated global population of just 100-200. Even so, with such a limited range, you wouldn’t necessarily expect the Mascarene Petrel to pull a disappearing act. Yet, like the Beck’s Petrel, this ocean-faring bird is so elusive that it once went unseen for many decades. The dramatic discovery of a grounded bird on the island in the 1970s was the first sighting for nearly a cen- tury, and it would be another 25 years before another specimen turned up. In between these long droughts, all we’ve had to go on are a few potential sightings at sea and its haunting noc- turnal calls, which have inspired many Creole tales and legends on the island. MASCARENE MASQUERADE IS OVER As the search for one breeding colony begins, another ends. After 15 years of research, a LIFE+ team has finally laid eyes on the burrows of the elusive, and highly threatened, Mascarene Petrel Alex Dale 48 BIRDLIFE • SEPTEMBER 2017 Which is a problem, because if there’s one thing we know for sure about one of the world’s most poorly understood birds, it’s that the Mascarene Petrel is in trouble. The species’ already slim numbers are suspected to be thinning further still as a result of two man-made factors. The first is light-induced mortality: a result of the birds getting disorientated and crashing due to urban lights. A public awareness campaign on the island organised by Reunion National Park – Nights Without Lights – has already done much to reduce the death toll. The other threat, however, will prove a lot harder to dim – namely, nest predation by introduced mammals such as cats and rats. Invasive spe- cies are a leading cause of island-endemic bird extinctions worldwide, but BirdLife’s recent suc- cesses in French Polynesia (see the June issue) are proof that their spread can be halted. However, the situation for every species is dif- ferent, so before we can develop an effective conservation strategy for the Mascarene Petrel, we need to better understand its ecology and breeding habits. No mean feat, when you’re talking about a rare, strictly nocturnal seabird SEPTEMBER 2017 • BIRDLIFE First picture of Mascarene Petrels in their breeding burrow. Photo LIFE+ PETRELS 0 Mascarene Petrel Pseudobulweria aterrima. Photo Martin Riethmuller/ LIFE+ PETRELS 2 THE MASCARENE PETREL IS ONE OF THE RAREST BIRD SPECIES IN THE WORLD, WITH AN ESTIMATED GLOBAL POPULATION OF JUST 100-200 Agents in the field. Photo LIFE+ PETRELS 1 suspected to nest in burrows high up on sharp, inaccessible cliff edges. However, this past November, following more than 15 years of research from an international team of ornithologists, an EU-funded LIFE+ Petrels project team managed to successfully discover an active Mascarene Petrel breeding colony for the first time ever. It’s a major break- through in our bid to better understand how to protect this species, and it was made possible thanks to a combination of old-school fieldwork and cutting-edge technology. “The Mascarene Petrel is only active at night, so to track its movements we needed the help of a new technological device – military infrared binoculars”, says Patrick Pinet, Scientific Man- ager of the LIFE+ Petrels project. “As far as we know it’s the first time this tool has been used for wildlife conservation.” The tool was acquired by the LIFE+ Petrels team thanks to a partnership with Mercantour National Park, an alpine wildlife refuge on the French-Ital- ian border. They were used, in conjunction with acoustic recordings and thousands of hours of observational fieldwork, to pinpoint cliff edges where the birds could frequently be seen landing – indicating a likely breeding colony. Once one such spot was identified, in a remote area of the south of the island, the next step was for a human expedition team to brave the steep, treacherous terrain to verify the colony. “We spent five hours walking in vertically sheer trop- ical woodland up to 700 m, then we rappelled down 15 m to reach the place we identified with infrared binoculars”, recalls Pinet. “The breeding colony is located in a crumbling, infirm volcanic cliff where you wouldn’t want to stay for long.” Because of the steep cliffs, the explorers could not rely on GPS alone to locate the suspected colony, and so were forced to remain in con- stant contact with the rest of the team down below, who parleyed instructions to them via walkie-talkies. Fortunately, the team got lucky and found the colony at the first time of ask- ing – perhaps guided by their nose, since the colony’s strong fishy smell could be detected from a distance of around 30 m. The discov- ery of these burrows means that the team can now move on to brainstorming practical ways to secure the species’ future. “The first, and most urgent step, is to protect the breeding colony from invasive predators”, says Pinet. “The second step is to take further meas- ures to ensure the species’ continued survival. We are currently considering two options: the first is to build a barrier around an established colony to keep predators out. The second is the construction of an artificial colony close to the sea, to avoid the issues created by urban light.” 49