Mascarene Petrel
Pseudobulweria aterrima

Procellariiformes Order – Procellariidae Family

The Mascarene Petrel is one of the rarest and least known birds in the world. It is endemic to Reunion Island. Following the discovery of fossil bones, it is known that it was formerly present and endemic to Rodrigues Island, but there are no recent records. It is vagrant to Mauritius where nesting is a possibility.   
The behaviour of the Mascarene Petrel is very poorly known. It probably feeds on cephalopods and small fish like other Procellariidae.
The breeding habits are unknown, although some recent observations show this species near the nest, a burrow, in inaccessible cliffs where a small colony was established. Protection measures are in progress to ensure this species.

The Mascarene Petrel has a very small breeding population threatened by cats and rats, but also by urban lights affecting the young birds. The species is still declining and currently classified as Critically Endangered.

Length: 35-36 cm
Wingspan: 88 cm
Weight: 174-270 g

The Mascarene Petrel has blackish-brown plumage overall, but slightly paler on chin and upper throat. On the underwing, the flight-feathers have silvery tinge at bases, but the coverts are very dark.
The bulky bill is black. The eyes are dark brown. The legs are pinkish but the black webbed feet have pale flesh base of inner toes.
Male and female are similar.
The juvenile resembles adults but it has narrower bill.

The Mascarene Petrel is very difficult to identify at sea, with up to nine entirely dark petrels (with dark morphs) and shearwaters sharing the same waters.

The Mascarene Petrel is endemic to Reunion Island, and formerly to Rodrigues Island.

The Mascarene Petrel is marine and pelagic like most Procellariidae. From a recent observation, the breeding colonies are established on inland cliffs or ravines, within the mountain forest of the island, from 500 metres to 1,150 metres of elevation (one record at 1,700 metres).

The Mascarene Petrel gives high-pitched, drawn-out scream “crrreeeeeee-awwwwwww” of 2-4 seconds, usually repeated at 5-10 seconds intervals and dropping at the end. We can also hear a more whinnying “creeeeewewewewe…”
Two other calls by non-breeding adults include a short shriek and a short whinny, similar to incomplete versions of the two main calls.

The Mascarene Petrel feeds probably like other petrels, taking mainly cephalopods and small fish.
This species has been observed on sea surface, scavenging on floating debris.
Petrels usually feed by surface-seizing while sitting on the water. The bird lands on water and swims towards the food with the wing partially open. It only takes surface food items.

The breeding behaviour is unknown. It nests in burrow on high cliffs and sometimes in small, loose colonies.

The Mascarene Petrel is usually present at sea around Reunion Island, with records at more than 1,300 km from the island between November and March. There are probably also some movements related to food resources.

The Mascarene Petrel has typical flight of genus Pseudobulweria, an effortless flight on long wings sometimes slightly bowed and at other times fully stretched and extended.
During the glides, the wings are held stiff and straight. In moderate winds, the flight is deliberate with some few shallow wingbeats and regular zigzag advance along a straight course. Soaring action is interspersed with some quicker, shallower wingbeats.
Seen from the front or from behind, the wings are held slightly below body level and form a shallow arc.
These observations indicate that the Mascarene Petrel flies generally low over the sea surface, and disappears between the waves before to reappear suddenly.

The breeding season takes place approximately between November and March, with the incubation in October-December. Fledglings have been seen between early March and early April.
In December 2012, a Mascarene Petrel was seen at sea with a large egg protruding from the belly, indicating the return of a female from a pre-laying exodus.

From a recent observation, we know that the Mascarene Petrel nests in burrows in the ground, in steep, inaccessible cliffs. It nests in small, loosely spaced colonies with just 4-10 pairs.
Birds calling from the ground at night were probably males at burrow entrance, trying to attract females.

The incubation is believed to last 48-50 days, and the chick-rearing 73-82 days. Fledglings have been recovered over a two- month’s period, and this species probably has unsynchronized laying and extended laying period, like most tropical petrels.  

The Mascarene Petrel has very small breeding population and is a restricted range species.
It is threatened by cats and rats, but urban lights affect the inexperienced juveniles. Cats kill both adults and young, whereas rats are the main predator of the nests.
As this species feeds at sea-surface, it is also vulnerable to interactions with fisheries. In the past, it was killed for human consumption.

The population was estimated at 100/200 mature individuals in 1999. A more recent estimate in 2011 gives just a few dozen pairs, and another more recent sighting at sea, S of Reunion Island, suggests that the breeding population size is 100 pairs (2014). This population is still declining.
The Mascarene Petrel is currently classified as Critically Endangered.

Fr: Pétrel de Bourbon
Ang: Mascarene Petrel
All: Maskarenensturmvogel
Esp: Petrel de Reunión
Ita: Petrello delle Mascarene
Nd: Maskarenenstormvogel
Sd: réunionpetrell

Text by Nicole Bouglouan


HANDBOOK OF THE BIRDS OF THE WORLD vol 1 by Josep del Hoyo-Andrew Elliot-Jordi Sargatal - Lynx Edicions - ISBN: 8487334105

Birds of Madagascar and the Indian Ocean Islands Par Roger Safford, Adrian Skerrett, Frank Hawkins – ISBN: 1472924118, 9781472924117- Editeur: Bloomsbury Publishing, 2015

The Birds of Africa: Volume VIII: The Malagasy Region: Madagascar, Seychelles, Comoros, Mascarenes - Par Roger Safford, Frank Hawkins – ISBN: 1408190494, 9781408190494- Editeur: A&C Black, 2013

Avibase (Denis Lepage)

Birdlife International

HBW Alive

Life+ Pétrels

SEOR – Société d’Etudes Ornithologiques de La Réunion

The Critically Endangered Mascarene Petrel Pseudobulweria aterrima: identification and behaviour at sea,historical discovery of breeding sites, and breeding ecology on Réunion, Indian Ocean
By Hadoram Shirihai, Tony Pym, María San Román & Vincent Bretagnolle

Rescue of the Mascarene Petrel, a Critically Endangered Seabird of Réunion Island, Indian Ocean

Futura – Sciences

Rare Bird Alert - Nesting colony of Mascarene Petrel seen for first time

Wikipedia, the free encyclopaedia


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