Justification of Red List Category
This species may have undergone a rapid population decline owing to illegal shooting in the 1990s, but has apparently recovered. However, it has a very small range when breeding (probably at fewer than five locations) and a small population, both of which are thought to be declining. It is therefore classified as Endangered.
Most breeding colonies of Barau's Petrel are completely out of reach and have never been assessed properly until recently. Thus, most previous population estimates and trends should be taken with caution. Recently, a combination of methods including annual census of fledglings attracted to lights from 1996 to 2016 (SEOR unpublished), wide scale radar survey, capture and recapture analysis at breeding colonies, study of burrow occupancy, habitat modelling (and population genetics (Danckwerts et al. 2016) have been conducted to assess the size of the population. Such an effort has provided a preliminary estimate of 15,000 to 20,000 breeding pairs, a larger number of mature individuals than previously reported. Nevertheless, previous estimates were based only on a partial knowledge of the species.
The species was suspected to be undergoing a long-term decline in line with increased juvenile mortality caused by disorientation resulting from light pollution. Both adults and chicks are also predated by introduced mammals (cats and rats) at breeding colonies.
Pterodroma baraui nests on the Massifs of Piton des Neiges and Grand Bénare, La Réunion (to France) (one nest has been discovered on Rodriguez; Van den Berg et al. 1991). Tracking research has shown that the at-sea distribution when breeding includes a wide area from Reunion to 1,000 km south of Madagascar and up to the coasts of South Africa (Pinet et al. 2012). After breeding, the species migrates eastward to a wide area located on both sides of the 90 East ridge (Pinet et al. 2011b). At sea observations in the northern Indian Ocean suggest that some birds may disperse widely throughout the tropical Indian Ocean.
It nests on cliff-ledges in volcanic ash soils beneath sparse, heathy vegetation such as Philippia montana associated with upland elfin forest (Probst et al. 2000). It is a summer breeder, with most birds arriving at the colony in September; the pre-laying exodus occurs in October and birds lay synchronously in November each year. Chick-rearing starts in late December to early January and fledglings leave their colony throughout April. Breeding adults forage over a wide area between Réunion, the south of Madagascar and South Africa (Pinet et al. 2012). Pre-breeding and incubating birds perform very long foraging trips up to the continental plateau of South Africa and the Walter Shoal area, 1000 km south of Madagascar. When rearing their chicks, birds adopt a dual foraging strategy with a clear alternation of short (2-3 days) trips around Réunion Island and long trips (10-14 days) trips to the south of Madagascar. During the non-breeding season, it forages in regions characterized by warm sea surface temperatures and low productivity, consistent with strong and reliable easterly winds, between the western South Equatorial Current and the eastern Equatorial Counter Current (Pinet et al. 2011a). Birds leave the colony in late March, reaching wintering areas in mid-April, returning to the colony 5th-15th September (Pinet et al. 2011b). Both sexes, as well as breeders and non-breeders, show similar migration schedules, with males returning to the colony slightly earlier, and mean return dates coinciding with the full moon phase, suggesting that birds use this cue to synchronize their activity (Pinet et al. 2011b). The mean distance travelled per day en route to wintering areas is 110-600 km; once there, travel distances drop significantly (Pinet et al. 2011b). There is considerable consistency in wintering areas year on year (Pinet et al. 2011b). The species feeds at the surface, taking mostly squid and fish, foraging alone or in small flocks, often associating with Sooty Terns Sterna fuscata and Tropical Shearwaters Puffinus bailloni. Diet study and stable isotope ratios suggest that young and adults consume different prey (Kojadinovic et al. 2009, Danckwert et al. 2016). Its main prey are fish and squids.
Invasive mammals represent the largest threat to Barau’s Petrel. Cat predation is the most significant threat to the species with modelling indicating that the rate of predation is likely to be causing rapid population declines (Russell et al. 2009). Introduced rats are also a significant threat to the species, taking eggs and chicks and have been recorded at all visited breeding colonies (Pinet et al. 2009, M. LeCorre in litt. 2016). Goats and dogs are also present, however, these are thought to cause negligible declines.
Light pollution represents a significant threat due to the disorientation of juvenile birds and has been the target of Intensive conservation action. Light pollution is estimated to potentially lead to between 5 and 20% mortality dependent on weather and moon phase (M. LeCorre in litt. 2016); over 13,000 fledglings have been rescued since 1996 (M. LeCorre in litt. 2016). Widespread light pollution such as street lamps and sport installations are responsible for the vast majority of petrel light-induced mortality on Réunion (Le Corre et al. 2002).
Climate change may also affect the species in the future as a recent study based on a robust tracking dataset and habitat suitability modelling has shown that the wintering habitat may shift southward and may be reduced in size during the 21st century (Legrand et al. 2016).Hunting is likely to have had a small effect on this species, causing rapid declines in a small portion of the population, but this threat is considered unlikely to return.
Conservation Actions Underway
Since the discovery (in 1996) of the massive loss of fledglings induced by light pollution, an island scale rescue campaign has been conducted annually and has lead to the rescue of >12,000 fledglings. Recent mark-recapture operations conducted at breeding colonies have shown that some of these birds are now recruiting as breeding adults, which demonstrates that rescue campaigns have a strong positive impact at the population level. A modelling study also shows that without the rescue campaign, the population would have declined at a rate of at least 1.1% per year (Le Corre et al. in prep.).
Measures to reduce light pollution, especially during the fledging period (April), have been proposed (Le Corre et al. 2002). Since 2004, the community of Cilaos, close to the species's colonies, has taken part in efforts to reduce lighting, and there has been a corresponding decrease in the numbers of grounded birds. More recently the National Park of Réunion Island has implemented a joint initiative to reduce light pollution at the scale of the whole island. All known breeding colonies are fully protected since 2007 within the core area of the National Park. Finally, a LIFE+ project is currently underway (2015-2020) to develop various conservation actions, including the control of feral cats at and near most breeding colonies.
Conservation Actions Proposed
Carry out surveys to obtain an up-to-date population estimate. Conduct regular surveys to monitor population trends. Control predators, particularly cats at breeding colonies (V. Bretagnolle in litt. 1999, 2007). Cat control at breeding colonies is required year-round, particularly during the non-breeding season when efforts are likely to have the most effect due to the reduction of other available prey (Pinet et al. 2009). Instigate a comprehensive education program to demonstrate the impact of feral cats to the local population (Pinet et al. 2009). Continue rescue programme of young birds attracted by lights (Le Corre et al. 2002). Investigate light-reduction programmes either through light-shielding or light-restriction during April and May (M. Le Corre in litt. 1999, Le Corre et al. 2002), and consider adjusting its direction, intensity and colour, and the use of temporary black-outs (Salamolard et al. 2007).
38 cm. Medium-sized, grey-and-white gadfly petrel. White forehead, black cap merging to greyish-brown back and upperwing. Paler wing-tips give scaled appearance. Slightly darker tail. Moderately defined M mark across wings. White chin, throat and rest of underparts, except for some grey mottling on sides of breast and flanks. White underwing with dark trailing edge, dark tip, narrow black edge to leading edge distal to carpal joint. Black thickens at joint. Then clear black bar extending from joint towards centre of wing. Similar spp. Capped appearance, white underparts, and distinctive underwing separate this from any other Indian Ocean Pterodroma.
Text account compilers
Shutes, S., Stattersfield, A., Stuart, A., Taylor, J., Temple, H., Benstead, P., Ekstrom, J., Anderson, O., Fjagesund, T., Hermes, C., Martin, R., Calvert, R., Moreno, R.
Couzi, F.X., Le Corre, M., Attié, C., Gee, B., Bretagnolle, V., Pinet, P., Lequette, B., Salamolard, M.
BirdLife International (2019) Species factsheet: Pterodroma baraui. Downloaded from http://www.birdlife.org on 09/12/2019. Recommended citation for factsheets for more than one species: BirdLife International (2019) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 09/12/2019.