Fregetta lineata

Bretagnolle, Vincent, Flood, Robert L., Gaba, Sabrina & Shirihai, Hadoram, 2022, Fregetta lineata (Peale, 1848) is a valid extant species endemic to New Caledonia, Bulletin of the British Ornithologists’ Club 142 (1), pp. 111-130 : 124-126

Breeding New Caledonian Storm Petrel Fregetta lineata

First confirmed breeding in New Caledonia.—On 26 September 2014, a juvenile F. lineata was caught by inhabitants of New Caledonia. Information is sparse, but it was found on the shore of mainland New Caledonia, in an inhabited area ( Fig. 1 ), and the juvenile probably was disoriented by street lights, as happens elsewhere with petrels, shearwaters and storm petrels ( Rodríguez et al. 2017). Photographs were taken that day at Port Bouraké, in front of Îlot Leprédour ( Fig. 10 ). In 2009, this islet became a nature reserve of the Province Sud. Eradication of European Rabbits Oryctolagus cuniculus from the islet is underway. The photographs were first sent to L. Renaudet (of the Société Calédonienne d’Ornithologie), who forwarded them to VB for identification. The bird had down on its head and nape, indicating a recent fledgling and confirming breeding on New Caledonia. No feather or blood samples were taken, and the bird was released. This is the only definite record of F. lineata on land and the only one indicative of breeding.

What is the breeding season in New Caledonia? —A fledgling in September points to winter breeding in the Southern Hemisphere. A six-month season is expected given the size of F. lineata . Thus, based on the fledgling, March–April is the likely egg-laying period. This corresponds with the majority of sightings in March and April off New Caledonia (Appendix 1). Further, numerous sightings as early as January off New Caledonia in 2020 suggest that egg laying may occur over an extended period, possibly January–April. In January 2020, off New Caledonia, birds were in rather fresh plumage, but tail and breast feathers were worn. The lack of primary moult and feather condition indicate that at least some were engaged in pre-breeding or breeding activities. (Primary moult of successful breeding storm petrels generally commences post-breeding.) Sightings off Australia perhaps correspond mainly to non-breeders. Indeed, birds there in March often had rather worn plumage and in April 2014 active wing moult was noted, which would not be expected in breeding adults. That said, some did not show obvious wear or moult.

Where exactly does it breed? —All islets in the southern lagoon of New Caledonia have been visited and carefully searched, with several nights spent on most of them ( Benoit & Bretagnolle 2002). No storm petrel was ever seen, no Fregetta whistling call was heard and, as far as we know, none of the many ornithologists who subsequently visited the islets has reported storm petrels. The only known storm petrel colony in New Caledonia was located in December 1999 in the interior of an islet off northern New Caledonia ( VB pers. obs.). Seven to nine burrows with entrances of c. 5–7 cm width were located in sand. No particular smell was detected and nothing was observed in the burrows. They were not disturbed as burrows in sand are easily and irreparably damaged. It was not possible to spend the night on the islet, but during several nights on neighbouring islets no storm petrel was seen or heard. Polynesian Storm Petrel Nesofregetta fuliginosa , a long-suspected breeder in New Caledonia, was believed to be the burrow owner. In May 2000, M. Pandolfi spent a night at the colony, heard whistling calls, but did not see or catch any storm petrels. Winter breeding supported the assumption that N. fuliginosa was involved. However, the following summer rats Rattus rattus were found on the islet. Although successfully eradicated in 2008, no one has located storm petrels on subsequent visits and no burrow has been found (J. Baudat & P. Villard pers. comm. 2008–18). The species of storm petrel involved remains unknown.

F. lineata may breed either inland or on islets in Bouloupari Lagoon (not visited). These islets are atypical and quite unlike southern lagoon islets. Some are rocky and most are surrounded by mangroves. The most suitable location would be Leprédour Islet where introduced mammals were recently eradicated. Any storm petrel population on the islet would likely have recovered somewhat, leading to at-sea sightings, as suggested for F. maoriana which breeds on Little Barrier Island where cats were recently eradicated. Alternatively, breeding may occur on mainland New Caledonia; a likely location is the Tontouta River valley where Pterodroma leucoptera breeds. High forested peaks along the coast, such as Dent de Saint Vincent, are also suitable search locations.

Apart from New Caledonia, the Marquesas Islands, where AMNH 194110 was collected, could hold a breeding population. The presence of subfossil bones attributed to Fregetta on Ua Huka and Tahuata ( Steadman 2006) might evidence the past presence of F. lineata . In addition, on 30 September 2013, one or two streaked storm petrels were seen south-west of Fatu Hiva, which provides hope that the streaked storm petrel survives in the Marquesas ( Flood & Wilson 2017). However, in September–October 2021, an 18-day seabird survey circumnavigating the islands recorded numerous storm petrels, but no streaked birds ( Flood et al. 2022). Perhaps seas around the Marquesas form part of the non-breeding range, given that the AMNH specimen and the recent sightings were in September, at the end of the likely breeding season in New Caledonia discussed above. Also, F. lineata could breed and survive on Samoa, where USNM 15713 was collected (especially if the bird was collected on land, see above). Mt. Fito would be a likely breeding locality, although again, the seas around Samoa could form part of the non-breeding range, as the specimen was collected in November.

Figures

Figure 1. Map showing all locations mentioned in the text, including the breeding location of New Zealand Storm Petrel F. maoriana; and the locations where specimens of New Caledonian Storm Petrel F. lineata were collected, at-sea sightings made, and the fledgling found. There has been discussion about the origin of the specimen NHMUK 1895.2.11.1 (Galbreath 2018).

Figure 10. New Caledonian Storm Petrel Fregetta lineata, Port Bouraké, New Caledonia, 26 September 2014; the first documented fledgling; note traces of down on head, stripes on belly diagnostic of F. lineata, narrow white fringes on dorsal feathers and upperwing (the latter most typical of F. grallaria) (photographer unknown, images supplied by L. Renaudet)