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Seabird life-history traits such as long generation time, low annual fecundity and delayed sexual maturation make them more prone to population loss and consequently to extinction; petrels are indeed amongst the most threatened birds. Based on coalescence and multiloci inference this study examines the extent of genetic differentiation of a vulnerable New Caledonia (caledonica) and Australia (leucoptera) subspecies of Pterodroma leucoptera (Gould’s Petrel), and whether the genetic relationship between them results from the influence of past events like variation in sea level, or is dominated by contemporary gene flow. Sequences of two mitochondrial genes and five nuclear introns were obtained from 86 individuals from both populations. Haplotype networks were used to infer relationships between the haplotypes of both populations. The demographic history of the P. leucoptera complex was studied using neutrality tests and Extended Bayesian Skyline Plots. A weak population differentiation was revealed. The Extended Bayesian Skyline plot suggested a population expansion approximately 80,000 years before present (bp) for caledonica and 30,000 years bp for leucoptera. The split was dated to 30,000 years bp by means of multilocus inference through *BEAST. Despite genetic similarity of the two taxa, we advocate to consider them as independent units for conservation management, given their strong ecological distinctiveness (foraging distribution, winter distribution, breeding phenology and breeding distribution).

International audience; Niche divergence is expected for species that compete for shared resources, including migrants that occupy similar regions during the non-breeding season. Studies of temperate seabirds indicate that both spatial and behavioural segregation can be important mechanisms for reducing competition, but there have been few investigations of resource partitioning by closely related taxa in low productivity, tropical environments. We investigated niche partitioning in 3 gadfly petrel taxa, Pterodroma leucoptera leucoptera (n = 22), P. leucoptera caledonica (n = 7) and P. pycrofti (n = 12), during their non-breeding season in the eastern tropical Pacific Ocean by combining tracking data from geolocator-immersion loggers with remotely sensed environmental data in species distribution models (SDMs), and by comparing feather stable isotope ratios. The 3 taxa showed spatial partitioning: two foraged in the North Equatorial Counter Current and one in the South Equatorial Current. This reflected differences in their realised habitat niches, with significant taxon-specific responses to thermocline depth, sea surface temperature and bathymetry. There were also differences among taxa in activity patterns, and all birds spent a much larger proportion of time in flight at night than during the day, suggesting predominance of nocturnal foraging behaviour. Comparison of stable isotope ratios in feathers suggests that P. l. leucoptera and P. pycrofti mainly consume vertically migrating mesopelagic fishes, whereas the diet of P. l. caledonica also includes some lower trophic levels including crustaceans and squid. Unique insights can be gained from studies of the foraging ecology of tropical pelagic seabirds, in comparison with temperate and polar waters, and are urgently required for understanding and protecting tropical avifauna in key marine habitats.

Australia's most widespread palm, the Cabbage Tree Palm Livistona australis (R. Br.) Mart. has only a few offshore populations, but one of considerable significance is on Cabbage Tree Island on the mid-north coast of New South Wales. This island is also the principal breeding site of a threatened endemic seabird, the Gould's Petrel Pterodroma leucoptera leucoptera. This paper outlines some of the ecological interactions between this iconic palm and this enigmatic seabird. P. leucoptera nests in rock cavities, under fallen palm leaves, or in hollow fallen palm trunks. It takes to the air by climbing to the top of palms and is sometimes killed by colliding with them. The eradication of the European Rabbit Oryctolagus cuniculus from Cabbage Tree Island in 1997 was undertaken to remove one of the threatening processes endangering P. leucoptera. This action has in turn released the population of L. australis from 91 years of unsustainable grazing pressure, helping to restore the long-term integrity of this, an...

Many petrels show no obvious sex-linked dimorphism in plumage or size and consequently many researchers fail to sex the living individuals they study. Several methods of sex discrimination that do not rely on plumage- or obvious size-dimorphism can be used to sex live petrels. The effectiveness of three such techniques was evaluated: body condition at the time of laying, cloacal inspection, and discriminant function analysis (DFA) of external morphometrics. Gould’s Petrel (Pterodroma leucoptera leucoptera) was used as the subject species. Sexing of breeding adults on the basis of body condition at laying proved to be highly accurate (100% of birds sexed correctly) but required detailed knowledge of the breeding biology. Following training, cloacal inspection proved to be an accurate (96%) method of determining the sex of breeding adults, but not of chicks. Unlike molecular sexing, the latter two methods of sex discrimination provide immediate knowledge of the sex of individuals in the field. DFA of external morphometrics predicted the sex of adults with an accuracy of 73% and the sex of near-fledged chicks with an accuracy of 66%. However, the probability of correct assignment of sex was low in most cases and, therefore, this is the least useful of the three techniques assessed here.

Gould’s petrel (Pterodroma leucoptera leucoptera) was restricted, essentially, to a single breeding locality – Cabbage Tree Island, Australia. As a safeguard against extinction, an additional breeding colony was established on nearby Boondelbah Island, where artificial nesting habitat was created by installing 100 plastic nest boxes. Over two years, a total of 200 nestling Gould’s petrels were translocated from Cabbage Tree Island to these boxes. Colonies on both islands were then monitored for a further four years. Selection of nestlings for transfer was based on prior knowledge of growth, plumage development and emergence from the burrow, and aimed to select only birds that were 11–28 days from fledging (DBF) in 1999 and 11–22 DBF in 2000. Of the first 100 nestlings translocated to Boondelbah Island (in March 1999), 95 fledged successfully 8–27 days after transfer (mean = 17.3 days). Of the second 100 nestlings translocated (in March 2000) all successfully fledged 9–22 days after transfer (mean = 15.1 days). The removal of young had no discernible effect on the subsequent breeding productivity of the donor pairs. In all, 41 Gould’s petrels have been recorded at the new colony on Boondelbah Island, where at least 27 nest boxes have been visited. Ten translocated fledglings (nine male, one female) have returned to the translocation site, taking up nest boxes that were, on average, 5.5 m from the box from which they fledged. An additional 27 non-translocated birds, of unknown origin, have also nested in nest boxes on Boondelbah, along with four birds previously known from Cabbage Tree Island. Two nestlings transferred to Boondelbah Island have returned to Cabbage Tree Island. Within five years of the first translocation, the newly established colony on Boondelbah Island has produced a total of 24 eggs and 14 fledglings. The translocation technique developed for Gould’s petrel has broad applicability, being readily adaptable for other burrow-nesting seabirds.

International audience; This study describes and compares the pelagic distribution and migratory patterns of the two subspecies ofGould’s Petrel (Pterodroma leucoptera), and contrasts data obtained from tracking birds at sea using geolocators withobservational data (shipboard sightings, by-catch records and beachcast specimens). While breeding, tracked individuals ofboth subspecies (P. l. leucoptera and P. l. caledonica) foraged within the Tasman Sea and south of the Australian continent,with forays west into the Indian Ocean before laying. After breeding, both subspecies migrated to distinct non-breedingranges within the eastern tropical Pacific Ocean. Observational data identified the general pattern of migration and foragingareas of the species, whereas data from geolocators provided details of routes and timing of migration, core foraging ranges,and marked spatial and temporal segregation between the two subspecies. However, by attaching geolocators only toestablished breeders, as is typical of studies of small and medium-sized seabirds, these devices failed to identify that nonbreedingbirds (pre-breeders and adults that are deferring breeding) may not follow the same migratory schedules or have thesame at-sea distribution. We conclude that integrating data from electronic tracking with observational data substantiallyimproves our understanding of the pelagic distribution of seabird populations.

Aside from a few pairs recently discovered breeding on nearby Boondelbah Island, the Gould’s Petrel (Pterodroma leucoptera leucoptera) is limited to a single breeding colony located on Cabbage Tree Island, New South Wales. The translocation of birds from Cabbage Tree Island to establish a new colony elsewhere, or to augment the small colony on Boondelbah Island, is an option currently being considered to aid the long-term conservation of this endangered species. We undertook a trial translocation of nestlings within their current breeding grounds on Cabbage Tree Island. This involved removal of the nestlings from the natal nest, denying them further parental care, relocating them to an artificial nest box and feeding them artificially. Thirty nestlings were translocated between gullies on Cabbage Tree Island after they had attained specific plumage characteristics thought to occur just prior to their first emergence from their nests. The translocated nestlings were confined to their adopted nest boxes for the first 3 days and artificially fed every third day until they fledged. The experimental translocation and the associated use of artificial feeding resulted in a small increase in fledging weight, but caused no reduction in fledging success, and had no effect on the timing of departure of the fledglings. Three translocated fledglings have returned to Cabbage Tree Island since their departure in April 1995; all returned to their adopted nest site, one being recovered only a few metres from the nest from where it fledged. This study demonstrated that translocations of Gould’s Petrel nestlings can be achieved without any discernible detriment to the individual birds involved.

The endangered Gould's petrel ( Pterodroma leucoptera leucoptera ) nests, almost exclusively, in rainforest on Cabbage Tree Island, New South Wales, Australia. Since their introduction in 1906, European rabbits ( Oryctolagus cuniculus ) have greatly changed the structure of the rainforest, threatening its existence and that of the petrel. Rabbits were eradicated by sequential epizootics of myxomatosis and rabbit haemorrhagic disease (RHD), and a single application of cereal-based bait (Talon® 20P) containing the anticoagulant brodifacoum. The effectiveness of these mortality agents was evaluated by monitoring 70 telemetered rabbits, half of which were vaccinated against RHD. A natural epizootic of myxomatosis from May to July 1997 reduced the rabbit population from about 250 to 100. RHD, released in August 1997, reduced the population by a further 55%, the rabbits dying within 4–23 days. No survivors tested positive to RHD antibodies. Aerial baiting in September 1997 eradicated all remaining rabbits within 13 days. Intensive monitoring over the next 6 months detected no survivors. Non-target deaths included two buff-banded rails ( Gallirallus philippensis ) and one pied currawong ( Strepera graculina ).

The remains of adult Gould's Petrels Pterodroma leucoptera leucoptera were recovered from the nesting site on Cabbage Tree Island, New South Wales. Entanglement in the sticky fruits of the Bird-lime Tree Pisonia urnbellifera was identified as a major cause of mortality. Removal of P. urnbellifera eliminated one cause of death but mortality of adult petrels continued at an unsustainable rate as the result of predation by the Pied Currawong Strepera graculina. Hunting and feeding behaviour of the Pied Currawongs were observed, including holding fast a petrel carcass while ripping flesh from the skeleton. Mortality of Gould's Petrels subsided immediately following the destruction of Pied Currawong nests and nestlings. Subsequent recurrences of predation were correlated with additional nesting attempts by Pied Currawongs but declined substantially following the instigation of a control program for Pied Currawongs on Cabbage Tree Island. Pied Currawongs take the eggs and nestlings of many species of birds, but losses of nesting adults or the decline of a seabird have not been attributed previously to currawong predation.

The only population of Gould's Petrel Pterodroma leucoptera leucoptera has declined substantially during the last few decades. Adult mortality has been high, and has exceeded potential recruitment. Breeding success has been low. Entanglement in the sticky fruits of the Birdlime Tree Pisonia umbellifera and predation by Pied Currawongs Strepera graculina and Australian Ravens Corvus coronoides have been the major causes of petrel mortality on land. Experimental management actions aimed at ameliorating these threats were implemented, and their efficacy assessed. The removal of Pisonia and the control of avian predators dramatically lessened the mortality of Gould's Petrels ashore on Cabbage Tree Island. Instigation of these management actions in 1993 was coincident with a 68% rise in the number of birds brooding eggs in mid-December. Further small increases in the breeding population occurred in subsequent years. Management of the colony was also coincident with a substantial increase in breeding success (up from 25% to 45%). Breeding success increased to 59% in the 1994?95 season, but declined to 26% during 1995?96. Prior to management of the colony, an average of 30 birds fledged per annum (range 23?40; n= 4); after management, this rose to 167 per annum (range 105?233; n= 3). Management of the colony appears the most likely cause of this turnaround, but the possibility of it being due to extraneous factors such as weather or oceanographic perturbations cannot be excluded. The threats posed by Pisonia umbellifera and avian predators were, together, sufficient to account for the decline of Gould's Petrel. The demonstration that these two threatening processes can be ameliorated successfully suggests a high potential for recovery of the species.

Gould's petrel, Pterodroma leucoptera leucoptera, breeds only on Cabbage Tree Island, New South Wales. Annual surveys to estimate the size of the breeding population and the reproductive output were conducted between 1989 and 1992. Annual estimates of the total number of pairs breeding in the two gullies containing the main population were between 122 +/- 20 (s.e.) and 202 +/- 26. Breeding success was less than 20% between 1989 and 1991, but rose to 24.7% in 1992. This marginal improvement may be the result of management action undertaken to reduce mortality of breeding adults and fledglings. The total population is estimated to have declined from 2004 (95% confidence limits: 1464,3185) in 1970 to 1479 (1250,1815) in 1992, a decline of 26% in 22 years. The reasons for this decline are unclear.