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We report the depredation by a single Eastern Barn Owl Tyto javanica delicatula on prospecting White-faced Storm Petrels Pelagodroma marina during the re-establishment phase of a colony on Big Island, off Port Kembla, New South Wales, Australia in 2018. Storm petrels were likely extirpated from this colony 56 years previously when invasive weeds rendered their habitat inaccessible. Restoration of vegetation together with storm petrel call broadcasting, commencing in 2014, resulted in significant increases in prospecting numbers, culminating in breeding (three pairs) in the 2017/18 austral summer season. A significant depredation event (> 59 adults) occurred between August and September 2018, providing a set-back to colony establishment. Previously, barn owl depredation on Big Island had been limited to Silver Gulls Chroicocephalus novaehollandiae as prey. However, in the 2018/19 season, the gulls commenced nesting later than usual. The delay appeared to cause the owl to switch target prey. Despite the intense depredation pressure, at least two pairs of storm petrels attempted to breed in the 2018/19 season and 10 birds were trapped and banded at the commencement of the 2019/20 season. Discovery of the mainland roost of the owl was attempted between the two seasons, and its potential death by car strike was investigated. Our findings show that even a single individual predator can have significant impacts on seabird colonies establishing or re-establishing in island environments, especially those under restoration. [ABSTRACT FROM AUTHOR]

We present the first tracked movements of the medium-sized tropical White Tern Gygis alba, using Global Location Sensors (GLS), from a breeding colony on Lord Howe Island, South Pacific, Australia. The tracking period encompassed pre-breeding in 2018 to potential chick provisioning in the following season. Terns remained near Lord Howe Island during breeding, with some pre-egg-laying and post-nestfailure trips 1 000 km distant. The average departure date from Lord Howe Island was 08 April (range: 21 March–22 April). The tern’s migration route was northwest towards the eastern Australian coast, skirting the Great Barrier Reef. Terns then spent the non-breeding period (50% utilisation distribution) in the northwestern Coral Sea bounded by the New Guinea archipelago to the north and North Queensland, Australia, to the west. The mean transit time to the core non-breeding areas was five days (standard deviation ± 2.5 d). The core nonbreeding area was 2 200 km from Lord Howe Island. The mean time spent in the core non-breeding area was 93 d (± 10 d). The return passage completed a clockwise journey with a mean passage time of 12 d (± 3.8 d) and an average arrival on Lord Howe Island of 18 August (range: 08 August–02 September). Over 51% of their core foraging and non-breeding areas were within dedicated marine park networks. We documented the day visits to the island and approximate incubation shifts and nest attendance from changes in light levels of GLS devices. We determined, using saltwater immersion data, that the species exhibited almost no contact with the sea surface during darkness. Peak activity during daylight hours commenced at 12h00, probably indicating resting after foraging at sea. From the limited samples, instrumenting of the terns did not appear to impede breeding attempts during the 14 months of attachment. [ABSTRACT FROM AUTHOR]

On 11 July 2019, during the Rodent Eradication Program on Lord Howe Island using aerial and ground rodentbaiting, the recovery of dead non-target birds included a recently dead boobook Ninox sp. found on a resident’s property. Two Tyto species were also recovered. Despite automated sound-recording equipment stationed within the forests of the Island, no records of Ninox vocalisations were made before discovery of the boobook specimen; however, two instances of Ninox owl calls were reported anecdotally within The Settlement. There was speculation from some Island residents that the recovered boobook could have been an individual of the extinct endemic subspecies, the Lord Howe Boobook N. novaeseelandiae albaria. The boobook was forwarded to the Australian Museum for further visual scrutiny, collection of morphometric data, DNA analysis, and preparation for the Australian Museum collection. There was overlap in plumage and morphological measurements between both the Tasmanian Boobook (N. leucopsis) and the nominate Tasman Morepork from New Zealand (N. n. novaeseelandiae), but the specimen was distinct from the larger Australian mainland N. boobook. DNA analysis provided conclusive evidence that the bird was a male N. leucopsis, exhibiting an overall clean-white spotted pattern and darker brown coloration. The occurrence of a Ninox species on Lord Howe Island is the first record in more than 50 years and should prompt further exploration of the dispersal and possible migration of boobooks from Tasmania. [ABSTRACT FROM AUTHOR]

Context. For the past 50 years, rodent eradications have been conducted worldwide to reverse the devastating impacts of introduced rodents on island species. However, few studies have quantitatively measured the effects of rodent eradications on native species. Aims. This study investigated the effects of a rodent eradication on Lord Howe Island on two native birds. Methods. To mitigate the risk of Lord Howe currawongs being poisoned during baiting operations, 30-40% of the population were taken into captivity during baiting, while the remaining currawongs were left in the wild. We studied currawong survival, nesting density and breeding success pre- and post-eradication to test how the baiting, a period in captivity, and the removal of rodents affected currawongs. We also investigated breeding success of white terns as they were expected to benefit from the eradication due to predator reduction. Key results. We found that many currawongs left in the wild disappeared during the baiting period and nesting densities in one part of the island were significantly lower after the eradication. These currawongs likely died of poisoning as they were not resighted for 2 years post-eradication. White tern breeding success did not increase after the rodent eradication, although their predators were largely eliminated. Conclusions. The captive management of currawongs mitigated the adverse effects of the baiting. As those currawongs that survived had high breeding success, we predict that the population will soon recover to pre-eradication size. Implications. Our study reinforces the necessity of integrating ecological monitoring as part of future eradications on islands. [ABSTRACT FROM AUTHOR]

Reducing extinction risk is a common aim of threatened species management. However, over the period 1990 to 2020, extinction risk was recently assessed as having declined in only 25 out of the 199 Australian bird taxa eligible for assessment. Here we analyse patterns that emerge from these taxa. Some of these improvements may be only temporary; the extinction risk of three taxa increased after it had initially declined. Invasive predator control on islands was the conservation intervention with greatest impact, benefitting 13 taxa (with nine of these from Macquarie Island). For four taxa, intensive management was the primary driver of reduced risk. Another four benefited from habitat protection and one from law enforcement. For seven taxa, conservation actions had no discernible effect; for two albatrosses a shift in fishing patterns may have reduced bycatch, for one, losses on the mainland meant that most birds now persist only in a stable island population and, for four taxa, reasons for changes in population trend are unknown. Never was there only one driver of reduced extinction risk with most taxa benefitting from at least five drivers. Macquarie Island was the only geographic cluster of taxa; there was little overlap among other taxa. Although the number of improvements is small, our results demonstrate that reduced extinction risk can be achieved with the right combination of targeted actions and, in some cases, serendipity. However, due to insufficient data, our ability to predict accurately the drivers of, or changes in, extinction risk for most species remains poor. Reductions in extinction risk are rare but achievable. Up to ten different factors contributed to reduced extinction risk in a taxon; there were rarely fewer than five. Extinction risk reduction had no geographical focus apart from the cluster of taxa on Macquarie Island. There is currently no widely accepted approach to classifying the many ways in which extinction risk can be reduced. Over a quarter of risk reduction examples were not the result of conservation interventions. [ABSTRACT FROM AUTHOR]

Pterodroma leucoptera caledonica is a subspecies of Gould's Petrel endemic to New Caledonia. Its distribution, abundance and breeding biology are poorly known. Extensive surveys of New Caledonia between 1994 and 2014 located only two breeding colonies, and a further likely, but still unconfirmed; the total estimated size of the population could be of the order of 5000–7000 breeding pairs. Nesting burrows were situated either near streams or on slopes near ridges. The breeding phenology of caledonica was similar to that of the Australian leucoptera, but with a breeding calendar that lagged that of leucoptera by 2–4 weeks depending on year and breeding parameter. Breeding success was low, with evidence of a high level of predation of eggs, chicks and adults by rats, pigs and cats. Pigs also destroyed nesting burrows. Permanent bait stations installed to control rats at one colony appeared successful, but the control of pigs and cats is much more problematic. If, as expected, the level of predation observed at one colony extends across all breeding colonies, population decline is inevitable and extinction likely in the long term. With no populations of P. l. caledonica on predator-free offshore islands, translocation to such sites may be evaluated to safeguard this subspecies. In the meantime, we recommend that the global status of Gould's Petrel Pterodroma leucoptera be upgraded from Vulnerable to Endangered. [ABSTRACT FROM AUTHOR]

On isolated islands, large arthropods can play an important functional role in ecosystem dynamics. On the Norfolk Islands group, South Pacific, we monitored the diet and foraging activity of an endemic chilopod, the Phillip Island centipede (Cormocephalus coynei), and used a stable isotope mixing model to estimate dietary proportions. Phillip Island centipede diet is represented by vertebrate animals (48%) and invertebrates (52%), with 30.5% consisting of squamates, including the Lord Howe Island skink (Oligosoma lichenigera) and Günther's island gecko (Christinus guentheri); 7.9% consisting of black-winged petrel (Pterodroma nigripennis) nestlings; and 9.6% consisting of marine fishes scavenged from regurgitated seabird meals. Centipede predation was the principal source of petrel nestling mortality, with annual rates of predation varying between 11.1% and 19.6% of nestlings. This means that 2,109–3,724 black-winged petrel nestlings may be predated by centipedes annually. Petrels produce a single offspring per year; therefore, predation of nestlings by centipedes represents total breeding failure for a pair in a given year. Our work demonstrates that arthropods can play a leading role in influencing vertebrate reproductive output and modifying trophic structures and nutrient flow in island ecosystems. [ABSTRACT FROM AUTHOR]