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Summary Seabirds are highly threatened, including by fisheries bycatch. Accurate understanding of offshore distribution of seabirds is crucial to address this threat. Tracking technologies revolutionised insights into seabird distributions but tracking data may contain a variety of biases. We tracked two threatened seabirds (Salvin’s Albatross Thalassarche salvini n = 60 and Black Petrel Procellaria parkinsoni n = 46) from their breeding colonies in Aotearoa (New Zealand) to their non-breeding grounds in South America, including Peru, while simultaneously completing seven surveys in Peruvian waters. We then used species distribution models to predict occurrence and distribution using either data source alone, and both data sources combined. Results showed seasonal differences between estimates of occurrence and distribution when using data sources independently. Combining data resulted in more balanced insights into occurrence and distributions, and reduced uncertainty. Most notably, both species were predicted to occur in Peruvian waters during all four annual quarters: the northern Humboldt upwelling system for Salvin’s Albatross and northern continental shelf waters for Black Petrels. Our results highlighted that relying on a single data source may introduce biases into distribution estimates. Our tracking data might have contained ontological and/or colony-related biases (e.g. only breeding adults from one colony were tracked), while our survey data might have contained spatiotemporal biases (e.g. surveys were limited to waters

The impacts of invasive house mice Mus musculus have received increasing attention on islands where mice are the only invasive rodent species. On Gough Island, the impact of mice on seabirds has in...

We compared systematic and random survey techniques to estimate breeding population sizes of burrow-nesting petrel species on Marion Island. White-chinned (Procellaria aequinoctialis) and blue (Halobaena caerulea) petrel population sizes were estimated in systematic surveys (which attempt to count every colony) in 2009 and 2012, respectively. In 2015, we counted burrows of white-chinned, blue and great-winged (Pterodroma macroptera) petrels within 52 randomized strip transects (25 m wide, total 144 km). Burrow densities were extrapolated by Geographic Information System-derived habitat attributes (geology, vegetation, slope, elevation, aspect) to generate island-wide burrow estimates. Great-winged petrel burrows were found singly or in small groups at low densities (2 burrows ha−1); white-chinned petrel burrows were in loose clusters at moderate densities (3 burrows ha−1); and blue petrel burrows were in tight clusters at high densities (13 burrows ha−1). The random survey estimated 58% more white-chinned petrels but 42% fewer blue petrels than the systematic surveys. The results suggest that random transects are best suited for species that are widely distributed at low densities, but become increasingly poor for estimating population sizes of species with clustered distributions. Repeated fixed transects provide a robust way to monitor changes in colony density and area, but might fail to detect the formation/disappearance of new colonies.

1. The identification of geographic areas where the densities of animals are highest across their annual cycles is a crucial step in conservation planning. In marine environments, however, it can be particularly difficult to map the distribution of species, and the methods used are usually biased towards adults, neglecting the distribution of other life-history stages even though they can represent a substantial proportion of the total population. 2. Here we develop a methodological framework for estimating populationlevel density distributions of seabirds, integrating tracking data across the main life-history stages (adult breeders and non-breeders, juveniles and immatures). We incorporate demographic information (adult and juvenile/immature survival, breeding frequency and success, age at first breeding) and phenological data (average timing of breeding and migration) to weight distribution maps according to the proportion of the population represented by each life-history stage. 3. We demonstrate the utility of this framework by applying it to 22 species of albatrosses and petrels that are of conservation concern due to interactions with fisheries. Because juveniles, immatures and non-breeding adults account for 47%–81% of all individuals of the populations analysed, ignoring the distributions of birds in these stages leads to biased estimates of overlap with threats, and may misdirect management and conservation efforts. Population-level distribution maps using only adult distributions underestimated exposure to longline fishing effort by 18%–42%, compared with overlap scores based on data from all lifehistory stages. 4. Synthesis and applications. Our framework synthesizes and improves on previous approaches to estimate seabird densities at sea, is applicable for data-poor situations, and provides a standard and repeatable method that can be easily updated as new tracking and demographic data become available. We provide scripts in the R language and a Shiny app to facilitate future applications of our approach. We recommend that where sufficient tracking data are available, this framework be used to assess overlap of seabirds with at-sea threats such as overharvesting, fisheries bycatch, shipping, offshore industry and pollutants. Based on such an analysis, conservation interventions could be directed towards areas where they have the greatest impact on populations. Fundação para a Ciência e a Tecnologia - FCT; French Polar Institute IPEV; Falkland Islands Government info:eu-repo/semantics/publishedVersion

Populations of grey petrels have declined globally due to both incidental capture in commercial fisheries and predation by introduced mammals at breeding sites. In the New Zealand region, grey petrels only breed on Campbell and Antipodes islands. Rats were successfully eradicated from Campbell Island in 2001. We assessed the spatial extent and conducted the first quantitative population estimate of the grey petrel population on Campbell Island and surrounding islets. There was an estimated c. 96 pairs (95% CI: 83, 109) of breeding grey petrels from the four colonies. Since work was conducted during the middle of the chick-rearing stage, this is an underestimate of the breeding population. The Campbell Island grey petrel breeding population remains small. Our study provides a baseline for future population estimates of grey petrels on Campbell Island.

The Southern Ocean represents a continuous stretch of circumpolar marine habitat, but the potential physical and ecological drivers of evolutionary genetic differentiation across this vast ecosystem remain unclear. We tested for genetic structure across the full circumpolar range of the white-chinned petrel (Procellaria aequinoctialis) to unravel the potential drivers of population differentiation and test alternative population differentiation hypotheses. Following range-wide comprehensive sampling, we applied genomic (genotyping-by-sequencing or GBS; 60,709 loci) and standard mitochondrial-marker approaches (cytochrome b and first domain of control region) to quantify genetic diversity within and among island populations, test for isolation by distance, and quantify the number of genetic clusters using neutral and outlier (non-neutral) loci. Our results supported the multi-region hypothesis, with a range of analyses showing clear three-region genetic population structure, split by ocean basin, within two evolutionary units. The most significant differentiation between these regions confirmed previous work distinguishing New Zealand and nominate subspecies. Although there was little evidence of structure within the island groups of the Indian or Atlantic oceans, a small set of highly-discriminatory outlier loci could assign petrels to ocean basin and potentially to island group, though the latter needs further verification. Genomic data hold the key to revealing substantial regional genetic structure within wide-ranging circumpolar species previously assumed to be panmictic. Fundação para a Ciência e Tecnologia - FCT info:eu-repo/semantics/publishedVersion

The white-chinned petrel Procellaria aequinoctialis is one of the most frequently observed seabird species captured in fisheries bycatch, yet some populations remain virtually unstudied. The size of the breeding population on the sub-Antarctic Auckland Islands, New Zealand, is unknown. Disappointment Island is thought to be the main white-chinned petrel breeding site in the Auckland Islands, and maybe also in the New Zealand region, and has never had introduced mammalian predators. We estimated the white-chinned petrel breeding population size taking into account the detection probability of burrows via distance sampling and the burrow occupancy rate. Eighty line transects were distributed over the island, with a total line length of 1600 m. Burrows were patchily distributed and most abundant in dense megaherb communities. White-chinned petrel burrow density $$ \hat{D } $$ was 654 burrows/ha (95 % CI 528–809 burrows/ha), with burrow detection probability $$ \hat{p} $$ varying among vegetation communities from 0.28 ± 0.02 to 0.43 ± 0.02 (±SE). Mean burrow occupancy was 0.73 ± 0.03. We document an estimated total of 155,500 (125,600–192,500) breeding pairs of white-chinned petrels on Disappointment Island during mid incubation in early January 2015. The relatively high occupancy and density of burrows suggest that Disappointment Island is a key breeding site for white-chinned petrels.

South Georgia has been the southernmost location where populations of invasive house mice Mus musculus are found. The distribution of mice was investigated at Cape Rosa and the Nunez Peninsula, the two areas of South Georgia where the species is known to occur. Live-trapping and kill-trapping took place during March 2012, at the end of the austral summer, with traps in four grids (3.2–4.0 ha in area) and on 34 trap lines distributed across a range of habitats from the shoreline to 250 m above sea level. Mice were scarce, with just 68 captures in about 1750 trap nights. Mouse densities in tussock habitat were estimated at 2.1–2.8 mice/ha, with higher densities of 5.3–6.4 mice/ha along the coastline. Mice were found in all habitats apart from higher-altitude fellfield, but were relatively less abundant in tussock habitat with large numbers of seals. Mice were breeding at both sites with 58 % of mature females pregnant or lactating. Litter size (7.1 ± 2.3 embryos) and adult body mass (21.4 ± 4.6 g) were typical of most other island mice populations. Population densities of mice on South Georgia are two orders of magnitude lower than mouse densities measured at other sub-Antarctic islands. The very low population density and its restricted distribution, with most captures close to the shore, and the presence of large numbers of burrowing petrels and South Georgia pipits Anthus antarcticus at both sites, suggest that mice have a relatively limited impact on South Georgia’s vertebrate biodiversity.

Background The extent to which seasonal changes in food availability affect small-scale movements in free-ranging populations of birds of prey is relatively little studied. Here we describe a seasonal “micro-migration” of a farm-island population of striated caracaras (Phalcoboenus australis) in the Falkland Islands in response to seasonal changes in the availability of seabird carcasses. We banded more than 450 individuals on Saunders Island, deployed archival and satellite GPS data loggers on 17 individuals, and monitored movements within and between two feeding areas on Saunders Island, a “marine-subsidized” site near seabird colonies and an anthropogenic “human-subsidized” farm site 16 km to the southeast. Results During 67 observation days between 2010 and 2015, resightings of 312 banded caracaras were greater at the marine-subsidized site during austral summer than winter, and the total daily resightings varied significantly between spring versus summer, summer versus winter, autumn versus spring, and autumn versus winter. Resightings were higher at the human-subsidized site in austral winter than summer and the total daily resightings varied significantly across all bi-seasonal comparisons. Resightings indicated that at least 12 of 197 birds (6.1%) moved between the human- and marine-subsidized sites at least once during the same winter, 15 of 335 birds (4.5%) did so in spring, none of 164 birds did so in summer, and 16 of 297 birds (5.4%) did so in autumn. Individuals fitted with archival GPS data loggers at the marine-subsidized site in summer maintained highly localized 95% kernel core areas (0.55 ± 0.12 km2 [mean ± SD]), whereas those at the human-subsidized site in winter maintained larger 95% kernel core areas (3.8 ± 4.6 km2). Two of 6 satellite-tagged individuals that summered at known caracara breeding colonies 80 km WNW of Saunders Island were subsequently resighted in winter at the human-subsidized site. Conclusion Our results suggest that seasonal shifts in food resource availability drive seasonal micro-migrations in a farm-island population of striated caracaras, and that farm sites can be critical in providing nutritional resources for caracaras when naturally occurring marine-subsidized resources become less available. Our results have important implications for striated caracara spatial ecology and conservation, as increased winter survival could improve the status of this globally Near-Threatened population.

The biology of littoral fauna of the Falkland Islands is largely unknown. This pilot study was launched by Shallow Marine Surveys Group and was aimed at investigating life history of the Antarctic starfish, Anasterias antarctica, a dominating invertebrate predator of intertidal and subtidal, including its distribution, seasonal and ontogenetic migrations, spawning seasonality, fecundity, growth, and feeding habits. A total of 3,426 starfish were sampled in different habitats around the Falkland Islands at low tide using SCUBA diving. Sampling included measuring arm length, presence/absence of brooding and feeding; the prey was identified to the lowest taxa and measured if condition permitted. In a total of 48 broods, eggs were counted and embryonic stage assigned. This medium-sized species attains an arm length of 96 mm (85.4 g). The size increased with depth and starfish carry out seasonal bathymetric migrations with smaller animals ( 10 m depth in winter. Egg laying occurs between March and July, and juvenile dispersal—mostly in October–November. Fecundity (52–363 eggs) and egg/offspring size increase with maternal size. Juvenile starfish are of ca. 2 mm arm length and grow to 9–11 mm in 1 year. Feeding intensity is at a maximum before and after the reproductive period. Females might occasionally resume feeding when they are still brooding a small number of juveniles. The starfish prey upon isopods (Sphaeromatidae), molluscs Pareuthria spp. and variety of gastropods, bivalves chitons, barnacles, and also scavenges. Prey size increases with starfish size.

Invasive house mice Mus musculus are known to impact on seabird, invertebrate and plant communities on temperate and subantarctic islands, particularly where they are the sole rodent species. Steeple Jason, in the Falkland Islands, is an island which supports globally important seabird populations as well as introduced mice. To evaluate the prospects for mouse eradication, we investigated mouse ecology and undertook bait uptake trials on Steeple Jason in late winter. Mice were present in all habitats but were most abundant in tussac Poa flabellata where they occurred at 20–35 mice ha−1. From 58 mature perforate females, 16 % were pregnant, with litters of 4–8 pups. The first lactating female was caught at the end of August, suggesting that breeding had recently begun. Bait trials replicating an aerial eradication were undertaken on two trapping grids of 7.7 and 6.8 ha, with non-toxic pellets containing the biomarker pyranine spread at 7.5–7.7 kg ha−1. All 447 mice captured after baiting had consumed bait. The relatively low winter density, distribution and biology of house mice on Steeple Jason are similar to those observed before other successful mice eradications, and the study indicated 100 % bait acceptance. Before an eradication attempt, we suggest investigating whether breeding ceases completely earlier in the winter and urge careful consideration of non-target species.

Introduced house miceMus musculusL. have been discovered to be major predators of chicks of the Tristan albatrossDiomedea dabbenenaL. and Atlantic petrelPterodroma incertaSchlegel and to also predate great shearwaterPuffinus gravisO'Reilly chicks at Gough Island, and similar predatory behaviour has been reported for house mice on Marion Island. Observations on Gough Island over three breeding seasons of nesting Atlantic yellow-nosed albatrossesThalassarche chlororhynchosGmelin and dark-mantled sooty albatrossPhoebetria fuscaHilsenberg indicate that house mice are also preying on these two species: the first records of mice preying upon summer-breeding albatross species on Gough Island. Predation on these two albatross species appears to be relatively rare (∼2% for the Atlantic yellow-nosed albatrosses) and ongoing monitoring is required to ascertain if the impact of mice is increasing. Conservation actions to eradicate mice from Gough Island will be of benefit to these species and other species that are being impacted by this invasive species.

SummaryThe predatory behaviour of introduced house mice Mus musculus at Gough Island is known to impact on albatross and petrels, resulting in the Tristan Albatross Diomedea dabbenena and Atlantic Petrel Pterodroma incerta being listed as “Critically Endangered” and “Endangered”, respectively. Although predation has been documented for two burrowing petrels and one albatross species, the impact of house mice on other burrowing petrels on Gough Island is unknown. We report burrow occupancy and breeding success of Atlantic Petrels, Soft-plumaged Petrels Pterodroma mollis, Broad-billed Prions Pachyptila vittata, Grey Petrels Procellaria cinerea and Great Shearwaters Puffinus gravis. With the exception of the Great Shearwater, breeding parameters of burrowing petrels at Gough Island were very poor, with low burrow occupancy (range 4–42%) and low breeding success (0–44%) for four species, and high rates of chick mortality in Atlantic Petrel burrows. Breeding success decreased with mass, suggesting that smaller species are hardest hit, and winter-breeding species had lower breeding success than summer breeders. The results indicate that introduced house mice are having a detrimental impact on a wider range of species than previously recorded and are likely to be causing population declines among most burrowing petrels on Gough Island. The very low values of burrow occupancy recorded for Soft-plumaged Petrels and Broad-billed Prions and greatly reduced abundance of burrowing petrels in comparison to earlier decades indicate that Gough Island’s formerly abundant petrel populations are greatly threatened by the impact of predatory house mice which can only be halted by the eradication of this species from the island.

Striated caracaras occur only on the Falkland Islands and the outer islands of southern Chile and Argentina. In summer, the species associates with seabirds and seals and depends heavily upon them for food. The winter diet is less well understood. We studied the diet of 90–130 mainly juvenile and sub-adult striated caracaras overwintering at a farm on Saunders Island, Falkland Islands, in mid-winter (July–August) 2011. Direct observations of feeding and regurgitation pellets collected at a roost indicate that the winter diet of the striated caracaras at the site is mainly native geese, beetles and other invertebrates, and the carcasses of domestic sheep. This study illustrates seasonal shifts in the diet of this near-threatened South Atlantic endemic and suggests an important nutritional link between juvenile and subadult caracara survival in winter and traditional human activities at sheep farms.

To examine the extent and possible causes of ringing injuries in the Gough Moorhen Gallinula comeri, ringed birds were monitored and recaptured. Of ringed Gough Moorhens, 12.5% developed injuries associated with leg rings. Injuries developed rapidly, ranging from lameness to complete crippling of the leg. Given the cryptic behaviour of Gough Moorhens and the rapid onset of injuries, long-term use of metal rings is not recommended for free-roaming Gough Moorhens. Ringing injuries have not been reported previously in rails, highlighting the need for caution when ringing previously unstudied bird species.

To develop an accurate, low-cost method for sexing Gough Moorhens Gallinula comeri using morphometric measurements, twelve measurements were taken from 59 birds and validated against genetic sexing. The classification accuracy of variables was determined and discriminant analysis was used to test whether multiple variables improved accuracy. Males were larger than females in all dimensions. Head length reliably differentiated male and female Gough Moorhens. A threshold of 64 mm correctly classified 92% of the sample birds; adding other variables did not improve accuracy. Gough Moorhens can be sexed with an acceptable level of accuracy using a single morphometric variable, but genetic sexing is needed to confirm the sex of individuals that fall within the overlap zone (62–66 mm).

The brown tree frog (Litoria ewingii) is the only known Southern Hemisphere vertebrate that can survive full-body freezing. Freezing challenges living organisms in many ways, with ice formation in the body producing a suite of physical and metabolic stresses which can damage cells and tissues. The present study looked at two mechanisms that address some of these stresses: cryoprotectants and ice nucleating agents (INAs). Skin secretions from L. ewingii were sampled along with microhabitat substrate and tested for the presence of INAs, which help control ice formation in the body. L. ewingii plasma was tested for seasonal and freezing-induced changes in both glucose and glycerol, which may have a cryoprotective role in freezing-tolerant frogs. Glycerol levels increased on freezing and decreased on thawing, while glucose levels did not change on freezing but increased on thawing. This suggests that glycerol may be acting as a cryoprotectant, although levels are low compared to other frogs. A clear seasonal change was seen in INA activity, with greater activity in winter than in summer. While potent INAs came from the microhabitat substrate, this work has shown for the first time that skin secretions also contain active INAs.