Search

Saunders’s terns (Sternula saundersi) are a small, ground-nesting marine bird species that have a massive rearing range, including the shores and islands of Asia and Africa adjacent to the north Indian Ocean. Despite occupying a large breeding range, little is known about the breeding ecology of this species. This research explored aspects of Saunders’s terns’ breeding ecology and predation rate in 2013 on the Farasan Islands of Saudi Arabia. The outcomes confirm that the mean clutch size of a Saunders’s tern was 1.77 ± 0.08 (n = 31) eggs per clutch and the mean egg size was 31.05 × 23.15 mm. The results of this study show a remarkable relationship between clutch size and egg volume and length (p = .002, p = .004, respectively). Predation was the major reason for nest damage (62.5%). Evidence from cameras at nests showed that the predators of Saunders’s tern nests on the Farasan Islands were white-tailed mongoose (Ichneumia albicauda) and Egyptian vultures (Neophron percnopterus). This is the first study on the breeding ecology of Saunders’s terns, and it shows that predator control is essential to the existence of the species. The results of this study suggest that fencing some breeding sites may help to minimize human disturbance and decrease the risk of nest predation from mammalian predators. Further research is needed to compare the predation rates on the mainland and islands and to develop efficient strategies to conserve this ground-nesting species.

The arctic tern (Sterna paradisaea) is a ubiquitous migratory seabird of the High Arctic, currently thought to be in decline in most of the circumpolar world, but surprisingly little is known of its biology at high latitudes. We studied organ size and nutrient reserves of arctic terns breeding beside a High Arctic polynya in Nunavut, Canada, from their arrival at the colony into the chick-rearing period. Both males and females had a decrease in gizzard size through breeding, with gizzard mass during chick-rearing 39 percent lower than on arrival at the breeding grounds. Through the duration of the breeding season, heart, liver, and small intestine showed little change, but females had higher fat and protein stores than males. Terns from this colony likely have increasing fat levels and high body condition due to proximity to a highly productive polynya, where terns appear to gain more energy than they expend during foraging trips. This suggests that though terns at this colony may be near the northern limit of their range, local conditions have a strong impact on organ and nutrient reserve dynamics of these arctic seabirds.

Determining the migratory status of seabird populations is crucial for addressing conservation concerns. The Roseate Tern Sterna dougallii is considered endangered in South Africa in view of its small breeding population and the threats to eggs and chicks. Earlier works based on capture-recapture data suggest that this population adopts a partial migratory strategy. Updated capture-recapture data were combined with new data on moult and stable isotopes of scapular feathers to determine whether subpopulations could be identified in the South African breeding population. Moult data on 404 individuals failed to identify subpopulations, but two groups were identifiable with the stable isotopes: one group of four individuals exhibiting low carbon and nitrogen stable isotope ratios and a second group (comprising the remaining 152 individuals) with significantly higher ratios. The isotope data suggest that birds from the two groups moulted in different areas. Comparisons with published studies showed that the 152 individuals had likely moulted their scapulars in South African waters, but the moulting area for the remaining four individuals could not be ascertained due to the absence of detailed isoscapes in the southern part of the Mozambique Channel. Further work investigating the genetic differentiation between South African and Madagascan Roseate Terns may bring new insight into the migratory behaviour of the South African population. Sternes de Dougall Sterna dougallii sur la côte sud-est de l’Afrique du Sud: informations sur la mue et le statut de migrationDéterminer le statut de migration des populations d’oiseaux marins est crucial pour les problèmes de conservation. La Sterne de Dougall Sterna dougallii figure sur la liste des espèces en voie de disparition en Afrique du Sud, compte tenu de sa petite population reproductrice et des menaces pesant sur ses pontes et ses poussins. Des travaux antérieurs basés sur des données de capture-recapture suggèrent que cette population adopte une stratégie de migration partielle. Des données de capture-recapture actualisées ont été combinées avec des données d’isotopes stables et de mue pour déterminer si des sous-populations pouvaient être identifiées dans la population reproductrice sud-africaine. Les données de mue recueillies sur 404 individus n’ont pas permis d’identifier de sous-populations, mais deux groupes étaient identifiables avec les isotopes stables: un groupe de quatre individus présentant des ratios d’isotopes stables à faible teneur en carbone et en azote et un second groupe comprenant les 152 individus présentant des ratios beaucoup plus élevés. Les données isotopiques suggèrent que les oiseaux des deux groupes ont mué dans des zones différentes. Une comparaison avec de précédentes études publiées a montré que les 152 individus avaient probablement mué leurs scapulaires dans les eaux sud-africaines. La zone de mue des quatre individus restants n’a pas pu être déterminée en raison de l’absence d’empreintes isotopiques «isoscapes» détaillées dans le sud du chenal du Mozambique. Des travaux ultérieurs, notamment la différenciation génétique entre les sternes de Dougall sud-africaines et malgaches, pourraient apporter de nouvelles informations sur le comportement migratoire de la population sud-africaine. Keywords: Algoa Bay, coastal seabird, feathers, plumage characteristics, ringing data, stable isotopes

International audience; The eradication of invasive mammals on islands is important for protecting seabird populations and insular ecosystems. However, the impacts of such eradications are insufficiently known because monitoring of potentially beneficiary species is often sporadic and limited. We performed a survey of all seabird species on Saint-Paul Island, southern Indian Ocean, 20 years after successful eradication of invasive black rat (Rattus rattus) and European rabbit (Oryctolagus cuniculus). Using complementary sampling designs including adaptive cluster sampling, stratified random sampling and entire sampling, we estimated population changes and colonization by new seabird species. A total of 13 seabird species were found breeding on Saint-Paul post-eradication compared to six before the eradication. Among the seven species that colonized the island, five (MacGillivray’s prion Pachyptila macgillivrayi, fairy prion P. turtur, white-bellied storm petrel Fregetta grallaria, Antarctic tern Sterna vittata, sooty tern Onychoprion fuscatus) had relictual populations breeding on a nearby islet, and one (brown skua Catharacta antarctica) was a new breeding species. We also found breeding subantarctic little shearwaters Puffinus elegans. For species that were breeding on the Saint Paul pre-eradication, the mean annual population growth rate was 1.030 ± 0.093 (SE). Species known to be vulnerable to rat predation (prions, great-winged petrel Pterodroma macroptera, flesh-footed shearwater Puffinus carneipes, subantarctic little shearwater, white-bellied storm petrel, Antarctic tern) had the highest population growth rates. Two decades after the eradication of invasive mammals on a remote oceanic island, seabird populations were high beneficiaries. These findings further highlight the importance of invasive mammal eradication on islands as a conservation tool. Results are encouraging for the planned eradication of invasive mammals from nearby Amsterdam Island, and suggest this will mainly benefit terns and small burrowing petrels.

Despite intensive management since the 1970s, recovery of the endangered northwestern Atlantic population of the Roseate Tern (Sterna dougallii dougallii) has not offset low productivity from a female-biased sex ratio, low adult survival, and habitat constriction. Now, >90% of individuals breed at three sites within 200 km from Long Island, NY, to Buzzards Bay, MA (warm-water subregion). To characterize the impact of historical bottlenecks, metapopulation structure, and demographic fluctuations on genetic variation, Roseate Terns from the warm-water (1870s, 1970s, 1997, 2016) and cold-water (Nova Scotia, Canada; 2018) subregions were genotyped at 8–16 microsatellites and 2–3 mitochondrial regions. Diversity declined in the warm-water subregion from the 1870s (expected heterozygosity [HE] = 0.44, allelic richness [AR] = 2.86) and 1970s (HE = 0.53, AR = 3.25) to 1997 (HE = 0.38, AR = 2.58). Genetic signatures of bottlenecks persisted in 1997 (P =

Ruddy Turnstones Arenaria interpres have been identified as egg-predators at seabird and shorebird colonies, including gull and tern colonies in the tropics and Northern Hemisphere. The Australian Fairy Tern Sternula nereis nereis is a threatened (Environment Protection and Biodiversity Conservation Act 1999: Vulnerable) coastal seabird, whose breeding behaviour and ecology expose it to a wide range of threats. This study describes inferred predation on Fairy Tern eggs at a small breeding colony on Rottnest Island, Western Australia, by Ruddy Turnstones, a previously unsuspected predator for thisspecies. Unlike the behavioural response shown towards Silver Gulls Larus novaehollandiae and Australian Ravens Corvus coronoides, which includes collective group defence and dive-bombing, Fairy Terns showed a lack of aggression towards Turnstones within the colony. The lack of a behavioural response suggests that the Terns did not recognise the Turnstones as predators, which may increase the risk of egg-predation. This study suggests that we should be alert to threats from unsuspected predators, which have the potential to reduce the breeding success of this Vulnerable tern.

Light-level geolocators are increasingly popular devices for tracking migratory birds. However, to ensure that data on migratory behaviour represent natural behaviour that is not affected by potentially harmful effects of carrying such a device, their effects on behaviour and fitness should be assessed. A review of studies that tested for effects of tarsus-mounted light-level geolocators on seabirds showed that results are equivocal and often difficult to interpret due to the inclusion of only few traits and/or the lack of a proper experimental design. We therefore experimentally tested whether tarsus-mounted light-level geolocators affected a long-distance migratory seabird, the Common Tern Sterna hirundo. Using a well-matched treatment and control group, including both males and females, we tested whether light-level geolocators, deployed in the second half of incubation, affected the subsequent share of incubation, provisioning rate, reproductive performance, phenology or survival of tagged birds or their partners. In the year of deployment, we found no evidence for the behaviour of tagged birds or their partners to be affected by the geolocators. Moreover, we found no effect on their reproductive performance and departure date from the breeding colony. Finally, neither local survival to the next season, nor arrival date to the breeding colony in that season differed between tagged birds or their partners and control birds. These results suggest that a year of carrying a light-level geolocator attached to the tarsus has negligible effects on Common Terns and that such a device can be used to study their migratory behaviour without causing problems or introducing bias.

[In 2008-2014 wader and seabird nesting pairs were censused along the 220-km long coastline of the NE Adriatic Sea, in the Veneto and Friuli-Venezia Giulia regions (NE Italy). Fourteen species were regularly breeding, with an annual mean of 20,610 pairs (±1553, 1 SD). The most abundant species was the Yellow-legged Gull (about 13,400 pairs on average, 65% of the whole population of the study area), followed by the Common Tern (1670 pairs, 8.1%) and Common Redshank (1525 pairs, 7.4%). The whole population of waders and seabirds increased with an annual rate, estimated with the TRIM software, of +0.8%, with a greater increase (+4.3%) if the Yellow-legged Gull was not included. Twelve species were stable or increasing; only the yellow-legged gull (-1%) and the common redshank (-2.4%) were decreasing. The populations of several species exceed 10% of those estimated for the whole of Italy; those of the Eurasian Oystercatcher, Common Redshank and Sandwich Tern are among the most important in the whole Mediterranean. On average, about 8860 pairs (43%) nest in the Venice lagoon, 6,400 pairs (31%) in the Po Delta, 5100 pairs (25%) in the Friuli-Venezia Giulia lagoons. Among nesting habitats, semi-natural (such as the fish farms) and man-made sites (dredge islands) make each year about 70% of the nesting pairs. Saltmarsh islets host large numbers of Common Redshank and Sandwich Tern, while along the beach zone the only abundant species are the Yellow-legged Gull and the Eurasian Oystercatcher. The major conservation threats observed in the study area were the erosion of littoral islands, the uncontrolled occurrence of sunbathers along the beaches, the vegetation overgrowth at dredge islands, the increasing frequency of saltmarsh submersion by high tides, the strong fluctuations of water levels inside the fish farms.] [Article in Italian]

Understanding sex differences in foraging behaviour has important implications for breeding biology and population ecology. This requires the evaluation of segregation throughout the annual cycle, including the non-breeding period. We studied the diet and foraging strategies of the Common Tern (Sterna hirundo) at an intraspecific level by sampling birds during two consecutive non-breeding periods in Punta Rasa, Buenos Aires Province, Argentina. Blood samples were taken for sex determination and carbon and nitrogen stable isotope analysis. No isotopic difference was observed between years, but higher isotopic values occurred during late non-breeding period. Carbon and nitrogen isotopic values were similar between sexes; however, differences were observed in standard ellipse analyses, considered to represent isotopic niches. Even though the Bayesian ellipse areas overlapped, females showed wider isotopic niches throughout the non-breeding period. This could be related to different feeding strategies, foraging areas or migratory stopover sites at either intraspecific or individual levels. Diet contributions of different prey categories estimated through mixing model analyses suggested a higher contribution of estuarine fish than of marine pelagic species. These results highlight the importance of stable isotope analyses as a complementary methodology to traditional diet studies, particularly during the non-breeding period. Fil: Lamacchia, Paola. Universidad Nacional de Mar del Plata. Facultad de Cs.exactas y Naturales. Departamento de Biología. Laboratorio de Vertebrados; Argentina Fil: Madrid, Enrique Alberto. Universidad Nacional de Mar del Plata. Facultad de Cs.exactas y Naturales. Departamento de Biología. Laboratorio de Vertebrados; Argentina Fil: Mariano y Jelicich, Rocío. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentina

SummaryThe Chinese Crested TernThalasseus bernsteini(CCT) is likely the most critically endangered seabird species in Asia. The Matsu, Penghu, Jiushan, and Wuzhishan Archipelagos along the China coastline, plus Yeonggwang County in South Korea, are the five areas where this species is currently confirmed to breed. According to census and historical data collected in the Matsu Archipelago from 2004 to 2017, there was an average of 10 ± 4 adult CCT individuals at the Matsu Islands Tern Refuge (MITR) during the breeding season. CCT nested only in association with Greater Crested TernsT. bergii(GCT) among seven protected islands in the MITR, and the numbers of observed breeding individuals of the two species were positively correlated (r = 0.59,P< 0.001). We used generalized linear models to examine the effects of chlorophyll-a concentrations in surrounding marine habitats, typhoon frequency, and in-season shifts in colony location on inter-annual variation in numbers of breeding individuals and productivity (chick:adult ratios) of both CCT and GCT at the MITR from 2004 to 2017. Average chlorophyll-a concentrations during July-August obtained from the MODIS satellite were positively correlated with the annual maximum number of GCT at the MITR, but not that of CCT. In addition, we found that nest abandonment events during early incubation at the mixed-species colonies were associated with in-season shifts in colony location and delayed nesting chronology, thereby extending nesting into the peak typhoon season during July and August. The effects of in-season colony shifts on nesting chronology and the additive effects of typhoons caused a significant decline in CCT breeding success during the study period. We propose more rigorous monitoring to ascertain the root causes of in-season colony shifts of terns and then determine possible solutions. Additionally, creating educational programmes to increase public awareness towards seabird conservation could prove beneficial.

Seabird eggs are considered a favourable matrix for monitoring marine pollutants and are widely used as higher trophic level indicators. Concentrations of Polycyclic aromatic hydrocarbons (Σ15PAH) were determined in the eggs of four piscivorous seabirds in Ireland from multiple colonies for the first time, Common Guillemot Uria aalge, Northern Gannet Morus bassanus, Common Tern Sterna hirundo and Arctic Tern S. paradisaea. PAH concentrations were generally lower than levels detected in eggs from other seabird studies and considerably lower than concentrations associated with no adverse effect in the eggs of domestic avian species. This study indicates potential site and species differences in PAH concentrations. Baseline data of PAHs in a range of seabird species from this study may provide an important reference point should a major pollution event occur in European waters, such as an oil spill.

Understanding physical mechanisms underlying seabird foraging is fundamental to predict responses to coastal change. For instance, turbulence in thewater arising from natural or anthropogenic structures can affect foragingopportunities in tidal seas. Yet, identifying ecologically important localizedturbulence features (e.g. upwellings approximately 10–100 m) is limited byobservational scale, and this knowledge gap is magnified in volatile predators. Here, using a drone-based approach, we present the tracking of surface-foraging terns (143 trajectories belonging to three tern species) and dynamicturbulent surface flow features in synchrony. We thereby provide the earliestevidence that localized turbulence features can present physical foragingcues. Incorporating evolving vorticity and upwelling features within ahidden Markov model, we show that terns were more likely to activelyforage as the strength of the underlying vorticity feature increased, whileconspicuous upwellings ahead of the flight path presented a strong physicalcue to stay in transit behaviour. This clearly encapsulates the importance ofprevalent turbulence features as localized foraging cues. Our quantitativeapproach therefore offers the opportunity to unlock knowledge gaps inseabird sensory and foraging ecology on hitherto unobtainable scales.Finally, it lays the foundation to predict responses to coastal change toinform sustainable ocean development.

Vibrio cholerae is an inhabitant of aquatic environments worldwide. Here, we report the draft genome sequences of eight V. cholera non-O1, non-O139 isolates that were recovered from the corpses of two seabird chicks (common terns) following a mass mortality event in a German breeding colony in 2019.

Wailagilala is one of two ‘true’ atolls in Fiji. Our findings confirm the presence of nesting green turtle (Chelonia mydas); continued occurrence of breeding seabird populations, including documenting the fifth site in Fiji of nesting white tern (Gygis alba); and provides data on coral genera and benthic cover.

The Great Barrier Reef is an iconic ecosystem, known globally for its rich marine biodiversity that includes many thousands of tropical breeding seabirds. Despite indications of localized declines in some seabird species from as early as the mid‐1990s, trends in seabird populations across the reef have never been quantified. With a long history of human impact and ongoing environmental change, seabirds are likely sentinels in this important ecosystem. Using 4 decades of monitoring data, we estimated site‐specific trends for 9 seabird species from 32 islands and cays across the reef. Trends varied markedly among species and sites, but probable declines occurred at 45% of the 86 species‐by‐site combinations analyzed compared with increases at 14%. For 5 species, we combined site‐specific trends into a multisite trend in scaled abundance, which revealed probable declines of Common Noddy (Anous stolidus), Sooty Tern (Onychoprion fuscatus), and Masked Booby (Sula dactylatra), but no long‐term changes in the 2 most widely distributed species, Greater Crested Tern (Thalasseus bergii) and Brown Booby (Sula leucogaster). For Brown Booby, long‐term stability largely resulted from increases at a single large colony on East Fairfax Island that offset declines at most other sites. Although growth of the Brown Booby population on East Fairfax points to the likely success of habitat restoration on the island, it also highlights a general vulnerability wherein large numbers of some species are concentrated at a small number of key sites. Identifying drivers of variation in population change across species and sites while ensuring long‐term protection of key sites will be essential to securing the future of seabirds on the reef., Article Impact Statement: Four decades of monitoring reveals troubling trends for seabird breeding populations across the Great Barrier Reef.

Mercury (Hg), particularly as methylmercury (MeHg), is a nonessential, persistent, and bioaccumulative toxic element with high biomagnification capacity and is considered a threat to marine environments. We evaluated total Hg concentrations in liver, kidney, and brain in 62 individuals of 9 bird species linked to marine ecosystems from western Mediterranean admitted in a Wildlife Rehabilitation Center (WRC) (Alicante, Spain, 2005–2020). Age- and sex-related differences in Hg levels, as well as the cause of admission to the WRC, were also evaluated in certain species. The species studied were: northern gannet (Morus bassanus), European shag (Phalacrocorax aristotelis), great cormorant (Phalacrocorax carbo), osprey (Pandion haliaetus), Balearic shearwater (Puffinus mauretanicus), yellow-legged gull (Larus michahellis), razorbill (Alca torda), common tern (Sterna hirundo), and black-headed gull (Chroicocephalus ridibundus). Concentrations in feathers of 27 individuals, and concentrations in internal tissues in 7 other individuals of 7 different species were also reported but not statistically evaluated due to the limited number of samples. Results suggest that individuals were chronically exposed to Hg through diet. The differences in Hg concentrations among species may be explained by their diet habits. Mercury concentrations strongly correlated between tissues (r = 0.78–0.94, p

Defining a species’ ecological niche is not a trivial task particularly for marine taxa, since physical and biological constraints are not easily perceived in these environments. Yet, coastal habitats are divided into provinces, influenced by different environmental conditions, such as superficial marine currents, causing seasonality in marine productivity and biomass. The South American Tern Sterna hirundinacea is a poorly known, migratory seabird distributed along the Pacific and Atlantic coasts of South America, including the Malvinas/Falkland Islands, and occurring in most of the South American coastal provinces. Limited knowledge on the migratory behaviour of the species points to differential habits between southern and northern populations. The species’ breeding season also varies with latitude and season, occurring during spring in the south and in the fall in northern areas of the species occurrence. These observations point to putatively ecologically distinct populations along the species range that seem to be coincident with coastal provinces. To test our hypotheses, we estimated full-range ecological niche models per season, and we used coastal provinces to model ecological niches for each of the known breeding areas/seasons. We also tested for environmental space differentiation between seasons and breeding and non-breeding areas. Overall, the species does not seem to occupy significantly different ecological niches throughout the year, except during the breeding season, particularly between the Warm Temperate Southeastern Pacific and Warm Temperate Southwestern Atlantic provinces in fall. This suggests that the South American Tern migratory behaviour, the selection of different microhabitats and reproductive areas or distinct biological interactors might be influencing the species environmental space. Nonetheless, our models reinforce the gradual migration of this tern species towards the south, spending the summer mostly in the Malvinas/Falkland Islands. Interestingly, the species seems to be resident in Peru coastal area. Thus, despite the absence of ecological divergence, population structure should be tested and demographic trends assessed along the species range.

Resumen: Entre los días 24 al 27 de enero de 2019, se navegó el mar de islas Desertores, comuna de Chaitén, en la región de Los Lagos, sur de Chile. Esto con el objetivo de i) estimar la riqueza y abundancia de aves y mamíferos marinos del área de influencia de estas islas, junto con ii) identificar sitios de reproducción. Así, se realizaron registros sobre riqueza, abundancia y distribución espacial de las aves y mamíferos marinos observados durante la navegación, como así también mediante recorridos a pie en islote Nihuel (42,626° S; 72,933° O) e islote Barraco (42,737° S; 73,065° O). Se determinó que las especies gaviota cahuil (Chroicocephalus maculipennis), cormorán imperial (Leucocarbo atriceps), gaviota dominicana (Larus dominicanus) y blanquillo (Podiceps occipitalis), fueron las aves costeras más abundantes. Mientras que el lobo marino común (Otaria flavescens) y delfín austral (Lagenorhynchus australis), fueron los mamíferos marinos más abundantes. A nivel espacial, las mayores concentraciones de aves y mamíferos marinos se encontraron en los islotes Nihuel y Barraco, como así también en el litoral de isla Talcán. En el islote Nihuel nidifican al menos 2.100 parejas de cormorán imperial, lo que convierte a este lugar en uno de los sitios reproductivos más importantes para dicha especie en Chile. Así también, existe una colonia reproductiva de lobo fino austral (Arctocephalus australis), compuesta por al menos 890 individuos. Por otra parte, el islote Barraco es utilizado por gaviotines sudamericanos (Sterna hirundinacea) como sitio de nidificación, junto a un interesante grupo de aves playeras migratorias.

A broad suite of 87 contaminants of emerging concern (CECs), including 26 polybrominated diphenyl ethers (PBDEs), 23 non-PBDEs halogenated FRs (NPHFRs), 16 organophosphate esters (OPEs), 4 perfluorinated sulfonates (PFSAs), 13 perfluorinated carboxylic acids (PFCAs) and 5 emerging perfluoroalkyl acids (PFAAs) or precursors, were determined in 30 individual Caspian tern (listed as a threatened species in the U.S. State of Michigan) eggs collected in 2013 and 2014 from Michigan nesting sites on Two Tree Island (St, Mary's River), Charity Reef (Saginaw Bay) and Channel-Shelter Island (a Confined Disposal Facility (CDF) in Saginaw Bay). The same CEC suite was determined in 10 herring gull eggs on the Pipe Island Twins in the lower St. Mary's River. In tern eggs, the order of concentrations were ΣPFSA (mean: 793 ng/g wet weight (ww); range: 116–4690 ng/g ww) > ΣPFCAs (131; 30.4–506 ng/g ww) ≈ ΣPBDEs (86.7; 32.4–189 ng/g ww) » ΣNPHFRs (0.67; ND-4.3 ng/g ww) ≈ ΣOPEs (0.46; ND-2.89 ng/g ww). Compared to gull eggs collected from the same area, tern egg exposure contained significantly lower concentrations of ΣPBDE, but with up to 10 times greater mean concentrations of ΣPFSAs and ΣPFCAs. This study highlights the importance of consistent monitoring in eggs of different Great Lakes birds of PBDEs, perfluorooctane sulfonate (PFOS) and perfluoro-4-ethylcyclohexane sulfonate (PFEtCHxS) given that: 1) PBDE concentrations in all analyzed avian eggs exceeded or approached a concentration of 29 ng/g ww, which for birds is the current Canadian FEQG (Federal Environmental Quality Guideline); 2) ΣPBDE concentrations were comparable to lowest observed effect concentration (LOEC) values reported in the literature; 3) PFOS concentrations in Caspian tern eggs were extremely high with many eggs across sites exceeding 1 ppm, and with the greatest being up to 4.7 ppm; and 4) PFEtCHxS, a potentially persistent and bioaccumulative substance, showed a detection frequency of 100% in 40 of the analyzed eggs.

The Arctic tern (Sterna paradisaea) is a well-known polar seabird which breeds around the circumpolar Arctic, and which undertakes the longest known annual migration of any organism. Despite its familiarity, there is little information on its breeding biology in the High Arctic, an important baseline against which future studies of climate change impacts on northern wildlife can be compared. We studied the breeding biology of Arctic terns in the Canadian High Arctic during five field seasons, and compared this to breeding biology of terns from more southern parts of its range. Because our field site was beside a productive polynya, we expected that reproductive metrics for terns nesting there would be relatively high. However, mean clutch size (1.7 eggs), mean egg size (40.2 mm × 29.0 mm), mean nest initiation dates (6 July) were similar to Arctic terns breeding elsewhere. With our data, we could not assess the independent effects of predation pressure, poor weather or low food supplies, but two years with low tern reproduction were also years with low adult body mass and low clutch size (indicating poor food supplies), as well as low hatching success and high nest abandonment (possibly due to high predation pressure).

Based on information obtained from publications, online material and experienced birdwatchers we describe changes in the breeding avifauna of Israel between 2003 and 2016. We provide details on nine species that were found breeding in Israel during this period for the first time (Common Shelduck, Great Cormorant, Black-winged Kite, Caspian Tern, White-cheeked Tern, Common Wood Pigeon, Black Bush Robin, Basra Reed Warbler, Chiffchaff); two species that were found breeding in Israel after they were not documented breeding for more than 50 years (Great Crested Grebe, Pallid Scops Owl), one species that significantly extended its breeding range in Israel (Striated Heron), and two exotic species that have recently established populations in Israel (Monk Parakeet, Vinous-breasted Starling). This brings the number of bird species breeding in Israel in 2016 to 220. We also report here that out of six new breeding species reported in 2003, three species established breeding populations in Israel, while the other s...

Cartier Island and the surrounding reef is an isolated Australian Territory situated in the Timor Sea. Little is known about the avifauna of the reef system and the adjacent waters. Here we summarise all known ornithological records from the Island and detail the results of twice-annual bird surveys conducted within the Cartier Island Commonwealth Marine Reserve between 2010 and 2014. By the conclusion of the surveys, a total of 34 bird species had been recorded within the Reserve. The Crested Tern Thalasseus bergii was shown to breed on the Island in small numbers. Several additional species of seabird and small numbers of shorebirds are regular visitors. Most other species occur as occasional visitors or vagrants.

Pulau Ling is a small rocky island located to the south of Pulau Redang, forming with other southeast small islands, the Redang Archipelago, in the state of Terengganu, Malaysia. The island was highlighted in the early 1950s as an important seabird site, although little was then known on the status of seabirds on the island. Field visits were made between May 2015 and September 2015 to assess the importance of this small island to seabird species. Four tern species were identified: two of them, black-naped tern Sterna sumatrana and bridled tern Onychoprion anaethetus, were found to breed there, while the other two species, great crested tern Thalasseus bergii and roseate tern Sterna dougallii were found to use the island as a stopover site without any evidence of breeding. Furthermore, the Pacific Eastern Reef egret Egretta sacra (the black morph), was also found to breed on the island. Other species encountered included white-bellied sea eagle Haliaeetus leucogaster (recorded once in June 2015, soaring over the island). These preliminary data show the importance of such small rocky outcrops for tropical breeding and migrating seabirds, where food availability and lack of disturbance may be the two main drivers for diversity and survival.

The assessment of the relevance of forage fsh in seabird diet and how diferent species partition food resources is fundamental to understand predator–prey relationships. We assessed the importance of forage fsh in the diet of Royal (Thalasseus maximus maximus) and Cayenne (T. sandvicensis eurygnathus) terns and their partitioning of food resources during the early and late chick stages of 2013 and 2014 at a colony in Argentina. Direct observation of prey deliveries during chick provisioning showed that diet composition of Royal and Cayenne terns comprised at least 16 and 9 prey species, respectively. In both tern species, Argentine Anchovy (Engraulis anchoita) and fve species of silversides (Odontesthes spp.) were the main prey fed to chicks (over 90% contribution, anchovy and silversides pooled). Both tern species fed their chicks with similar prey species, but Royal terns delivered, in general, larger prey than Cayenne terns. Based on carbon and nitrogen isotopic values from chick whole blood samples, Bayesian mixing models showed that anchovies and silversides contributed similarly to the diet of both tern species’ chicks. Both conventional and stable isotope methods showed a high overlap in their trophic niches. Prey sizes delivered to chicks were larger in the late chick stage and the second study season. Wind speed did not have a signifcant efect on the frequency of the diferent prey species and sizes delivered to chicks by both tern species. As anchovies and silversides are fshery targets, tern trophic requirements should be considered when planning future fsheries development and management. Fil: Marinao, Cristian Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Centro para el Estudio de Sistemas Marinos; Argentina Fil: Suárez, Nicolás. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Centro para el Estudio de Sistemas Marinos; Argentina Fil: Gatto, Alejandro Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Centro para el Estudio de Sistemas Marinos; Argentina Fil: Yorio, Pablo Martin. Wildlife Conservation Society; Estados Unidos

Simple Summary Feral cats living completely independently of people are, unequivocally, agents of wildlife decline, which is linked to the local extinction of numerous bird, mammal and reptile species worldwide. However, evidence of the impact of pet and semi-feral (stray) cats on wildlife is somewhat limited, possibly due to the rapidity with which predation events occur. This study highlights the impact of a semi-feral cat on a threatened seabird colony of Australian Fairy Terns, Sternula nereis nereis, in Mandurah, south-western Australia. Evidence for significant predator-induced mortality, the alteration of the natural behavior of nesting birds in response to a persistent predator, and the complete reproductive failure of 111 nests—due, largely, to predation by a single, desexed, semi-feral cat—is presented. Trap-neuter-release was proposed as a humane response to tackle cat overpopulation but it fails to address the recurrent depredations on native wildlife that occur post-release. This case-study demonstrates that desexed, free-roaming cats remain a significant threat to wildlife and can lead to swift population declines and the local extirpation of native species. Abstract Domestic cats have a cosmopolitan distribution, commonly residing in urban, suburban and peri-urban environments that are also critical for biodiversity conservation. This study describes the impact of a desexed, free-roaming cat on the behavior of a threatened coastal seabird, the Australian Fairy Tern, Sternula nereis nereis, in Mandurah, south-western Australia. Wildlife cameras and direct observations of cat incursions into the tern colony at night, decapitated carcasses of adult terns, dead, injured or missing tern chicks, and cat tracks and scats around the colony provided strong evidence of cat predation, which led to an initial change in nesting behavior and, ultimately, colony abandonment and the reproductive failure of 111 nests. The death of six breeding terns from the population was a considerable loss for this threatened species and had the potential to limit population growth. This study highlights the significant negative impacts of free-roaming cats on wildlife and the need for monitoring and controlling cats at sites managed for species conservation. It also provides strong evidence against the practice of trap-neuter-release programs and demonstrates that desexed cats can continue to negatively impact wildlife post-release directly through predation, but also indirectly through fundamental changes in prey behavior and a reduction in parental care.

Some seabird species have shown to be carriers of human pathogenic bacteria, given their occurrence in contaminated coastal areas. This in turn may pose a health risk to humans and become a possible factor in the spread of infectious diseases. In this scenario, we studied whether potential human pathogenic bacteria of genera Escherichia, Vibrio, and Staphylococcus can be traced in the Heermann’s Gull and the Elegant Tern, two seabirds from Isla Rasa, Gulf of California. To this end, freshly deposited fecal droppings from both seabirds were collected and evaluated through several methods (standard bacterial methods, multiplex PCR, 16S rRNA sequencing, and matrix-assisted laser desorption ionization time-of-flight mass spectrophotometry). We identified Escherichia coli isolates, however, no evidence of pathogenicity was found. The analysis of the 16S rRNA sequences allowed the identification of isolates related to Vibrio alginolyticus and Vibrio parahaemolyticus, both previously reported as human pathogens. Also, analysis of 16S rRNA and matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) leads to the identification of isolates related to Staphylococcus saprophyticus, Staphylococcus sciuri, and Staphylococcus aureus, also reported as human pathogens. However, the identified bacteria do not represent any of the species or strains that most importantly affect humans. This study represents the first approach to the identification of pathogenic microorganisms in seabirds nesting in the central region of the Gulf of California; however, it was limited to only two species of seabirds and a few microorganisms. Therefore, monitoring and surveillance work like this should be continued and expanded to other species.

Contaminants in the marine environment are widespread, but ship-based sampling routines are much narrower. We evaluated the utility of seabirds, highly-mobile marine predators, as broad samplers of contaminants throughout three tropical ocean regions. Our aim was to fill a knowledge gap in the distributions of, and processes that contribute to, tropical marine contaminants; and explore how species-specific foraging ecologies could inform or bias our understanding of contaminant distributions. Mercury and persistent organic pollutant (POPs) concentrations were measured in adults of five seabird species from four colonies in the central Pacific (Laysan and Tern Islands, Hawaii; Palmyra Atoll) and the eastern Caribbean (Barbuda). Blood-based total mercury (THg) and 89 POPs were measured in two seabird families: surface-foraging frigatebirds (Fregata spp.) and plunge-diving boobies (Sula spp.). Overall, largescale contaminant differences between colonies were more informative of contaminant distributions than inter-specific foraging ecology. Model selection results indicated that proximity to human populations was the best predictor of THg and POPs. Regional differences in contaminants were distinct: Barbudan Magnificent Frigatebirds had more compounds (n=52/89 POP detected) and higher concentrations (geometric mean THg=0.97μgg-1; mean ΣPOP53=26.6ngmL-1) than the remote colonies (34-42/89 POP detected; range of THg geometric means=0.33-0.93μgg-1; range of mean ΣPOP53:7.3-17.0ngmL-1) and had the most recently-synthesized POPs. Moderate differences in foraging ecologies were somewhat informative of inter-specific differences in contaminant types and concentrations between nearshore and offshore foragers. Across species, contaminant concentrations were higher in frigatebirds (THg=0.87μgg-1; ΣPOP53=17.5ngmL-1) compared to boobies (THg=0.48μgg-1; ΣPOP53=9.8). Ocean currents and contaminants' physiochemical properties provided additional insight into the scales of spatial and temporal contaminant exposure. Seabirds are excellent, broad samplers with which we can understand contaminant distributions in the marine environment. This is especially important for tropical remote regions that are under-sampled.

Contamination of Arctic marine environments continues to be a concern for wildlife managers. Because the Arctic is a sink for the long-range transport of persistent organic pollutants (POPs), many studies have detected high concentrations of POPs in various Arctic birds. In this study from high Arctic Canada, we show that male Arctic terns (Sterna paradisaea), which migrate from the Antarctic to the Arctic annually to breed, decline in concentrations of many hepatic POPs through the breeding season. This suggests that local Arctic food webs are less contaminated than regions where terns fed during or migration, despite that the terns appear to feed at a higher trophic level near their colony.

Summary 1.Dietary studies give vital insights into foraging behaviour, with implications for understanding changing environmental conditions and the anthropogenic impacts on natural resources. Traditional diet sampling methods may be invasive or subject to biases, so developing non-invasive and unbiased methods applicable to a diversity of species is essential. 2.We used digital photography to investigate the diet fed to chicks of a prey-carrying seabird, and compared our approach (photo-sampling) to a traditional method (regurgitations) for the greater crested tern Thalasseus bergii. 3.Over three breeding seasons, we identified >24,000 prey items of at least 48 different species, more than doubling the known diversity of prey taken by this population of terns. We present a method to estimate the length of the main prey species (anchovy Engraulis encrasicolus) from photographs, with an accuracy < 1 mm and precision ~0.5 mm. Compared to regurgitations at two colonies, photo-sampling produced similar estimates of prey composition and size, at a faster species accumulation rate. The prey compositions collected by two researchers photo-sampling concurrently were also similar. 4.Photo-sampling offers a non-invasive tool to accurately and efficiently investigate the diet composition and prey size of prey-carrying birds. It reduces biases associated with observer-based studies and is simple to use. This methodology provides a novel tool to aid conservation and management decision-making in light of the growing need to assess environmental and anthropogenic change in natural ecosystems. This article is protected by copyright. All rights reserved.

Common white terns Gygis alba lay a single egg balanced on rocks or branches and consequently are at risk of low nesting success. A novel technique of hollowing out coconut husks and providing artificial nest sites was developed on Cousine Island, Seychelles. Our study aimed to critically assess whether common white tern nesting success differed between artificial and natural nest sites. For natural nest sites, nesting success and the stage of nest failure were also compared between seasons, nest heights, and tree species. Finally, we compared results from our study to those of a study conducted 10 years ago on the same island. Nesting success differed significantly between artificial nests and natural nests, with the success of artificial nests nearly double that of natural nests. Hatching success was similar for artificial and natural nests (65% and 52% respectively), suggesting coconut husks do not reduce egg losses, but rather provide secure perches for young chicks. Most natural nest failures occurred during the egg phase (70%), followed by the youngest chick phase (21%). Of the eggs that hatched in natural nests, 61% fledged successfully. Tree species and season significantly influenced nesting success for natural nests and nest height varied significantly between tree species. Higher nesting success was observed during the mixed seasonal period (50%) followed by the cooler, windier and drier South-East Monsoon season (33%). The hotter and more humid North-West Monsoon period had the lowest nesting success (20%). Comparisons of nesting success at natural and artificial nest sites with the earlier study did not differ significantly, despite a smaller population of common white terns being present on the island at that stage. Our results support the use of artificial nest sites to improve nesting success for this species and serve as a model for similar species currently under threat.Keywords: common white tern, Gygis alba, nest failure, nest success, Seychelles

The Lesser Crested Tern (Thalasseus bengalensis) is a ground-nesting seabird that breeds only on subtropical and tropical islands from northern Africa to northern Australia. Despite their wide distribution, few studies have been conducted on the breeding ecology of this species. On Jana Island, Saudi Arabia, which is northeast of the Saudi Arabia mainland, the midday ground temperature may reach 60 °C during the summer. In this study, two cameras were used to record the incubation behavior of Lesser Crested Terns to evaluate their coping ability in this extremely hot environment. The behavioral mechanism that the seabirds used to maintain optimal egg temperatures was also evaluated. The results show that Lesser Crested Terns attend their eggs continuously during a 24-hr period without leaving the nests, except when a disturbance occurs. This behavior prevents the eggs from reaching lethal temperatures. In addition, position of the sun influenced the incubation behavior. Most incubating Lesser Cr...

Sable Island is the most isolated seabird colony site in eastern Canada and the United States, offering a unique opportunity to study the population dynamics of terns and gulls in an area removed from human activities. Sable Island likely supported tens of thousands of terns prior to 1900, but the population declined during the first half of the 20th century, coinciding with colonization by breeding gulls. An island-wide census of terns and gulls was conducted in 2012 and 2013, and those results were compared with surveys conducted over the previous 45 years to assess changes in population abundance and distribution. The current island-wide population of Common (Sterna hirundo) and Arctic (S. paradisaea) terns was approximately 6,500 and 4,200 combined breeding pairs in 2012 and 2013, respectively, down from about 9,000 pairs estimated in 2008/2009, but higher than all estimates between 1970 and 2006. Population growth of these tern species has been concentrated at two large colonies, each with over 2,000 breeding pairs, whereas the number of small colonies on the island has been in decline since 1998. Fewer than six pairs of Roseate Terns (S. dougallii) have nested on Sable Island since 1993, down from counts of more than 100 individuals in the 1970s. Estimates of breeding pairs ranged from 744 to 951 Herring Gulls (Larus argentatus) and 398 to 472 Great Black-backed Gulls (L. marinus) during 2012 and 2013. A survey of gulls documented 33 to 50% fewer Herring Gulls and 23% fewer Great Black-backed Gulls than in 1970. Sable Island's tern and gull populations have fluctuated asynchronously over the past 100 years, and may be returning to a previous ecosystem state when gulls were absent and terns were abundant, but mechanisms underlying these trends are unknown.

Swains Island is an uninhabited 210 ha former copra plantation 360 km North of American Samoa. The island, dominated with coconut palm (Cocos nucifera), was last surveyed in 1976. The goal of this 17–26 September 2012 survey was to identify the bird species present, and document relative abundance, distribution, and breeding activity across the island. Two shoreline surveys recorded a seabird community dominated by Black Noddy (Anous minutus), White Tern (Gygis alba), and Brown Noddy (Anous stolidus), while the reef flat community was dominated by Pacific Golden Plover (Pluvialis fulva) and Wandering Tattler (Tringa incana). Inland surveys revealed four roosting or breeding species, including Black Noddy, White Tern, Brown Noddy, and Red-footed Booby (Sula sula). Seabird densities were highest in the northwest section of the island, furthest from former settlements. Although feral pigs (Sus scrofa) were recently eradicated, feral cats (Felis cattus) remain present, and Pacific rats (Rattus exulan...

Kosrae, the easternmost high island of Micronesia, is a 110 km2 volcanic island rising up to 630 m above sea level. It is seldom visited by birders and ornithologists because it is small, isolated, and lacks any previously recognized extant endemic bird species. We review the history of research on the island's avifauna and summarize the status of each species, including documentation for six new species: Northern Pintail (Anas acuta), Gray Plover (Pluvialis squatarola), Common Snipe (Gallinago gallinago), Bristle-thighed Curlew (Numenius tahitiensis), Red-necked Stint (Calidris ruficollis), and Whiskered Tern (Chlidonias hybrida). We discuss previously undescribed vocalizations of endemic taxa and provide online reference to recordings. We also present supporting evidence for the recognition of two taxa as full biological species: Kosrae Fruit Dove (Ptilinopus hernsheimi; formerly part of the P. porphyraceus complex) and Kosrae White-eye (Zosterops cinereus, as a split from Gray-brown White-eye...

Social attraction techniques have been demonstrated effective in restoring seabird breeding colonies, especially colonies of terns (Subfamily: Sterninae). The Chinese crested tern (Thalasseus bernsteini) is a critically endangered seabird with a global population of about 100 breeding adults and a breeding range restricted to the East China Sea and the Yellow Sea. In order to restore a breeding colony of Chinese crested terns in an archipelago where a former colony had been abandoned, social attraction (decoys and audio playback systems) was deployed on a small, uninhabited island with no history of seabird nesting. The objective was to establish a breeding colony of greater crested terns (T. bergii), a closely-related common species, in the hope that Chinese crested terns would follow. Thousands of greater crested terns and at least 19 Chinese crested terns colonized the island during the first breeding season after deployment of social attraction. After three years of successful breeding, the colony was abruptly abandoned early in the fourth breeding season because of invasive king rat snakes (Elaphe carinata), which consumed all tern eggs. Following removal of all snakes from the colony, terns resumed nesting the subsequent year. Recovery of this critically endangered seabird depends on repeating this process at multiple islands. Careful planning, in conjunction with habitat management, close colony monitoring, and deployment of social attraction, can establish a conservation network of suitable, secure colony sites where most breeding adults can reproduce successfully. This approach can be used to restore a variety of declining seabird species along the Chinese coastline.

Alimentary exposure is the main factor determining halogenated organic compound pollution of wildlife, with birds’ eggs recognised as bioindicators of these contaminants and often used as a non-invasive monitoring tool. Comparisons of bird species from two aquatic environments, namely a marine coastal area (Gdansk Bay) and an inland reservoir (Włocławek Dam on the Vistula River), indicated significant differences in egg contamination. Herring gull eggs from Włocławek Dam had high concentrations of highly chlorinated dioxin (i.e. octachlorodibenzodioxin, which accounted for 37% of all polychlorinated dibenzo-p-dioxins and polychlorinated dibenzo furans, PCDD/Fs). In contrast, eggs from terns feeding along the coastal area of the Southern Baltic contained high concentrations of lowly chlorinated furans (i.e. pentachlorodibezofuran, which accounted for 46 and 45% of all PCDD/Fs in eggs from the sandwich tern and common tern respectively). The congener patterns in terns’ eggs were similar to those reported previously for Baltic fish. Polychlorinated biphenyl congener 180 had the highest concentrations among the mono-ortho chlorinated biphenyls, whereas concentrations of non-dioxin-like chlorinated biphenyls were 10-fold higher than those of the other congeners analysed, but the congener pattern in eggs from both species (sandwich and common tern) was similar to that reported in other studies. Among the hexabromocyclododecane (HBCD) isomers, α-HBCD dominated in all eggs analysed (accounting for >97% of all HBCDs). The total HBCD concentration in gulls’ eggs from the inland reservoir was approximately half that in eggs from the common and sandwich terns (mean±s.d. 47.33±33.22v. 97.98±59.69 and 104.00±63.66ngg–1 lipid weight respectively).

Diet is the major route of exposure to environmental contaminants in biota and, after penetration into an organism, xenobiotics continue to accumulate in the body. In birds the egg-laying process acts as a transfer mechanism for the accumulated pollutants and results in the burdening of the next generation at an early stage of development. This transfer has a strong influence on developmental disorders and even breeding success. With this in mind polybrominated diphenyl ethers (PBDE), polychlorinated dibenzo-p-dioxins and polychlorinated dibenzo furans (PCDD/Fs), as well as polychlorinated biphenyls (PCBs), were analyzed in the eggs of aquatic birds from different habitats and with different diet preferences. The highest concentration of PBDE was noted in gull eggs (198.31 ng g−1 dw.) and the lowest in tern eggs (sandwich tern: 76.96 ng g−1 dw.; common tern: 113.73 ng g−1 dw). Deca-BDE was detected only in herring gull eggs from the Wloclawek reservoir. PCDDF/s were found in the eggs of terns from the southern coast of the Baltic Sea and gulls from an inland reservoir (dam) on the River Vistula close to the town of Wloclawek. The highest toxicity (birds Toxic Equivalent Factor) was found in the eggs of terns (sandwich tern – 93.97 pg g−1 dw., common tern – 68.35 pg g−1 dw.), and this was found to be several times higher than in herring gull eggs (18.80 pg g−1 dw.). Non-dioxin like PCBs were ten times higher than other analyzed PCB congeners, but the congener pattern was similar to other studies.

1.Understanding drivers of population change is critical for effective species conservation. In the northeast Atlantic Ocean, recent changes amongst seabird communities are linked to human and climate change impacts on food webs. Many species have declined severely, with food shortages, and increased predation reducing productivity. Arctic skua Stercorarius parasiticus, a kleptoparasite of other seabirds, is one such species. 2.The aim of the study was to determine relative effects of bottom‐up and top‐down pressures on Arctic skuas across multiple colonies in a rapidly declining national population. 3.Long‐term monitoring data were used to quantify changes in population size and productivity of Arctic skuas, their hosts (black‐legged kittiwake Rissa tridactyla, common guillemot Uria aalge, Atlantic puffin Fratercula arctica, Arctic tern Sterna paradisaea) and an apex predator (great skua Stercorarius skua) over 24 years (1992–2015) in Scotland. We used digital mapping and statistical models to determine relative effects of bottom‐up (host productivity) and top‐down (great skua density) pressures on Arctic skuas across 33 colonies, and assess variation between three colony types classified by host abundance. 4.Arctic skuas declined by 81% and their hosts by 42%–92%, whereas at most colonies great skuas increased. Annual productivity declined in Arctic skuas and their hosts, and reduced Arctic skua breeding success was a driver of the species’ population decline. Arctic skua productivity was positively associated with annual breeding success of hosts and negatively with great skua density. Intercolony variation suggested Arctic skua trends and productivity were most sensitive to top‐down pressures at smaller colonies of host species where great skuas had increased most, whereas bottom‐up pressures dominated at large colonies of host species. 5.Scotland's Arctic skua population is declining rapidly, with bottom‐up and top‐down pressures simultaneously reducing breeding success to unsustainably low levels. Marine food web alterations, strongly influenced by fisheries management and climate change, are driving the decline, and this study demonstrates severe vulnerability of seabirds to rapid change in human‐modified ecosystems. Potential but untested conservation solutions for Arctic skuas include marine protected areas, supplementary feeding within colonies and management of great skuas.

Synergistic effect refers to simultaneous actions of separate factors which have a greater total effect than the sum of the individual factor effects. However, there has been a limited knowledge on how synergistic effects occur and individual roles of different drivers are not often considered. Therefore, it becomes quite challenging to manage multiple threatening processes simultaneously in order to mitigate biodiversity loss. In this regard, our hypothesis is, if the traits actually play different roles in the synergistic interaction, conservation efforts could be made more effectively. To understand the synergistic effect and test our hypothesis, we examined the processes associated with the endangerment of critically endangered Chinese Crested Tern ( Thalasseus bernsteini ), whose total population number was estimated no more than 50. Through monitoring of breeding colonies and investigations into causative factors, combined with other data on human activities, we found that widespread human harvest of seabird eggs and increasing frequency of typhoons are the major factors that threatened the Chinese Crested Tern. Furthermore, 28 percent of breeding failures were due to the synergistic effects in which egg harvest-induced renestings suffered the higher frequent typhoons. In such combined interactions, the egg harvest has clearly served as a proximal factor for the population decline, and the superimposition of enhanced typhoon activity further accelerated the species toward imminent extinction. Our findings suggest that species endangerment, on one hand, should be treated as a synergistic process, while conservation efforts, on the other hand, should focus principally on combatting the threat that triggers synergistic effects.

Saunders's Tern ( Sternula saundersi) is a small ground-nesting seabird which breeds in the coasts and islands of Africa and Asia bordering the northern Indian Ocean. Despite having a wide distribution, little information is available on the breeding biology of this species. This study was carried out on Farasan Islands, Saudi Arabia, to document some aspects of the breeding biology of this species using a small trail camera. Such camera systems can reveal the incubation routine of this species in such a harsh environment. The midday ground temperature in March may reach up to 50 °C, while the midnight ground temperature may only reach 20 °C, thus leaving the eggs unattended even for few minutes, especially during the hottest and coldest parts of the day, may cause nest failure. This huge variation in ground temperatures between day and night gave us an excellent opportunity to test the behavioural mechanism used by the parents for maintaining the optimal egg temperature so as to protect their eggs. We found that nest attendance increases when the temperatures deviated from the optimal egg temperature, and nests were incubated for more than 90% of the time during the hottest and coldest parts of the day to prevent eggs from harmful temperatures.

Six species of terns, which breed on the Arabian Peninsula, were examined for head chewing lice of the genus Saemundssonia in four different islands around the coasts of Saudi Arabia, both in the Red Sea and in the Arabian Gulf. Four louse species were collected: Saemundssonia laticaudata, Saemundssonia melanocephalus, Saemundssonia meridiana and Saemundssonia sternae, of which three are recorded for the first time from this region. Also, we record three new host-louse associations for the world-Saemundssonia laticaudata and Saemundssonia sternae from white-cheeked terns and Saemundssonia melanocephalus from Saunders's terns-including a host-switch event of Saemundssonia laticaudata on white-cheeked terns in the Karan Island population. Gene bank data for the COI gene from seven species of Saemundssonia that infest marine birds were used to propose evolutionary trees using two different statistical methods: maximum parsimony (MP) and neighbour joining (NJ). The result indicated that the tree which was produced by NJ is likely to be more accurate as it appeared more compatible with hosts' phylogeny. The trees indicate relationships between tern Saemundssonia and congeneric species from other marine birds, especially from gulls. An ANOVA was also conducted to test the mean parasite load for each tern species studied, and results indicate that there is a relation between louse loads and colonization behaviour of the hosts. Data from lice examined and illustrations of lice and their hosts are also included.

We estimated annual apparent survival rates, as well as local recruitment rates in different age groups and for different breeding status in the common tern Sterna hirundo using mark-recapture analysis on a long-term individual-based dataset from a breeding colony in Germany. Strong inter-annual variability in survival rates became apparent, especially in prospectors. Local recruitment also varied strongly between years and age groups. To explain these fluctuations, we linked survival and recruitment estimates to several environmental covariates expected to be limiting during the wintering period and migration, including the global climate indices of North Atlantic Oscillation and Southern Oscillation, fish abundance indices, and marine primary productivity in the West African wintering area. Contrary to expectations, global indices did not seem to be linked strongly to vital rates. Results showed that primary productivity had the strongest effect on annual survival, especially in young and inexperienced individuals. Primary productivity in the wintering area was also strongly associated with the probability of recruitment in the following breeding season, indicating that conditions during winter can have carry-over effects on the life cycle of individuals.

Birds were surveyed in the Yamuna Nagar District, Haryana, India and the threat categories of the species observed were determined with the IUCN Red List. A total of 185 species belonging to 46 families were observed. Families Accipitridae, Passeridae, Corvidae and Scolopacidae dominated the list. There were 13 species with various IUCN Red List categories. One Critically Endangered species, the Red-headed Vulture Sarcogyps calvus, and two Endangered species Black-bellied Tern Sterna acuticauda and Egyptian Vulture Neophron percnopterus were observed. A prerequisite for all the measures focussed on management and conservation of species is that the status and population trends of the target species must be known, and future work should be in this direction.

Migration patterns are believed to greatly influence concentrations of contaminants in birds due to accumulation in spatially and temporally distinct ecosystems. Two species of fish-eating birds, the Double-crested Cormorant (Phalacrocorax auritus) and the Caspian Tern (Hydroprogne caspia) breeding in Lake Ontario were chosen to measure the impact of overwintering location on mercury concentrations ([Hg]). We characterized (1) overwintering areas using stable isotopes of hydrogen (δ(2)H) and band recoveries, and (2) overwintering habitats by combining information from stable isotopes of sulfur (δ(34)S), carbon (δ(13)C), nitrogen (δ(15)N), and δ(2)H in feathers grown during the winter. Overall, overwintering location had a significant effect on [Hg]. Both species showed high [Hg] in (13)C-rich habitats. In situ production of Hg (e.g., through sulfate reducing bacteria in sediments) and allochthonous import could explain high [Hg] in birds visiting (13)C-rich habitats. Higher [Hg] were found in birds with high δ(2)H, suggesting that Hg is more bioavailable in southern overwintering locations. Hotspot maps informed that higher [Hg] in birds were found at the limit of their southeastern overwintering range. Mercury concentrations in winter feathers were positively related to predicted spatial pattern of [Hg] in fish using the National Descriptive Model of Mercury in Fish (NDMMF) based on bird spatial assignment (using δ(2)H). This study indicates that the overwintering location greatly influences [Hg].

As top predators that feed on a wide range of prey items, gull diets may serve as important biological indicators of regional prey availability and changes in marine ecosystems. We studied the diets of herring gulls Larus argentatus and great black-backed gulls L. marinus on Sable Island, Nova Scotia, Canada, a remote colony which has shown high levels of contaminants in herring gull eggs and which has experienced significant ecological and anthropogenic change in its surrounding marine region over the past 40 yr. Analysis of regurgitated pellets suggested that current gull diets have proportionally less offshore prey (e.g. fish) and terns and tern eggs, and proportionally more molluscs, rock crabs Cancer borealis, and seal Halichoerus grypus car- rion than diets sampled 40 yr ago. The composition of recent diets observed from pellet analysis is supported by stable isotope mixing models of carbon (δ 13 C) and nitrogen (δ 15 N), which revealed that great black-backed gulls had high proportions of seals and crab in their diets, whereas her- ring gulls had high proportions of crab, sand lance Ammodytes sp., and terrestrial invertebrates. Isotopic analyses also identified dietary variability through seasonal, age-specific and body condi- tion relationships for each species. Biometricisotope relationships showed that larger great black-backed gulls fed at higher trophic levels, and that higher trophic level foraging in herring gulls was associated with better body condition. Collectively, these results indicate dietary parti- tioning within this community of sympatrically nesting gulls, and broad-scale dietary shifts since the early 1970s.

We investigated colony size, productivity, and limiting factors for five piscivorous waterbird species nesting at 18 locations on the Columbia Plateau (Washington) during 2004–2010 with emphasis on species with a history of salmonid (Oncorhynchus spp.) depredation. Numbers of nesting Caspian terns (Hydroprogne caspia) and double-crested cormorants (Phalacrocorax auritus) were stable at about 700–1,000 breeding pairs at five colonies and about 1,200–1,500 breeding pairs at four colonies, respectively. Numbers of American white pelicans (Pelecanus erythrorhynchos) increased at Badger Island, the sole breeding colony for the species on the Columbia Plateau, from about 900 individuals in 2007 to over 2,000 individuals in 2010. Overall numbers of breeding California gulls (Larus californicus) and ring-billed gulls (L. delawarensis) declined during the study, mostly because of the abandonment of a large colony in the mid-Columbia River. Three gull colonies below the confluence of the Snake and Columbia rivers increased substantially, however. Factors that may limit colony size and productivity for piscivorous waterbirds nesting on the Columbia Plateau included availability of suitable nesting habitat, interspecific competition for nest sites, predation, gull kleptoparasitism, food availability, and human disturbance. Based on observed population trends alone, there is little reason to project increased impacts to juvenile salmonid survival from tern and cormorant populations. Additional monitoring and evaluation may be warranted to assess future impacts of the growing Badger Island American white pelican colony and those gull colonies located near mainstem dams or associated with Caspian tern colonies where kleptoparasitism is common.

Between 2006 and 2013, we salvaged and necropsied 362 seabird specimens from Tern Island, French Frigate Shoals, Northwestern Hawaiian Islands. Plastic ingestion occurred in 11 of the 16 species sampled (68.75%), representing four orders, seven families, and five foraging guilds: four plunge-divers, two albatrosses, two nocturnal-foraging petrels, two tuna-birds, and one frigatebird. Moreover, we documented the first instance of ingestion in a previously unstudied species: the Brown Booby. Plastic prevalence (percent occurrence) ranged from 0% to 100%, with no significant differences across foraging guilds. However, occurrence was significantly higher in chicks versus adult conspecifics in the Black-footed Albatross, one of the three species where multiple age classes were sampled. While seabirds ingested a variety of plastic (foam, line, sheets), fragments were the most common and numerous type. In albatrosses and storm-petrels, the plastic occurrence in the two stomach chambers (the proventriculus and the ventriculus) was not significantly different.

Sheringham Shoal Offshore Wind Farm (OWF), comprised of 88 3.6 MW turbines, was built within foraging range of Sandwich Tern Thalasseus sandvicensis breeding at a European designated site. Boat-based surveys (n = 43) were used to investigate changes in tern abundance within the site and within 0–2 and 2–4 km buffer areas before and throughout the construction of the OWF, over a study period between 2009 and 2012. Visual tracking of individual birds (n = 840) was also undertaken to document any changes in behaviour. This study is amongst the few to detail the response of a breeding seabird to the construction of an OWF. Navigational buoys in the 0–2 km buffer were used extensively by resting and socialising birds, especially early in the breeding season. Visual tracking illustrated avoidance of areas of construction activity and birds surprisingly kept their distance from installed monopiles. Avoidance was strengthened during turbine assembly, with around 30% fewer birds entering the wind farm, relative to the pre-construction baseline. Flight lines of birds that entered the site were generally along the centre of rows between turbines. A focus on transit flight meant that feeding activity was lower in the site than the buffer areas. As the site remained permeable to terns flying to and from foraging grounds further offshore, the overall abundance within the site was not significantly reduced. Although a number of the responses observed were unforeseen by Environmental Impact Assessment, the overall conclusion of only minor adverse effects was upheld. Analysis of further data from the operational site is now planned.

Regular surveys of waterbird colonies are needed to identify changes in abundance and distribution. Consistent surveys have been maintained in some regions, but one area where updated surveys were needed was southern Manitoba, where Lakes Winnipeg, Winnipegosis and Manitoba had not been jointly surveyed since 1979. In mid-June, 2012, an aerial survey of the region was conducted using digital photography to estimate abundance of six colonial waterbird species that are regular breeders on these lakes. Breeding by at least one of the six species was confirmed at 131 locations. Double-crested Cormorant (Phalacrocorax auritus) was the most abundant breeder (43,388 pairs, 47 colonies), followed by Ring-billed Gull (Larus delawarensis, 41,819 pairs, 67 colonies), American White Pelican (Pelecanus erythrorhynchos, 12,680 pairs, 20 colonies), Common Tern (Sterna hirundo, 7,950 pairs, 31 colonies), Herring Gull (L. argentatus, 4,013 pairs, 90 colonies) and Caspian Tern (Hydroprogne caspia, 3,207 pairs, 14...