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Approximately 60% of the 45 species of terns (Sternae) have an unusual form of wing molt in which a variable number of inner primaries and outer secondaries are replaced two or three times in a single year-a process that has been called 'repeated molt.' Although several hypotheses have been proposed for the maintenance of repeated molt, few data exist regarding potential selective forces that may have favored the evolution of this molt strategy, and there are no explanations for the high degree of interspecific variation in the extent of repeated molt. Preliminary investigations indicated that large terns tended to have less repeated molt than small terns and that the presence of repeated molt appeared to be associated with migratory behavior. We examined these initial findings by combining data from the literature, from examinations of museum specimens, and from a recent molecular phylogeny of the terns to perform phylogenetic-comparative tests. First, we used independent contrasts to verify that the association between large terns and less repeated molt was significant and not a result of shared ancestry. Second, we used tests for binary character association to evaluate the apparent link between repeated molt and migratory behavior. The results of these tests, along with reconstructions of ancestral states, led to a potential explanation for the origin of repeated molt, in which a tropical, sedentary ancestor gave rise to several lineages that spread to temperate areas and adopted a migratory life history. With this shift to a more seasonal regime came shortened breeding periods and perhaps more time for molt, which could have led to modifications of the ancestral molting strategy and the origin of repeated molt.

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.

Three families of probe-foraging birds, Scolopacidae (sandpipers and snipes), Apterygidae (kiwi), and Threskiornithidae (ibises, including spoonbills) have independently evolved long, narrow bills containing clusters of vibration-sensitive mechanoreceptors (Herbst corpuscles) within pits in the bill-tip. These 'bill-tip organs' allow birds to detect buried or submerged prey via substrate-borne vibrations and/or interstitial pressure gradients. Shorebirds, kiwi and ibises are only distantly related, with the phylogenetic divide between kiwi and the other two taxa being particularly deep. We compared the bill-tip structure and associated somatosensory regions in the brains of kiwi and shorebirds to understand the degree of convergence of these systems between the two taxa. For comparison, we also included data from other taxa including waterfowl (Anatidae) and parrots (Psittaculidae and Cacatuidae), non-apterygid ratites, and other probe-foraging and non probe-foraging birds including non-scolopacid shorebirds (Charadriidae, Haematopodidae, Recurvirostridae and Sternidae). We show that the bill-tip organ structure was broadly similar between the Apterygidae and Scolopacidae, however some inter-specific variation was found in the number, shape and orientation of sensory pits between the two groups. Kiwi, scolopacid shorebirds, waterfowl and parrots all shared hypertrophy or near-hypertrophy of the principal sensory trigeminal nucleus. Hypertrophy of the nucleus basorostralis, however, occurred only in waterfowl, kiwi, three of the scolopacid species examined and a species of oystercatcher (Charadriiformes: Haematopodidae). Hypertrophy of the principal sensory trigeminal nucleus in kiwi, Scolopacidae, and other tactile specialists appears to have co-evolved alongside bill-tip specializations, whereas hypertrophy of nucleus basorostralis may be influenced to a greater extent by other sensory inputs. We suggest that similarities between kiwi and scolopacid bill-tip organs and associated somatosensory brain regions are likely a result of similar ecological selective pressures, with inter-specific variations reflecting finer-scale niche differentiation.

Due to the ability of birds to travel long distances in the air, the potential feeding area of each individual is much larger than that of typical terrestrial animals. This makes birds a convenient indicator of environmental lead (Pb) pollution over large areas, in particular areas of inland and coastal waters. The aim of this study was to assess the concentrations of Pb in various organs of water birds from a variety of locations. The focus was on ducks, geese and swans ( Anatidae ); herons and egrets ( Ardeidae ); terns ( Sternidae ); and gulls ( Laridae ). This article describes the level of lead in the most commonly studied tissue types: feathers, bones and the liver. The study also presents data concerning the concentration of lead in the eggs of water birds. The highest levels of lead pollution can be observed in China and Korea, related to their high level of industrialization. In Iran too, environmental lead pollution is high, likely due to the developed petrochemical industry. Lead pollution in Japan, as well as in Western European countries (Spain, France, Italy), seems to be much lower than in China, India or Iran. Nevertheless, the level of pollution in Europe is higher than satisfactory, despite the introduction of a number of bans related to, for example, the use of leaded petrol or lead-containing paints. Finally, the USA and Canada appear to be the areas with the lowest lead pollution, possibly due to their low population densities.

Although sleep is necessary for maintaining physiological and cognitive function in birds, nocturnal sleep behavior has yet to be documented for terns. Nocturnal sleep behavior and vigilance of incubating Common Terns (Sterna hirundo) were explored at two colonies, Gull Island (Ontario, Canada) for six years, and Little Island (New York, USA) throughout one breeding season, using ∼1-min interval, time-lapse images from infrared trail cameras. Behavioral posture and vigilance (eye[s] open) of visible study birds were recorded from the images to determine if these differed between the two colonies. Terns utilized two sleeping postures, Back Sleep and Front Sleep, nearly identical to those used by gulls. Differences in the proportion of time spent sleeping between the two colonies were surprisingly large. Terns at Gull Island spent 75% less time in Back Sleep (deep-sleep posture, 7% of the night) than those at Little Island, and 64% of night with their eyes open (vs. <20% at Little Island). Differences between the study sites that may have caused this disparity include predation risk, colony size, vegetation cover and the presence of other nesting waterbirds. Apparent, long-term sleep deprivation at Gull Island may have physiological impacts. Further research is needed to establish causes and effects of differences in nocturnal sleep behavior in Common Terns.

The provision of artificial nest structures is used in the conservation of a broad range of bird groups including raptors, owls, ducks, passerines and seabirds, with varying degrees of success. Artificial nestboxes have been provided to increase the density and breeding success of Roseate Tern pairs at colonies in north‐west Europe and the eastern seaboard of the USA and Canada, but their effect on breeding productivity has never been comprehensively quantified. Using 15 years of monitoring data, based on daily nest monitoring visits, we carried out a comparative analysis of the breeding performance of Roseate Tern pairs utilizing artificial nestboxes with those in open nests, on Rockabill Island (Ireland), to evaluate the effectiveness of nestbox installation as a conservation measure. Nestboxes were used ahead of open sites early in the season, likely by the experienced breeding pairs. Hatching success and fledging success were higher for pairs in nestboxes compared with those in open nest sites. Earlier clutches were more successful than later ones, independent of the effects of nest site type. The results of this study show definitively that Roseate Terns nesting in nestboxes perform better than those using open nest sites at their largest European colony and that nestboxes are chosen ahead of other sites, likely by the experienced breeding pairs. We recommend the continued and expanded use of nestboxes to help maximize the densities and breeding performance of the Roseate Tern. A Roseate Tern using a nestbox on Rockabill Island. We show, using comparative analyses of long‐term breeding data, that nests in nestboxes are more productive than open nests. More eggs successfully survive to hatch and more nestlings survive to fledge in nestboxes.

Gull-billed Terns (Gelochelidon nilotica) have historically demonstrated variability in nest-site selection and reproductive success throughout their breeding range. However, few studies have investigated the breeding parameters of Gull-billed Tern populations on barrier islands in the northern Gulf of Mexico, USA. The main objective of this study was to investigate annual variability of breeding population size, hatching success, and causes of nest failure during eight breeding seasons (2009–2016). Annual variation was observed in colony sizes (Range = 1–68 nests), colony locations (among five islands), and hatching success (0–93%). Mean hatching success was 56% and flooding was the main cause of failure, accounting for 64% of all failed nests. Additionally, nest site habitat characteristics were compared between successful and unsuccessful Gull-billed Tern nests. Nest substrate composition differed between successful and failed nests, and successful nests were also associated with higher elevation, greater distance from the high tide line, and less vegetative cover. There was considerable variation in Gull-billed Tern breeding population size and hatching success, which may be attributable to the dynamic nature of barrier island habitats. Long-term monitoring is required to better understand the breeding dynamics of Gull-billed Terns, but conservation efforts should consider maintaining island habitats that are protected from flooding and have adequate nesting substrate, minimal vegetation, and limited disturbance from humans and predators.

We isolate and characterise 16 polymorphic microsatellite loci for the super-abundant, pan-tropical sooty tern ( Onychoprion fuscatus ), facilitating population genetic studies. In 70 samples from two breeding colonies, the total number of alleles per locus ranged between 5 and 21, observed heterozygosity ranged from 0.143 to 0.942, while estimated null allele frequency varied from −0.131 to 0.273. Polymerase chain reaction (PCR) conditions were optimised across loci, enabling multiplexing and rapid multilocus genotyping. These 16 loci will be useful for future studies of genetic diversity and population structure, and can be used as a proxy through which to assess ecosystem function and change. We additionally test cross-species amplification in the brown ( Anous stolidus ) and lesser ( A. tenuirostris ) noddies, illustrating a use of these microsatellites in other related Sternidae species.

We examined how seabirds might be used to study marine environmental variables, which necessitates knowing location and the value of the variable to be studied. Five systems can potentially be used for determination of location: VHF (Very High Frequency) telemetry, PTT (Platform Terminal Transmitters) telemetry, GLS (Global Location Service) geolocation methods, dead reckoning and GPS (Global Positioning System), each with its own advantages with respect to accuracy, potential number of fixes and size. Temperature and light were used to illustrate potential difficulties in recording environmental variables. Systems currently used on seabirds for measurement of temperature respond slowly to environmental changes; thus, they may not measure sea surface temperature adequately when contact periods with water bodies are too short. Light can be easily measured for light extinction studies, but sensor orientation plays a large role in determining recorded values. Both problems can be corrected. The foraging behaviour of seabirds was also examined in order to identify those features which would be useful for determination of marine environmental variables at a variety of spatial and temporal scales. Area coverage by birds is highly dependent on breeding phase and tends to be concentrated in areas where prey acquisition is particularly enhanced. The identification of these sites may be of particular interest to marine biologists. ‘Plungers’ and ‘divers’ are potentially most useful for assessment of variables deeper within the water column, with some divers spending up to 90% of their time sub-surface. Few seabirds exploit the water column deeper than 20 m, although some divers regularly exceed 50 m (primarily penguins and auks), while 2 species dive in excess of 300 m. The wide-ranging behaviour of seabirds coupled, in many instances, with their substantial body size makes them potentially excellent carriers of sophisticated environmental measuring technology; however, the ethical question of how much the well-being of birds can, and should, be compromised by such an approach needs to be carefully considered.

Each year between 1989 and 2008, I monitored Common Tern colonies in the lagoon of Venice (Italy). This population nests only on salt marsh islets, which are subjected to flooding during high tides. The number of breeding pairs decreased significantly from 832 to 109, with an average rate of decrease of −10.1%. Overall, 188 colonies were found, ranging from two to 583 pairs; median colony size was 57 pairs, and it decreased significantly. The mean turnover rate was high at 41.5%, and it ranged each year between 7.7% and 60%. The observed trends could be attributed to the increase in mean sea level that occurred over the last 20 years (0.5 cm/yr). In the May–June period, the number of days with high tides leading to a complete flooding of the breeding site increased. Between 1989 and 1998 there was on average 4.4 days with floodings. This increased to 8.4 days between 1999 and 2008. Therefore, sea level rise could be a major contributor to declining Common Tern populations in the lagoon of Venice.