Roseate Terns Sterna Dougallii Research Articles

A case study of the 2023 highly pathogenic avian influenza (HPAI) outbreak in tern (Sternidae) colonies on the east coast of the Republic of Ireland

ABSTRACT Capsule:HPAI H5N1 had a significant impact on breeding Common Terns Sterna hirundo, Arctic Terns Sterna paradisaea and Roseate Terns Sterna dougallii on the east coast of the Republic of Ireland (ROI) in 2023, with a lesser impact on Sandwich Terns Thalasseus sandvicensis and only two cases among Little Terns Sternula albifrons. Aims: To document the outbreak of HPAI H5N1 in the tern colonies on the east coast of ROI during the 2023 breeding season. Methods:Precautions were taken from the start of the breeding season, including personal protective equipment (PPE) and safe operating procedures. Regular meetings were held between BirdWatch Ireland and the National Parks and Wildlife Service (NPWS) to respond to the emerging situation. Once HPAI was confirmed in a colony, all ringing and nest visits were stopped. Carcass removal was carried out at all affected colonies and most carcasses were incinerated. Results: Common Terns suffered the highest mortality across all colonies in 2023, with smaller but notable numbers of dead Roseate Terns and Arctic Terns, but very few Sandwich Terns and only two Little Tern deaths were attributed to HPAI. Conclusion: Regular meetings between relevant organizations were invaluable in preparing for outbreaks and ensuring an adaptive approach as the situation changed over time and between colonies. There was no way of knowing if the actions taken were effective, as the pattern of virus spread between species and sites remains poorly understood. Future clarity over the role of various state agencies and other relevant bodies in responding to HPAI in wild birds, greater sharing of real-time information, and pre-arranged agreements to ensure rapid testing and disposal of carcasses, would be useful to ensure an effective response to future outbreaks.

NOTES ON THE ROSEATE TERN Sterna dougallii BREEDING IN KARIMUNJAWA ISLANDS, JAVA, INDONESIA

Roseate Tern Sterna dougallii is a rare to uncommon resident and migrant species in Greater Sundas, with only a handful records in Java. On 24 May 2021, a nest containing a single egg of the species was found in Karang Ketel islet, Karimunjawa Islands and constitute the first breeding record of Roseate Tern in the area, filling the breeding information gap of the species in Java for about 80 years since it first reported. Follow up surveys after the findings carried out for three consecutive years from May 2021-June 2023, reveals the species regularly breeding in three locations, i.e., Karang Ketel islet, Karang Kapal islet, and Krakal Besar I. Breeding recorded from May to August, with only small colony of 2-20 birds present.

Common Terns Sterna hirundo and Roseate Terns Sterna dougallii frequently rest on the sea surface in winter quarters and during migration

ABSTRACT Capsule Common Terns Sterna hirundo and Roseate Terns S. dougallii rarely rest on the sea surface during the breeding season but frequently do so in winter and on migration. Aims To investigate the behaviour of Common and Roseate Terns throughout the annual cycle using immersion sensors. Methods We analyzed data from immersion sensors attached to 11 Common Terns and 6 Roseate Terns that bred in the northeastern USA and wintered either on the north or east coasts of South America, to investigate temporal patterns of resting on saltwater throughout the annual cycle. Results Both species of tern rarely contacted salt water during the breeding season, except when bathing or plunge-diving, but in winter they spent several hours each day resting on the sea surface. This resting was most frequent around midday and least frequent in early mornings and late afternoons. Night-time immersion varied widely among individuals but terns wintering in eastern Brazil were less likely to spend the night on the sea surface than those wintering on the north coast of South America. We suggest that this reflected the availability of dry-land roosting sites. Conclusion Our results are consistent with and extend studies from Europe, confirming that although Common and Roseate Terns spend very little time resting on the sea surface in the breeding season, this behaviour is frequent during migration and wintering periods.

An investigation into factors contributing to mortality of young terns at a managed colony

Terns are a highly migratory group of seabirds that are found worldwide. In Ireland, there are five species of commonly breeding tern: Little Tern Sternula albifrons, Roseate Tern Sterna dougallii, Arctic Tern S. paradisaea, Common Tern S. hirundo and Sandwich Tern S. sandvicensis. Prior work has demonstrated that whilst many Irish tern species, including Common and Roseate Terns, are increasing in abundance, the productivity of these species can be low. Multiple factors may influence the ability of adult terns to successfully raise chicks, including food availability, provisioning rates, colony density, dependence effects, and/or disease. Here, we investigated factors contributing to the mortality of young terns from Rockabill Island in the Republic of Ireland, which supports the largest breeding population of Roseate Terns in Europe. To better understand the factors contributing to the deaths of young birds, we analysed the macroscopic and microscopic characteristics of necropsies of 60 young Common, Arctic and Roseate Terns. Of the carcasses that we examined, 41 showed congested blood circulation in the lungs and head simultaneously, and of the remaining 19 birds, only five presented a clear cause of death. Here, we outline descriptions of these carcasses in addition to recommendations of further investigations that might help to confirm the causal factors leading to young tern mortality.

Upwelling systems in the migration ecology of Roseate Terns (Sterna dougallii) breeding in northwest Europe

For migratory seabirds, staging and wintering areas may be important targets for conservation. Declines of Roseate Tern Sterna dougallii populations have led to conservation initiatives at breeding sites on both sides of the North Atlantic. However, these could be compromised by environmental conditions in non‐breeding areas. The migratory ecology of Roseate Terns is poorly known and we used light‐level biologgers (geolocators) to identify the migratory routes, staging and wintering areas of Roseate Terns from two European colonies. Most birds wintered off the Ghanaian coast in the Gulf of Guinea, but some wintered further west off Sierra Leone and Liberia, or changed locations during the winter. In these areas, cold‐water upwellings of the Guinea Current Large Marine Ecosystem (GCLME) may provide vital foraging resources. Geolocations in combination with temperature measurements and satellite sea‐surface temperature data show that cold‐water upwellings of the Canary Current Large Marine Ecosystem (CCLME) were important areas for migratory staging, particularly on the return migration which was slower than the outward journey. These results emphasize the importance of productive cold‐water upwellings in the migratory ecology of Roseate Terns. The GCLME and CCLME are under threat from over‐exploitation, pollution and climate change; effective conservation of these environments will be important to secure the long‐term future of these and other seabirds.

Roseate Terns Sterna dougallii on the southeast coast of South Africa: information on moult and migratory status

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.

Offshore surprises: new at-sea bird records for Suriname (2013\u20132015)

Bird observations were collected from various types of survey vessels in Suriname’s territorial waters between 2013 and 2015. Dedicated, effort-related surveys were carried out from geophysical seismic survey vessels within an area located 80–110 km offshore (in 2013) and 165–290 km (in 2015). Opportunistic observations were recorded during fisheries surveys on a shrimp trawler operating along the 30 m depth contour, approximately 40–60 km offshore (in 2014). In total, 10 bird (sub-)species were observed during these surveys that previously were not recorded for Suriname, including Manx Shearwater Puffinus puffinus, Ruff Calidris pugnax, South Polar Skua Stercorarius maccormicki, Long-tailed Jaeger Stercorarius longicaudus, Sandwich Tern Thalasseus sandvicensis (ssp. acuflavidus), Roseate Tern Sterna dougallii, Bridled Tern Onychoprion anaethetus, Black Noddy Anous minutus, Scarlet Tanager Piranga olivacea and Black-and-white Warbler Mniotilta varia. In addition, Lesser Black-backed Gull Larus fuscus and Bulwer’s Petrel Bulweria bulwerii were photographed for the first time in Suriname. A Sooty Shearwater Ardenna grisea was recorded just outside the Exclusive Economic Zone (EEZ), and therefore does not count as a new country record. This paper contributes to a better understanding of the avifauna frequenting the waters off Suriname, which historically has been poorly studied. Most of the species reported here are migratory. The timing of our sightings therefore also helps in a better understanding of their at-sea distribution and migration patterns.

Prebreeding survival of Roseate Terns Sterna dougallii varies with sex, hatching order and hatching date

Unequal sex ratios can reduce the productivity of animal populations and are especially prevalent among endangered species. A cohort of 333 Roseate Tern Sterna dougallii chicks at a site where the adult sex ratio was skewed towards females was sexed at hatching and followed through fledging and return to the breeding area, and subsequently during adulthood. The entire regional metapopulation was sampled for returning birds. Prebreeding survival (from fledging to age 3 years) was lower in males than in females, but only among B‐chicks (second in hatching order). Prebreeding survival also declined with hatching date. The proportion of females in this cohort increased from 54.6% at hatching to 56.2% at fledging and to an estimated 58.0% among survivors at age 3 years. This was more than sufficient to explain the degree of skew in the sex ratio of the adult population, but changes in this degree of skew during the study period make it difficult to identify the influence of a single cohort of recruits. Many studies of prebreeding survival in other bird species have identified effects of sex, hatching order or hatching date, but no previous study has tested for effects of all three factors simultaneously.

Non-breeding season movements of six North American Roseate Terns Sterna dougallii tracked with geolocators

Little is known of the endangered and declining western North Atlantic population of the Roseate Tern Sterna dougallii outside the breeding season, when most mortality probably occurs. We used geolocators to track Roseate Terns in 2007 and 2009 and retrieved six units with useful data. In the post-breeding period in July-August, all six birds staged around Cape Cod, close to the breeding site. They started southward migration from 28 August to 14 September and flew directly across the western North Atlantic Ocean to staging areas around Puerto Rico and the Dominican Republic. We identified five major areas and four minor areas in the West Indies and along the north and east coasts of South America where birds stopped over for 2-24 d during southward and northward migrations. Birds arrived at (Northern Hemisphere) wintering areas from Guyana/Suriname on the north coast of South America to eastern Brazil between 3 October and 2 November. They left wintering areas from 7-23 April and arrived back at the breeding area from 5-30 May. Although this study is based on data for only six birds, it identifies several stopover and wintering areas that should receive priority for future studies and potential conservation measures. Geolocators did not impair Roseate Terns' ability to raise young in the year the devices were attached, but lower than expected rates of return suggest that the geolocators reduced survival, and most of the birds that returned had lost body-mass and did not breed in the year of return.

First documented record of the Roseate Tern Sterna dougallii Montagu, 1813 (Aves: Sternidae) in southeast Brazil

We report the first record of Sterna dougallii Montagu, 1813 on the southeastern Brazilian coast. During monthly bird surveys in the northern Rio de Janeiro State, on January 2012 we recovered a tern banded in Massachusetts, USA. The present record stretches the S. dougallii southernmost geographic distribution in Brazil (Bahia state) by about 600 km. It is difficult to evaluate this species’ regional status due to the absence of continuous sampling efforts.

Tail length and sexual selection in a monogamous, monomorphic species, the Roseate Tern Sterna dougallii

Both male and female Roseate Terns (Sterna dougallii) have unusually long outer tail feathers, and males tend to have longer tails than females. We examined whether these tail streamers may have evolved as a result of sexual selection, using data from a 15-year study at Bird Island, Massachusetts, USA. Data on tail length were analyzed for 2,515 terns, of which 745 were of known sex. Tail length was positively correlated with predictors of reproductive success, such as laying date, body mass, and age, and thus can act as an indicator of mate quality. The increase in mean tail length with age appeared to result from a combination of growth in relatively young terns and differential survival among older terns. The mean duration of pair bonds was short at 1.73 years. A female-biased sex ratio is present in this population, and we demonstrated that short-tailed females are not preferred mates: females paired to males had longer tails than those in female–female pairs or other multi-female associations. In male–female pairs, tail lengths of mates were correlated, but this may have resulted in part from the correlation in ages. These observations are consistent with the hypothesis that tail streamers are used by both sexes in mate choice. In contrast to our results for tail length, tail symmetry was not significantly related to indices of individual quality and was not significantly correlated between mates.

The influence of early age at breeding on reproductive parameters of tropical Roseate Terns

At Aride Island, Seychelles, western Indian Ocean, over a period of five years (2002–2006), early-age (2–5 years) Roseate Terns Sterna dougallii nested in more concealed sites than older-age (6–7 years) birds, possibly because of a relatively lower competitive ability. Fledging success and breeding productivity were higher for older birds, but clutch size, laying date and egg volume were most influenced by marine productivity (the concentration of chlorophyll a in adjacent seas, which was assumed to reflect feeding conditions) or by an interaction between marine productivity and age. Older birds bred earlier in years when food availability was greater, but younger birds did not do so. Annual variations in environmental conditions should be taken into account when examining the effect of age on the reproductive parameters of tropical Roseate Terns.

Annual Recapture and Survival Rates of Two Non-Breeding Adult Populations of Roseate Terns Sterna dougallii Captured on the Great Barrier Reef, Australia, and Estimates of their Population Sizes

Abstract Capture-recapture data from two disparate breeding populations of Roseate Terns (Sterna dougallii) captured together as non-breeding individuals from 2002 to 2007 in the southern Great Barrier Reef, Australia were analyzed for both survival rate and recapture rate. The average annual survival rate for the two populations in the study area was estimated at 0.850. There is strong evidence that the average annual survival rate for the birds from the Asian population (S. d. bangsi) (0.901) is higher than that of the other population of unknown breeding origin (0.819). There was large variability in survival in both populations among years, but the average survival rate of 0.85 is similar to estimates for the same species in North America. The Cormack-Jolly-Seber models used in program MARK to estimate survival rates also produced estimates of recapture probabilities and population sizes. These estimates of population size were 29,000 for S. d. bangsi and 8,300 for the ‘unknown’ group. The population ...

Consequences of a female‐biased sex‐ratio in a socially monogamous bird: female‐female pairs in the Roseate Tern Sterna dougallii

In the socially monogamous gulls and terns, female‐biased sex ratios are sometimes revealed by the occurrence of ‘supernormal clutches’, which are usually attended by female‐female pairs or other multi‐female associations. We studied these phenomena in the endangered Roseate Tern Sterna dougallii at Bird Island, USA, from 1970 to 1995. DNA‐techniques were used to sex breeding adults in 1992–94.Supernormal clutches (with three or four eggs) have comprised 1–7% of all Roseate Tern clutches at Bird Island since at least 1970, probably increasing in frequency since 1980. Supernormal clutches were spatially clustered; most were laid late in the peak period of nesting during each season. More than 80% of supernormal clutches and at least 7% of normal clutches were attended by multi‐female associations; most of these were female‐female pairs, with a few trios (male + two females, or three females) and one quartet (four females). More than half of the multi‐female associations attended normal clutches. Some female‐female pairs were maintained for up to five years. The age‐distribution of females mated to females did not differ significantly from that of females mated to males. Females mated together usually laid eggs synchronously (±2 days). Such females laid fewer eggs than females mated to males (means 1.20 versus 1.73), and had lower fertility and hatching success (about 46% versus 98%); they were less successful in raising young from eggs that did hatch (means 58% versus 73%), but this difference was not significant. Their overall breeding success was much lower (about 0.34 fledglings per female versus 1.35). The sex‐ratio of breeders was about 127 females to 100 males; about 20% of breeding females did not have male mates. Female Roseate Terns that do not obtain male mates appear to be of low phenotypic ‘quality’ ‐ based on late laying, small clutches and small eggs. Our data support the hypothesis that such females have a higher fitness if they mate with each other and raise a few young than if they do not breed at all.

A recovery plan for Roseate Terns in the East Atlantic: an international programme

SummaryIn 1987 an action plan for the recovery of the European populations of Roseate Tern Sterna dougallii was launched. Intervention on the breeding grounds has included the wardening of sites to prevent human disturbance, the provision of nest-boxes to discourage predation, patrolling and controlling to reduce predator presence, planting of Lavatera arborea to shelter nesting birds, and use of the media to establish local interest and commitment. Intervention in the wintering area has focused on Ghana and the reduction there of trapping pressure, through the “Save the Seashore Birds Project-Ghana”, which has involved site protection, legal reform, training, surveys and education programmes.

Books

Books reviewed in this article:BROMHALL, D. 1980. Devil birds: the life of the Swift.HAMMOND, N. & EVERETT, M. 1980. Birds of Britain and Europe.Hosking, E. & MacDonell, K. 1980. Eric Hosking's birdsHoward, R. & Moore, A. 1980. A complete checklist of the birds of the worldKovshar', A. F. 1979. (Songbirds in the subalpine zone of Tien‐shan.)Ly‐Tio‐Fane, M. 1978 (‘1976’). Pierre Sonnerat 1748–1814. An account of his life and workMoon, G. 1980. The birds around us: New Zealand birds, their habits and habitatsNisbet, I. C. T. 1980. Status and trends of the Roseate Tern Sterna dougallii in North America and the CaribbeanNorth‐Coombes, A. 1980 (‘1979’). The vindication of Frangois LeguatPemberton, J. E. 1980. The birdwatcher's yearbookSkutch, A. F. 1979. The imperative call: a naturalist's quest in temperate and tropical AmericaStonehouse, B. (ed.) 1978. Animal marking. Recognition marking of animals in researchSutcliffe, S. A. (ed.) 1979. Proceedings of the Second North American Conference on Common Loon Research and ManagementCarp, E. 1980. Dictionary of wetlands of international importance in the western PalearcticClark, R. J., Smith, D. G. & Kelso, L. H. 1978. Working bibliography of the owls of the worldCortes, J. E., Finlayson, J. C., Mosquera, M. A. & Garcia, E. F. J. 1980. The birds of GibraltarFalkus, H. 1980. Nature detectiveLincer, J. L., Clark, W. S. & LeFranc, M. N. 1979. Working bibliography of the Bald EagleLockley, R. M. 1980. Orielton: the human and natural history of a Welsh ManorPaine, A. J. R. Birds of prey in Suffolk 1973–78Phillips, W. W. A. 1978. Annotated checklist of the birds of Ceylon (Sri Lanka)

STATUS AND DISTRIBUTION OF THE ROSEATE TERN IN SOUTH AFRICA

Summary Randall, R. M. & Randall, B. M. 1980. Status and distribution of the Roseate Tern in South Africa. Ostrich 51:14-20. The Roseate Tern Sterna dougallii population in Algoa Bay is the largest, and now possibly the only breeding population in southern Africa. The two mainland breeding sites at Cape Recife and Kommetjie have been deserted, and in recent years the last remaining breeding site outside Algoa Bay may have been abandoned. Consequently the present estimate of between 70 and 80 breeding pairs in Algoa Bay may represent the entire southern African population. The decline in numbers from hundreds in 1937 is ascribed to human interference. Although the species is rare and endangered in southern Africa, it has a world wide distribution and is in no immediate danger of extinction.