Search

Breeding Common Terns (Sterna hirundo) have been studied extensively in North America and Europe, but little is known of the small, isolated populations south of the main continental ranges. We conducted a 69 year study of Common Terns in the Bermuda archipelago (in the western North Atlantic Ocean at ∼32°N) to document their phenology, distribution, numbers, and breeding biology. Common Terns arrive at Bermuda in March and start to nest about 10 April, 2–3 weeks earlier than any other population of the species studied to date. Unlike the colonially nesting mainland populations, Bermudian Common Terns nest singly or in very small groups on many small islets and artificial nest sites (n = 50 sites) scattered throughout the archipelago. The population included 15–36 pairs in the 1970s and 1980s, but declined by about 50% following each of 3 major hurricanes in 1987, 2003, and 2010, and is now critically endangered. Since the 2003 hurricane, the population has included many (up to 7) female–female pairs laying infertile eggs. In contrast, the mean clutch size of male–female pairs was 3.01, with mean productivity >2.2 fledglings/pair over the 69 year period, the highest values reported for the species anywhere in its range; in at least 10 cases, pairs raised 4 chicks to fledging. The Bermudian population of Common Terns is intensively managed but remains critically endangered, and its recent shift to nesting on small rafts and buoys about 3 m in diameter poses new challenges for management.

Declines in reproductive performance among older age classes have been reported in many bird and mammal species, and are commonly presented as demonstrating reproductive senescence. However, no declines in performance could be demonstrated in studies of several bird species. We measured reproductive performance in Common Terns (Sterna hirundo) of known age (2–28 yr) during a 19-yr period at a site in Buzzards Bay, Massachusetts, USA. We measured 6 components of reproductive performance and used generalized additive mixed models (GAMMs) in a Bayesian framework to analyze dependence of each measure on parental age, while controlling for variations among years and indices of individual quality. Four measures of performance improved (earlier laying date, higher values of clutch size, fledging success, and productivity) with age, most rapidly between ages 2 and 10 yr; egg mass and hatching success varied only slightly with age. No measure of performance showed reversals among the older age classes; fledging success and productivity continued to increase through at least age 22 yr. These findings are consistent with results from an earlier study of the same species. Continued increase in reproductive performance through the oldest age classes is not incompatible with “reproductive senescence” (decline in physiological or other functions required for successful reproduction) if either reproductive effort or efficiency continue to increase. Studies within our population have yielded no evidence for age-related increase in reproductive effort, but 3 studies have suggested that older Common Terns can raise chicks more successfully than younger birds without increasing reproductive effort, probably by more efficient foraging and chick provisioning. Our findings suggest that Common Terns offset reproductive senescence by continuing to improve efficiency through at least age 22 yr. Age-related changes in efficiency should be investigated in other species with similar life-history traits.LAY SUMMARYWe studied Common Terns (Sterna hirundo) at a breeding colony in Massachusetts from 1970 until 2003: we banded chicks when they hatched so that we could determine their age when they returned to breed at the same site in subsequent years.The terns' breeding success continued to improve with age throughout their lives and was still increasing among birds that were 22 years old.Common Terns continually improve their skills at finding fish and provisioning their chicks, even after 20 years of practice.

The endangered population of roseate terns ( Sterna dougallii ) in the Northwestern Atlantic Ocean consists of a network of large and small breeding colonies on islands. This type of fragmented population poses an exceptional opportunity to investigate dispersal, a mechanism that is fundamental in population dynamics and is crucial to understand the spatio-temporal and genetic structure of animal populations. Dispersal is difficult to study because it requires concurrent data compilation at multiple sites. Models of population dynamics in birds that focus on dispersal and include a large number of breeding sites are rare in literature. In this work, we propose a stochastic simulation model that captures the dispersal dynamics of this population of roseate terns. The colonization and decolonization (abandonment) of breeding colonies are modeled as discrete events that follow different dynamics than dispersal. We show that our model reproduces the properties of this population that have been observed in field data. We also analyzed the sensitivity of our model to alterations in different variables, and study the impact of these alterations in the model dynamics. Our results suggest that large colony population size exhibits a threshold sensitivity to adult survival, and that regional persistence is maintained by the larger populations.

Post-natal growth is an important life-history trait and can be a sensitive indicator of ecological stress. For over 50 years, monotonic (never-decreasing) growth has been viewed as the predominant trajectory of post-natal mass change in most animal species, notably among birds. However, prevailing analytical approaches and energetic constraints may limit detection of non-monotonic (or multiphasic), determinate growth patterns, such as mass recession in birds (weight loss prior to fledging, preceded by overshooting adult mass), which is currently believed to be restricted to few taxa. Energetic surplus and shortfall are widespread conditions that can directly influence the degree of mass overshooting and recession. Thus, we hypothesize that in many species, prevailing energetic constraints force mass change away from a fundamental non-monotonic trajectory to instead follow a monotonic curve. We observed highly non-monotonic, mass change trajectories (overshooting adult mass by up to almost 20%) among common tern Sterna hirundo chicks, a well-studied species long-established as growing monotonically. We quantified the prevalence and magnitude of non-monotonic mass change prior to fledging for 313 common tern chicks that successfully fledged from two discrete populations in multiple years. We used a new approach for analysing non-monotonic curves to examine differences in mass change trajectories between populations under contrasting abiotic (freshwater vs. saltwater) and biotic stresses (low rates of food provisioning). Some degree of mass recession occurred in 73% of all study chicks. Overshooting adult mass followed by extensive mass recession was most prevalent at our freshwater colony, being detected among 34-38% of chicks annually. Non-monotonic trajectories were less marked in populations experiencing ecological stress and among lower quality individuals. Chicks that were provisioned at higher rates were more likely to both overshoot adult mass and experience subsequent mass recession. Our results in common terns provide strong support for the hypothesis that non-monotonic trajectories are the fundamental pattern of mass change but are constrained to be monotonic under energetic shortfall. This justifies future tests of the generality of this hypothesis across a broad range of taxa. We also demonstrate a recent analytical tool that prevents routine fitting of monotonic curves without prior investigation of non-monotonic trends.

Little is known about sublethal effects on birds of low level exposure to oil. White blood cell parameters (total leukocyte counts and/or differentials) were measured in blood samples from Common Terns (Sterna hirundo; n = 71) exposed to low levels of oil from an oil spill in Buzzards Bay, Massachusetts, in 2003. Data from Common Terns (n = 16) sampled at the same site in a non-spill year were used for reference. Total leukocytes and lymphocytes were severely depressed when individuals were first sampled, 14–20 days after the spill, and returned to near to or above reference levels by day 39. Heterophils and heterophil/lymphocyte ratios were markedly elevated 14–20 days after the spill, and returned to below reference levels by day 39. These changes were closely parallel to changes in hematocrit in the same birds, but hematocrits were not correlated with white blood cell parameters, suggesting that mechanisms of action were different. The combination of immune suppression and anemia during the p...

In Bermuda, only three species of breeding seabirds survived four centuries of human activity, dating back to the settlement of the archipelago in 1609. This paper reports two consecutive years of nesting data on the Roseate Tern (Sterna dougallii), a historic breeder in Bermuda last recorded breeding in 1849. A pair was discovered incubating an egg on 7 July 2018 on Pearl Island, and a pair, plus one additional adult, returned to this islet to breed in 2019. Roseate Terns and nests were intensively monitored using offshore observations and video recordings. In 2018, the single egg hatched on 24 July and the chick fledged on 18 August (fledging period = 25 d). In 2019, we found a two-egg clutch on 4 June, which hatched on 15 and 17 June. The two chicks were flying by 13 July (fledging periods = 26-28 d). The breeding Roseate Terns in Bermuda are probably derived from the Caribbean/Bahamas population. The two-year nest-site fidelity of Roseate Terns, following absence for at least 140 years, suggests that this species is potentially reestablishing itself as a breeder in Bermuda. Future studies should determine the genetic origin of the birds, determine if the observed pairs are the same individuals using leg bands, record population growth, and compare the nesting biology of Bermudian Roseate Terns to that of the Bermudian Common Terns (Sterna hirundo).

Some previous studies of seabirds have suggested that birds renesting after earlier failures may lay smaller clutches and smaller eggs than the same birds in their first nestings. Common Terns (Sterna hirundo) were studied at a site where most first clutches and broods were destroyed by high seas from a hurricane on 22 June 1972. Most or all pairs renested 8-17 d (mean 11.2 d ± 2.1SD) after failure. Renesting pairs had lower clutch size than first-nesting pairs (means 2.11 vs 2.85), lighter eggs (20.08 vs 21.89 g for first eggs in the clutch) and lower productivity (≤ 1.24 vs 2.07 chicks raised to fledging). Two of 34 fledglings from renestings were subsequently encountered as breeders, versus 2 of 30 from surviving first nestings in 1972 and 5 of 73 from the same site in 1971. Hence, renesting contributed offspring to the next generation, although it must have entailed physiological, energetic and temporal costs to the parents.

Reproductive timing in many taxa plays a key role in determining breeding productivity , and is often sensitive to climatic conditions . Current climate change may alter the timing of breeding at different rates across trophic levels, potentially resulting in temporal mismatch between the resource requirements of predators and their prey . This is of particular concern for highertrophic-level organisms, whose longer generation times confer a lower rate of evolutionary rescue than primary producers or consumers. However, the disconnection between studies of ecological change in marine systems makes it difficult to detect general changes in the timing of reproduction5 . Here, we use a comprehensive meta-analysis of 209 phenological time series from 145 breeding populations to show that, on average, seabird populations worldwide have not adjusted their breeding seasons over time (−0.020 days yr−1 ) or in response to sea surface temperature (SST) (−0.272 days °C−1 ) between 1952 and 2015. However, marked between-year variation in timing observed in resident species and some Pelecaniformes and Suliformes (cormorants, gannets and boobies) may imply that timing, in some cases, is affected by unmeasured environmental conditions. This limited temperature-mediated plasticity of reproductive timing in seabirds potentially makes these top predators highly vulnerable to future mismatch with lower-trophic-level resources Fil: Keogan, Katharine. University of Edinburgh; Reino Unido Fil: Daunt, Francis. Centre for Ecology & Hydrology; Reino Unido Fil: Wanless, Sarah. Centre for Ecology & Hydrology; Reino Unido Fil: Phillips, Richard A.. British Antarctic Survey; Reino Unido Fil: Walling, Craig A.. University of Edinburgh; Reino Unido Fil: Agnew, Philippa. Oamaru Blue Penguin Colony; . Oamaru Blue Penguin Colony; Nueva Zelanda Fil: Ainley, David G.. HT Harvey and Associates; Estados Unidos Fil: Anker-Nilssen, Tycho. Norwegian Institute For Nature Research; Noruega Fil: Ballard, Grant. Point Blue Conservation Science; Estados Unidos Fil: Barrett, Robert T.. Uit The Arctic University Of Norway; Noruega Fil: Barton, Kerry J.. Landcare Research; Nueva Zelanda Fil: Bech, Claus. Norges Teknisk-naturvitenskapelige Universitet; Noruega Fil: Becker, Peter. Institut Fur Vogelforschung "vogelwarte Helgoland"; Alemania Fil: Berglund, Per-Arvid. University of Agricultural Sciences. Institute of Marine Research, Department of Aquatic Resources; Suecia Fil: Bollache, Loïc. Universite de Bourgogne; Francia Fil: Bond, Alexander L.. Memorial University Of Newfoundland; Canadá Fil: Bouwhuis, Sandra. Institut Fur Vogelforschung "vogelwarte Helgoland"; Alemania Fil: Bradley, Russell W.. Point Blue Conservation Science; Estados Unidos Fil: Burr, Zofia M.. The University Centre In Svalbard; Noruega Fil: Camphuysen, Kees. University of Utrecht; Países Bajos Fil: Catry, Paulo. Ispa - Instituto Universitário; Portugal Fil: Chiaradia, Andre. Monash University; Australia. Phillip Island Nature Park; Australia Fil: Christensen-Dalsgaard, Signe. Norwegian Institute for Nature Research; Noruega Fil: Cuthbert, Richard. Royal Society For The Protection Of Birds; Reino Unido Fil: Dehnhard, Nina. Universiteit Antwerp; Bélgica Fil: Descamps, Sébastien. Norwegian Polar Institute; Noruega Fil: Diamond, Tony. University Of New Brunswick; Canadá Fil: Divoky, George. Friends of Cooper Island; Estados Unidos Fil: Drummond, Hugh. Universidad Nacional Autónoma de México; México Fil: Dugger, Katie M.. United States Geological Survey; Estados Unidos Fil: Dunn, Michael J.. British Antarctic Survey; Reino Unido Fil: Emmerson, Louise. Australian Antarctic Division; Australia Fil: Erikstad, Kjell Einar. Norwegian Polar Institute; Noruega Fil: Fort, Jérôme. Université de la Rochelle; Francia Fil: Fraser, William. Polar Oceans Research Group; Estados Unidos Fil: Genovart, Meritxell. Consejo Superior de Investigaciones Cientificas. Instituto Mediterraneo de Estudios Avanzados; España Fil: Gilg, Olivier. Universite de Bourgogne; Francia. Groupe de Recherches En Ecologie Arctique; Fil: González-Solís, Jacob. Universidad de Barcelona; España Fil: Granadeiro, José Pedro. Universidade de Lisboa; Portugal Fil: Grémillet, David. University Of Cape Town; Sudáfrica Fil: Hansen, Jannik. University Aarhus; Dinamarca Fil: Hanssen, Sveinn A.. Norwegian Institute For Nature Research; Noruega Fil: Harris, Mike. Centre for Ecology & Hydrology; Reino Unido Fil: Hedd, April. Environment Canada; Canadá Fil: Hinke, Jefferson. National Oceanic And Atmospheric Administration; Estados Unidos Fil: Igual, José Manuel. Consejo Superior de Investigaciones Cientificas. Instituto Mediterraneo de Estudios Avanzados; España Fil: Jahncke, Jaime. Point Blue Conservation Science; Estados Unidos Fil: Jones, Ian. Memorial University Of Newfoundland; Canadá Fil: Kappes, Peter J.. Oregon Cooperative Fish And Wildlife Research Unit; Estados Unidos Fil: Lang, Johannes. Groupe de Recherche en Ecologie Arctique; Francia Fil: Langset, Magdalene. Norwegian Institute For Nature Research; Noruega Fil: Lescroël, Amélie. Géosciences Montpellier; Francia Fil: Lorentsen, Svein-Håkon. Norwegian Institute For Nature Research; Noruega Fil: Lyver, Phil O'B.. Landcare Research; Nueva Zelanda Fil: Mallory, Mark. Acadia University; Canadá Fil: Moe, Børge. Norwegian Institute For Nature Research; Noruega Fil: Montevecchi, William A.. Memorial University Of Newfoundland; Canadá Fil: Monticelli, David. University Of Coimbra, Marine And Environmental Sciences Center; Portugal Fil: Mostello, Carolyn. Massachusetts Division Of Fisheries And Wildlife; Estados Unidos Fil: Newell, Mark. Centre for Ecology & Hydrology; Reino Unido Fil: Nicholson, Lisa. Halfmoon Biosciences; Australia Fil: Nisbet, Ian. I. C. T. Nisbet & Company; Estados Unidos Fil: Olsson, Olof. Stockholms Universitet; Suecia Fil: Oro, Daniel. Consejo Superior de Investigaciones Cientificas. Instituto Mediterraneo de Estudios Avanzados; España Fil: Pattison, Vivian. Laskeek Bay Conservation Society; Canadá Fil: Poisbleau, Maud. Universiteit Antwerp; Bélgica Fil: Pyk, Tanya. Deakin University; Australia Fil: Quintana, Flavio Roberto. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Ramos, Jaime A.. University Of Coimbra, Marine And Environmental Sciences Center; Portugal Fil: Ramos, Raül. Universidad de Barcelona; España Fil: Reiertsen, Tone Kirstin. Norwegian Polar Institute; Noruega Fil: Rodríguez, Cristina. Universidad Nacional Autónoma de México; México Fil: Ryan, Peter. University Of Cape Town; Sudáfrica Fil: Sanz-Aguilar, Ana. Consejo Superior de Investigaciones Cientificas. Instituto Mediterraneo de Estudios Avanzados; España Fil: Schmidt, Niels M.. University Aarhus; Dinamarca Fil: Shannon, Paula. National Audubon Society Seabird Restoration Program; Estados Unidos Fil: Sittler, Benoit. Groupe de Recherche en Ecologie Arctique; Francia Fil: Southwell, Colin. Australian Antarctic Division; Australia Fil: Surman, Christopher. Halfmoon Biosciences; Australia Fil: Svagelj, Walter Sergio. Universidad Nacional de Mar del Plata; Argentina. 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 Fil: Trivelpiece, Wayne. Bolinas; Estados Unidos Fil: Warzybok, Pete. Point Blue Conservation Science; Estados Unidos Fil: Watanuki, Yutaka. Hokkaido University; Japón Fil: Weimerskirch, Henri. Centre National de la Recherche Scientifique; Francia Fil: Wilson, Peter R.. Landcare Research; Nueva Zelanda Fil: Wood, Andrew G.. British Antarctic Survey; Reino Unido Fil: Phillimore, Albert B.. University of Edinburgh; Reino Unido Fil: Lewis, Sue. University of Edinburgh; Reino Unido

Dispersal is increasingly recognized as a process of fundamental importance in population dynamics and other aspects of biology. Concurrently, interest in age-dependent effects on survival, including actuarial senescence, has increased, especially in studies of long-lived seabirds. Nevertheless, datasets necessary for studying dispersal and age-dependent effects are few, as these require simultaneous data collection at two or more sites over many years. We conducted a 22-year capture-mark-recapture study of Common Terns Sterna hirundo at three breeding colonies 10–26 km apart in Buzzards Bay, Massachusetts, USA. All birds in the study were of known age (range 2–28 years, median 7 years, n = 3290) and 77% were of known sex. Estimates of adult recapture, survival and breeding dispersal rates were obtained for all age-classes from 2 to 20 years. The model that acquired 100% of the QAICc (Akaike’s Information Criterion adjusted for small sample size and overdispersion) weight in our analysis included age-specificity in all parameters but no relationship with sex. Our study may be the first to demonstrate age-specificity in recapture, survival and breeding dispersal rates simultaneously, using a single model. Annual rates of breeding dispersal ranged from

Use of soft-metal (aluminum alloy) bands on gulls (Laridae) is known to result in high rates of band loss and, as a result, hard-metal (monel, incoloy, or stainless steel) bands are superior for most studies. However, the U.S. Bird Banding Laboratory (BBL) and the Canadian Wildlife Service Bird Banding Office continue to issue soft bands for use on gulls, and the BBL does not make specific recommendations about use of hard bands so many banders continue to use soft bands. For wholly marine species of gulls banded in North America since 1996, ∼20% have been banded with soft bands; the proportion of soft bands used on partially freshwater gulls was ∼70% up to 2009, but has since fallen to 40%. Using hierarchical Bayesian models in program MARK, we analyzed recovery data for three gull species and found that estimates of annual survival rates derived from soft bands (0.68–0.81) were lower than those derived from hard bands (0.85–0.96). Comparison of survival rates of Herring Gulls (Larus argentatus) in the Great Lakes basin and on the Atlantic coast provided no evidence that soft bands last longer in freshwater than saltwater. Band loss compromises many types of studies, including those assessing the possible effects of climate change. We recommend that use of soft bands on gulls be discontinued, and that banders be required to use hard bands on these species in the future. The same consideration applies to other long-lived species, including some waterfowl and all albatrosses, pelicans, cormorants, shearwaters, petrels, terns, shorebirds, and alcids. Use of hard bands should be based on expectations about a species’ longevity and evidence of band wear, rather than on whether or not it occurs in saltwater. RESUMEN Uso continuo de anillos blandos de metal en gaviotas de Norte America disminuye el valor de los datos de recapturas Es reconocido que el uso de anillos de metal blando (aleaciones de aluminio) en gaviotas (Laridae) resulta en tasas elevadas de perdida de los anillos. En consecuencia, anillos de metal duro (monel, incoloy o acero inoxidable) son de superior calidad para la mayoria de los estudios. Sin embargo, el Laboratorio de Anillamiento de Aves de Estados Unidos (U.S. Bird Banding Laboratory, BBL) y la Oficina de Anillamiento de Aves del Servicio Canadiense de Fauna Silvestre (Canadian Wildlife Service Bird Banding Office) continuan produciendo anillos de metal suave para su uso en gaviotas, y particularmente el BBL no hace recomendaciones especificas sobre el uso de anillos de metal duro. Por esta razon muchos anilladores continuan usando anillos blandos. Del total de individuos de gaviotas totalmente marinas de Norte America anillados desde 1996, ∼20% ha sido anillado usando anillos blandos; la proporcion de anillos blandos usados en gaviotas de agua dulce era del ∼70% hasta el 2009 pero ha disminuido desde entonces al 40%. Usando modelos Bayesianos jerarquicos en el programa MARK, analizamos datos de recapturas de tres especies de gaviotas y encontramos que las tasas anuales de supervivencia son menores cuando son estimadas a partir de datos de anillos blandos (0.68–0.81) que cuando son estimadas a partir de datos de anillos duros (0.85–0.96). Las comparaciones de las tasas de supervivencia en Larus argentatus entre la cuenca de los Grandes Lagos y en la costa Atlantica no sugieren que los anillos blandos tengan una duracion mayor en agua dulce que en agua salada. Recomendamos que se descontinue el uso de anillos blandos en gaviotas y que los anilladores utilicen anillos duros para estas especies en el futuro. La misma consideracion aplica para otras especies longevas, incluyendo algunas aves acuaticas y todos los albatroses, pelicanos, cormoranes, pardelas, petreles, gaviotines, aves playeras y alcidos. Las decision sobre el uso de anillos duros debe ser basada en la longevidad de las especies y la evidencia del desgaste del anillo mas bien que en la pregunta si la especie ocurre o no en agua salada.

Hematocrits were measured in Common Terns (Sterna hirundo) (n = 75) that were exposed to oil from a spill in Buzzards Bay, Massachusetts, USA, in 2003, and that laid eggs 17–39 days following the spill. Comparative data were obtained in three pre- and two post-spill years and from three unoiled reference sites. In non-spill years, annual means of hematocrit varied in parallel with breeding performance. Hematocrits were lower (mean 45.3, n = 75) and more variable in the oil spill year than in non-spill years, and 20% of birds sampled were anemic (hematocrit < 41.7). However, hematocrits were almost as low (mean 46.4, n = 44) in 2002, a year with naturally adverse conditions. In 2002, hematocrits and body-masses were depressed following two storms and recovered in parallel following the storms; hematocrits were positively correlated with body-mass and ambient temperature and negatively correlated with wind speed. In contrast, in 2003 hematocrits were negatively correlated with body-mass and temper...

Common and roseate terns are migratory piscivorous seabirds with major breeding colonies within feeding range of the polychlorinated biphenyl (PCB)-contaminated New Bedford Harbor (NBH, MA, USA) Superfund site. Our longitudinal study shows that before PCB discharges into NBH ceased (late 1970s), tern eggs had very high but variable PCB concentrations. However, egg concentrations of PCBs as well as DDE (1,1-bis(p-chlorophenyl)-2,2-dichloroethene), the degradation product of the ubiquitous global contaminant DDT (1,1,1-trichloro-2,2-bis(p-chlorophenyl) ethane), have since declined. Rate constants for temporal decline of PCB congeners in tern eggs varied inversely with log10KOW (n-octanol-water partition coefficient), shifting egg congener patterns away from those characterizing NBH sediment. To estimate the toxic effects on tern eggs of PCB dioxin-like congener (DLC) exposures, we extrapolated published laboratory data on common terns to roseate terns by characterizing genetic and functional similarities in species aryl hydrocarbon receptors (AHRs), which mediate DLC sensitivity. Our assessment of contaminant risks suggests that terns breeding near NBH were exposed historically to toxic levels of PCBs and DDE; however, acute effects on tern egg development have become less likely since the 1970s. Our approach demonstrates how comparative genetics at target loci can effectively increase the range of inference for chemical risk assessments from tested to untested and untestable species.

We used 22 yr of capture–mark–reencounter (CMR) data collected from 1988 to 2009 on about 12,500 birds at what went from three to five coastal colony sites in Massachusetts, New York, and Connecticut, United States, to examine spatial and temporal variation in breeding dispersal/fidelity rates of adult Roseate Terns (Sterna dougallii). At the start of our study, Roseate Terns nested at only one site (Bird Island) in Buzzards Bay, Massachusetts, but two more sites in this bay (Ram and Penikese Islands) were subsequently recolonized and became incorporated into our CMR metapopulation study. We examined four major hypotheses about factors we thought might influence colony-site fidelity and movement rates in the restructured system. We found some evidence that colony-site fidelity remained higher at long-established sites compared with newer ones and that breeding dispersal was more likely to occur among nearby sites than distant ones. Sustained predation at Falkner Island, Connecticut, did not result in a sustained drop in fidelity rates of breeders. Patterns of breeding dispersal differed substantially at the two restored sites. The fidelity of Roseate Terns at Bird dropped quickly after nearby Ram was recolonized in 1994, and fidelity rates for Ram soon approached those for Bird. After an oil spill in Buzzards Bay in April 2003, hazing (deliberate disturbance) of the terns at Ram prior to the start of egg-laying resulted in lowering of fidelity at this site, a decrease in immigration from Bird, and recolonization of Penikese by Roseate Terns. Annual fidelity rates at Penikese increased somewhat several years after the initial recolonization, but they remained much lower there than at all the other sites throughout the study period. The sustained high annual rates of emigration from Penikese resulted in the eventual failure of the restoration effort there, and in 2013, no Roseate Terns nested at this site.

— A difficulty in the study of monomorphic species is the inability of observers to visually distinguish females from males. Based on a sample of 745 known-sex birds nesting at Bird Island, MA, USA, a discriminant function analysis (DFA) was used to sex Roseate Terns (Sterna dougallii) of the Northwest Atlantic population using morphological measurements. DFA using only the total length of the head (including the bill) correctly identified the sex of approximately 86% of the terns, which increased to 88% if both members of a pair were measured. Including additional measurements increased these percentages slightly, to 87% and 90%, respectively. These levels of accuracy are generally higher than those reported for other species of terns. Because female-female pairs are frequent in this population, one cannot assume that the member of a pair with the larger head is a male, and additional discriminant functions were developed to help separate female-female from male-female pairs.

Summary 1. Nonlinear, parametric curve-fitting provides a framework for understanding diverse ecological and evolutionary trends (e.g. growth patterns and seasonal cycles). Currently, parametric curve-fitting requires ap rioriassumptions of curve trajectories, restricting their use for exploratory analyses. Furthermore, use of analytical techniques [nonlinear least-squares (NLS) and nonlinear mixedeffects models] for complex parametric curves requires efficient choice of starting parameters. 2. We illustrate the new R package FlexParamCurve that automates curve selection and provides tools to analyse nonmonotonic curve data in NLS and nonlinear mixed-effects models. Examples include empirical and simulated data sets for the growth of seabird chicks. 3. By automating curve selection and parameterization during curve-fitting, FlexParamCurve extends current possibilities for parametric analysis in ecological and evolutionary studies.

Stealing of provisioned food items by adult conspecifics (intraspecific kleptoparasitism or piracy) is common among birds, can reduce breeding success and may be one disadvantage of colonial breeding. Theft by chicks from neighbouring broods has rarely been quantified but may have similar reproductive consequences and the factors that influence it require further study. We took advantage of unusually diverse weather during the critical early stages of growth to elucidate the factors driving kleptoparasitic behavior of Common Tern Sterna hirundo chicks. Kleptoparasitism was restricted to misty days when large chicks were fed much smaller fish than on other days, inducing them to steal from neighbouring broods with young chicks. Our study indicates that kleptoparasitism by chicks could be a way to overcome shortfalls in parental provisioning, and may be a net cost of colonial breeding. Our results both provide evidence of a potential mechanism behind food-stealing by chicks and suggest hypotheses for future testing.

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.

Common Terns nesting at Bermuda are isolated by 1,000–4,000 km from other populations of the species around the North Atlantic Ocean. This population experienced a severe demographic bottleneck as a result of a hurricane in 2003 and was subsequently re-established by four males and four females. Using seven microsatellite loci, we compared the genetic diversity of the pre- and post-bottleneck populations, compared the genetic profile of the Bermuda population with those of other populations around the North Atlantic Ocean and mainland Europe, and assessed the potential contribution of immigration to genetic diversity. We found a loss of genetic diversity (number of alleles and heterozygosity) in the post-bottleneck Bermudian population (4.6–2.9 and 0.56–0.52, respectively). We also report significant differentiation among all sampled locations (global FST = 0.16) with no evidence for immigration into Bermuda. Common Terns from the Azores were genetically more similar to those from mainland North America than to those from Bermuda or mainland Europe. Our results suggest that the critically endangered population in Bermuda is genetically distinct and requires continued and enhanced conservation priority.

Social attraction, that is, mimicking of active and productive colonies via audio playback of calls of breeding conspecifics and the use of decoys, is commonly used to attract birds to newly established or restored breeding sites. However, little is known about the relative importance of aural versus visual cues for identify nesting areas. Such information is important for design and evaluation of management protocols. We studied the effectiveness of decoys (visual cues) and playbacks (audio cues) as methods for restoring a colony of common terns (Sterna hirundo) at Muskeget Island, Massachusetts, USA. We used a 2-year, crossover experiment with 3 treatment areas: audio and visual, audio only, and visual only. We reversed treatment areas in the second year to control for previous nesting area or substrate preference. In both years, nests were built 9–101 m downwind of loudspeakers. There was no overlap in areas used for nesting between years and no nests were built within decoy plots in either ye...

Ten geolocators (light-level data loggers) were attached to Common Terns (Sterna hirundo) at a breeding site in the northeastern USA in 2007 and 2008; six were retrieved (five with useful data) in 2008 and 2009. The birds wintered in four discrete areas on the north and east coasts of South America, from Guyana (6–7°N) to northeastern Argentina (36–42°S); three remained within restricted areas for most or all of the winter, whereas two ranged more widely. They left the breeding area at various dates between 1 August and 14 September; three migrated directly from the breeding area while two first moved southwest to stage near Cape Hatteras. All five birds flew directly to the vicinity of Puerto Rico, then moved along the north and east coasts of South America, staging at scattered locations for periods of 3–11 d, before reaching their winter quarters at various dates from 6 September to 26 October. Two birds left their winter quarters on 2 March and 4 April, staged in northern Brazil for 47 and 6 d, then traveled via the Bahamas to reach the breeding site on 1 May. During breeding and post-breeding periods, the birds spent a mean of 7 min each day and virtually no time at night resting on the water, but during the rest of the year they often rested on the water for up to 6 h by day and up to 11 h at night. Leg-mounted geolocators caused several adverse effects but did not reduce survival.

Manipulation of clutch size during incubation has been used in a number of studies to investigate life-history costs of incubation. We increased or decreased clutches of Common Terns Sterna hirundo during incubation and measured subsequent chick growth and productivity. Our results provide little support for the hypothesis that costs of incubation in Common Terns are substantially affected by the number of eggs incubated.

A small, isolated population of Common Terns (10–30 pairs) has bred at Bermuda since at least the 1920s. In September 2003, a hurricane eliminated all the adult males; only females returned in 2004 and these paired together and laid clutches of three–seven infertile eggs. The breeding population was re-established in 2005–06 by four adult males that had been too young to breed in 2003–04. These males paired with females that were probably young and bred with high success (mean 2.6 fledged chicks/pair) through 2009. Two males apparently each mated with two females to form productive trios. The old females continued to pair together and lay infertile eggs, even though males were raising chicks on the same islets. Consequently, the effective population size at the ‘bottleneck’ was only four males and four females. Although the population is now increasing rapidly, it remains critically endangered.

1. Reproductive success often increases with age; however the mechanisms underlying this commonly observed pattern are poorly understood. One mechanism that may be important is a set of physiological responses (the stress response) that allows organisms to evade and cope with stressors, but often inhibits reproduction. 2. If older parents respond less strongly to stressors than younger parents, this age-related difference in the stress response may contribute to the higher reproductive success that often characterizes older parents. 3. Typically the stress response is measured as an increase in plasma glucocorticoid (CORT) concentration, and we have previously reported that stress-induced CORT levels decline with age in the common tern (Sterna hirundo). Another hormone, prolactin (PRL), has been reported to decrease in response to stressors in breeding birds and is often positively associated with parental behaviour. We predicted that like the CORT stress response, the PRL stress response would also be suppressed with age. 4. To test this prediction, we captured known-age, incubating common terns ranging in age from 3 to 29 years and measured stress-induced changes in PRL and CORT levels within the same individuals. 5. We found that PRL levels decreased less rapidly in response to capture and restraint stress in older than in younger parents. In these same birds, we also found that stress-induced maximum CORT levels decreased with age, which is consistent with what we have previously reported for this species. Measures of PRL and CORT were not, however, correlated within individuals. 6. Taken together, these results support the hypothesis that modulations of both the PRL and CORT stress response are flexible hormonal mechanisms that help to account for the increase in reproductive success that occurs with age.

Long-distance breeding dispersal is infrequent among seabirds and has rarely been quantified. Six adult Roseate Terns (Sterna dougallii) that had bred at colony sites in Buzzards Bay, Massachusetts, USA from 2004–2006 switched regions and moved 200–400 km to two colony sites in Maine between 2005 and 2007. Two of the emigrants presumably had nested for at least eight years in Massachusetts before moving to Maine, demonstrating that even long-time philopatric residents of one region may switch to another region.

Although DDE caused reproductive failures in a wide variety of bird species during the 1950s–1970s, the mechanism(s) by which it acted have still not been fully elucidated. This experimental study was designed to test an hypothesis that the primary mechanism by which DDE caused hatching failure in Common Terns (Sterna hirundo) was by disrupting the structure of the eggshell, leading to reduced exchange of O2 and CO2 through the shell to and from the embryo. In the study, gas exchange through two groups of Common Tern eggshells was reduced by 12% or 28% by sealing parts of the surface with acrylic resin. Contrary to predictions from the hypothesis, all treated eggs hatched and there were no other changes in breeding success relative to untreated controls. The result suggests that DDE caused embryonic deaths in Common Terns by mechanisms acting within the egg rather than by modification of the structure or respiratory properties of the shell.

We measured breeding performance of little penguins Eudyptula minor at Phillip Island, Victoria, Australia, during a 21-year period. All birds considered in this paper (n=307) were of known age (2–22 y) and sex, and most were of known, or closely-estimated, pair-bond status (1–8 mates per bird; pair-bond durations 1–13 y). Breeding dates and breeding performance varied markedly from year to year; measures of annual performance were not associated with early breeding. Measures of individual breeding performance (clutch-size, hatching success, chick masses and productivity) were related to early laying, parental age, and duration of pair-bond. Dependence of breeding performance on parental age was curvilinear, levelling off at about 8 y of age. Productivity declined significantly among birds older than 8 y; this decline was not due to events in the last year of breeding (“terminal illness”). Breeding performance increased with duration of pair-bond at least through y 5. Early breeding was significantly related to age and duration of pair-bond. Most of these relationships were stronger among males than among females, and many of them were not significant when females were considered alone. After controlling for other factors, breeding performance varied significantly among birds, but autocorrelations were low and limited to intervals of one year. Parental quality (defined for birds studied in six or more years as the individual bird term in a GLM for productivity controlling for other factors) was not correlated with lifespan or other demographic parameters, but high-quality birds were less prone to change mates and burrows than low-quality birds. We know of no previous study in which simultaneous effects of laying date, age and pair-bond duration on breeding performance were measured, while controlling for year, individual quality and terminal illness.

We used 19 years of mark-recapture/resighting data collected on 11,020 birds from 1988-2006 at five colony sites in Massachusetts, New York, and Connecticut, USA, to examine temporal variation in the survival rates of adult Roseate Terns (Sterna dougallii) during periods of overall population increase (1988-2000) and decline (2000-2006). Roseate Terns nested at only one colony site in Buzzards Bay, Massachusetts at the start of this period, but two more sites in this area were recolonized as the study progressed. Adult survival rates varied temporally in different ways at the different colony sites, but for the five sites combined they did not differ between the period of overall population increase (0.835 ± 0.006 SE) and the period of population decline (0.835 ± 0.008 SE). As expected based on previous work, adult survival from 1991 to 1992 was lowered as a result of a severe hurricane in August 1991. An oil spill in Buzzards Bay in April 2003 did not appear to result in lower survival of the bi...

This paper presents a summary of the four preceding papers and integrates them with previously-published data to compare demographic parameters of Roseate Terns breeding in tropical and temperate regions. Tropical Roseate Terns appear to breed less frequently than temperate birds and raise far fewer chicks to fledging when they do breed. Nevertheless, the three estimates of adult survival rates of tropical populations that were presented in this symposium are lower than those for temperate populations (0.71-0.82 yr-1 vs 0.83-0.90 yr-1). Two estimates of juvenile survival (from fledging to age 1 or 2 years) of tropical birds are slightly higher than comparable estimates for a temperate population, but the differences are not sufficient to offset the lower productivity. Data on ages at first breeding are similar in the two regions. Given their irregular breeding and low productivity, the true survival rates of tropical Roseate Terns must be much higher than those estimated in this symposium. The ad...

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 ...

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.

In response to stressors, most vertebrates elevate secretion of glucocorticoids (CORT) to produce a 'stress response' that enhances survival, but simultaneously inhibits reproduction. Circumstances in which the value of current reproduction is high relative to the value of future reproduction and survival, often lead to suppression of the stress response thus ensuring that critical resources are not diverted away from reproduction. Consistent with this expectation, we have previously reported that the magnitude of the stress response (maximum levels of CORT) declines with age in breeding adults of a long-lived seabird, the common tern (Sterna hirundo). While age-related changes in the stress response may be common in vertebrates, the mechanisms that underlie them are poorly understood. The glucocorticoid stress response is regulated by the hypothalamic-pituitary-adrenal (HPA) axis, and one mechanism that may contribute to an age-related decline in the stress response is changes in adrenal capacity (adrenal sensitivity to ACTH and/or an ability to secrete CORT in response to ACTH). To test this hypothesis, we captured and injected 92 known-aged adult common terns (Sterna hirundo) ranging in age from 3 to 29 years with either a control saline or an experimental adrenocorticotropin (ACTH) solution and measured the effects on stress-induced CORT after 30 min of restraint. In both treatment groups, stress-induced CORT significantly declined with age, suggesting that a decrease in adrenal capacity contributes to a reduction in the stress response in older adults.

Summary A population of 400–600 Acrocephalus orientalis wintering in a Phragmites habitat at 3°N in West Malaysia was studied during four northern hemisphere winters, by means of systematic mist-netting. Data from other study-areas, other habitats and other winters are also used. Intensive mist-netting appears to have made birds move over longer distances than they did in the absence of disturbance, and to have led to the emigration of marked birds from the study-area. Trapping also affected feeding behaviour, resulting in weight-loss; repeated trapping may have increased mortality. Males and females could be separated by means of wing-length in fresh plumage. Females were largely confined to Phragmites; males were more numerous on the edge of reed-beds and in scrub vegetation. Males suffered greater feather-wear than females. As measured by the trapping rate, birds were uniformly distributed throughout the Phragmites habitat, at the same density in different winters. Undisturbed birds used a “home-range” of 1–4 ha, overlapping with 15–50 other individuals. Disturbed birds overlapped with 100–200 others. Individual birds returned to exactly the same “home-range” in successive winters. After correcting for the effects of disturbance and incomplete sampling, the proportion of adults ringed in one winter which returned in the next is estimated as 65% in each of two study-areas. This is a minimum estimate of the annual survival rate for adults. Mean total body-weights were at a minimum in midwinter (November-February). Fat-free weights were also lower in midwinter than in autumn and spring. Body-moult was observed in March and April. Moult of the flight-feathers takes place between July and September, on the breeding grounds or slightly to the south. Females departed on spring migration between 10 and 25 May; males some 11–14 days earlier. Adults arrived in autumn between 8 September and 7 October; males and females often came in in separate “waves”. Females were absent for only about 127 days, about the minimum required for migration, breeding and moult. Dates of migration match those of the more northern breeding populations. Spring departure is later than dates of passage recorded in south China; hence birds of this population appear to make long nights. On average, birds departing in spring carried about 9 g of fat, roughly 40% of total fat-free body-weight. This is about half the energy reserve required for the entire journey. Dates of passage in central China are consistent with a hypothesis that they make the journey (4,500-5,000 km) in two “hops”. A few birds which remained light until very late in the spring showed a significantly lower return rate in the next year. Most birds arriving in autumn appear to have carried 1–2 g of fat, but some were at or below the normal fat-free weight. Many birds appear to have lost weight soon after arrival. Returning ringed adults were amongst the very first birds trapped in September. Individual birds appear to have migrated on very similar dates in different years: many of the dates of trapping differed by 2 days or less in successive years. Trapping rates reached a peak in early October and then declined rapidly, reaching the midwinter level by 21 October. The decline coincided with the differential disappearance of juvenile birds. However, birds collected at this time had adequate fat reserves, and the disappearance appears to have preceded the period of food-shortage. It is suggested that the loss of juvenile birds resulted from behavioural interactions favouring the more dominant individuals, as has been described for several temperate zone residents. The first few weeks in the wintering area may thus be the critical period of mortality during the year. Because birds from different breeding areas are expected to be mixed in the winter-quarters, and vice versa, local mortality factors in winter may affect a number of breeding populations. High adult survival rates have been recorded in several other birds which breed in the temperate zones and winter in the tropics. In general their breeding success appears to be high, so the first-year mortality must be high. The closely related A. arundinaceus, which winters in Africa, differs from A. orientalis in size, wing-shape, timing of spring migration and timing of moult. These differences can be interpreted as adaptations to different environmental (primarily climatic) factors experienced during migration and on the breeding grounds. The segregation of males and females into different habitats probably reduces inter-sexual competition in winter, but this is not necessarily its primary function. Males collected in the evening in Phragmites had smaller fat reserves than females, suggesting that the females are better adapted to this habitat. The large size of the males is probably maintained in part by sexual selection in the breeding season. On the other hand, the size of females and their habitat is probably limited by the specialisation of their nest. These factors would suffice to explain the sexual dimorphism in size and habitat.

In many taxa, reproductive performance increases throughout the lifespan and this may occur in part because older adults invest more in reproduction. The mechanisms that facilitate an increase in reproductive performance with age, however, are poorly understood. In response to stressors, vertebrates release glucocorticoids, which enhance survival but concurrently shift investment away from reproduction. Consequently, when the value of current reproduction is high relative to the value of future reproduction and survival, as it is in older adults, life history theory predicts that the stress response should be suppressed. In this study, we tested the hypothesis that older parents would respond less strongly to a stressor in a natural, breeding population of common terns ( Sterna hirundo ). Common terns are long-lived seabirds and reproductive performance is known to increase throughout the lifespan of this species. As predicted, the maximum level of glucocorticoids released in response to handling stress decreased significantly with age. We suggest that suppression of the stress response may be an important physiological mechanism that facilitates an increase in reproductive performance with age.

We examined the relative contributions of egg size, parental quality and hatch-date to growth and survival of second-hatched chicks (those chicks making the greatest contribution to differences in productivity among pairs) by exchanging clutches among nests of Common Terns Sterna hirundo matched for lay-date (range 13 May to 9 June). The mass of a second-laid egg in an exchanged clutch ranged from 17.70 to 23.80 g. Growth and survival were studied during three periods: early (days 0-3), middle (days 3-12) and late (days 12-25). Both egg mass and hatch-date were important predictors of hatchling mass (positive relationships), although there was no seasonal trend in egg mass. During the middle period, hatch-date was a significant predictor of mass gain and survival (inverse relationships). After controlling for hatch-date, other indices of parental quality made only small contributions to chick mass gain and survival. Our results suggest that although breeding early generally leads to greater overall survival of chicks, several important interactions among egg 'quality', parental quality and early laying may affect breeding success under specific conditions.

The Common Tern (Sterno hirundo) is a long-lived colonial nesting seabird. Previous studies have shown that chick growth and fledging success vary with age of the parental pair and with laying date, with older parents and those nesting earlier being more successful. This study investigated the dependence of breeding performance and one aspect of behavior, defense against conspecifics, on age and laying date. Nest defense behavior was evaluated by recording individual responses to a mirror placed 20 cm from the nest, simulating an unfamiliar intruder within the territory. Most study birds were of known age (3–21 years) from banding as chicks; they were divided into three groups: ≥12, 8–11 and ≤seven years. Responses to the mirror were examined during incubation and at the time of hatching. Older birds nested earlier than younger birds. Chicks reared by older parents gained mass more quickly and survived better than chicks of younger parents. Using a composite score reflecting both the intensity and duration of aggressive responses to the mirror, older birds responded more strongly than younger birds during incubation, but responses were similar at the time of hatching. Older birds reduced their aggressive responses between incubation and hatching, while younger birds increased their responses. We suggest that this contributes to the greater success of older birds, because younger birds expend more time and energy on territorial defense at a time when they need to feed chicks. Our findings are consistent with previous studies and show that Common Tern colonies are finely structured by age and laying date; older and earlier-nesting birds are superior to younger and later birds on several measures of performance. This study suggests that finely-tuned nest defense behavior is one component of the superior performance of old birds.

The evolution of longevity requires a low risk of mortality from extrinsic factors, relative to intrinsic factors, so that individuals that differentially invest in physiological self-maintenance and minimize their annual reproductive costs will maximize lifetime fitness through a prolonged reproductive lifespan. The trade-off between reproductive effort and self-maintenance, as measured by immune function, has been well documented in short-lived birds, but is difficult to demonstrate in long-lived birds. To assess self-maintenance in a long-lived seabird, we measured serum protein levels, including immunoglobulin G (IgG = IgY), in 30 breeding pairs of common terns (Sterna hirundo) and their first-hatched (A) chicks. Most parents were of known age from banding as hatchlings; our sample was selected to contrast young breeders (6-9 years) with very old birds (17-23 years). Body-mass of the parents declined by 5% during the chick-rearing period, while serum protein levels were stable. Serum IgG levels were higher in parents of offspring with faster growth rates, while IgG levels were lower in parents whose broods were reduced by starvation. A-chicks in broods of two had higher IgG levels than singleton chicks. Albumin levels were not related to reproductive performance. Thus, despite adequate statistical power, we could find no evidence for a trade-off between reproduction and self-maintenance in common terns, even in old age. The results are consistent with life-history predictions for long-lived vertebrates, in which selection favors sustained self-maintenance across the reproductive lifespan. The positive relationships between IgG levels and reproductive performance indicate that IgG can be used as an index of parental "quality."

Roseate Tern (Sterna dougallii) nests were monitored at Falkner Island, Connecticut, USA between 1998 and 2002. A total of 586 chicks were sexed and their growth measured during the first three days. These data were used to derive growth parameters and predict survival to fledging with high confidence. In contrast to a previous study in Massachusetts, we found no sex-ratio bias at hatching in any single year or in all years combined, nor was there a bias at fledging in all years combined, or in any single year. This difference is interesting because both colonies exhibit a female-biased sex ratio at breeding. After controlling for other factors, there was no difference in early growth or survival between male and female chicks, consistent with our previous studies and with the hypothesis that differences in growth and survival between males and females observed in other species are due to sexual size dimorphism.

Capsule Kleptoparasitic activities of older chicks from earlier nests did not contribute to late reproductive declines. Aims To determine whether intraspecific interactions, such as kleptoparasitism and aggression, were experienced more frequently by birds breeding late in the season as a result of exposure to breeders at a more advanced stage. If so, to investigate whether this was the cause of the observed seasonal decline in reproductive parameters observed at Bird Island, where nesting density is high and interactions are more probable. Methods Plots were fenced within the colony, exploiting natural variability in distribution of early and peak breeders to create two treatments: plots with only late-laying terns and those with a mixture of early-, peak- and late-layers. Hatching success, productivity and the growth and survival of chicks were measured for all late-laying pairs. Intraspecific interactions, adult attendance and provisioning of chicks were recorded during 9600 minutes of nest observation...

Kleptoparasitism (food theft) is a tactic used opportunistically by many foraging birds, but little is known about its fitness benefits. Here we show that habitual kleptoparasitism by individual parent roseate terns (Sterna dougallii) is associated with consistently superior reproductive performance relative to nonkleptoparasitic (‘‘honest’’) parents, as measured by growth and survival to fledging among their offspring. In broods of two, both chicks of kleptoparasitic parents exhibited superior growth performance during the middle and later stages of the rearing period, relative to chicks of honest parents. This difference was especially pronounced in second-hatched chicks, whose survival is highly variable among years and dependent on food availability. Over a 10-year period, average productivity (number of chicks fledged per pair) was significantly higher among kleptoparasites than among honest parents, with a larger relative difference during years of food shortage. Our study indicates that kleptoparasitism in roseate terns is an important component of parental quality and provides the first evidence that food stealing is associated with enhanced fitness in a facultatively kleptoparasitic seabird. Key words: breeding success, foraging behavior, kleptoparasitism, parental quality, roseate tern, Sterna dougallii. [Behav Ecol]

In 1999, we compared demographic and biological parameters in Common Terns (Sterna hirundo) among three colonies located 10-26 km apart in Buzzards Bay, Massachusetts, USA. The three colony sites differed primarily in size, number of pairs, and length of occupancy by terns: Penikese Island (8 ha, 132 pairs, 3 yr), Ram Island (1.1 ha, 1,900 pairs, 8 yr), Bird Island (0.6 ha, 1,800 pairs, >65 yr). This study compared parental ages and origins, nesting phenology, clutch-size, chick growth rates, productivity, chick diets, feeding rates and foraging trip times among the three colonies. Common Terns breeding at the new colony on Penikese Island were significantly younger (mean age 6.8 yr) and laid later (mean laying date 25 May), had higher productivity (2.2 fledged chicks/pair) and higher chick growth rates than those at the old colony on Bird Island (means 11.7 yr, 20 May, 0.8 chicks/pair, respectively). Feeding rates were highest and foraging trip times for all types of prey were shortest at Penike...