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Peter H. Becker - One of the best experts on this subject based on the ideXlab platform.

  • Concentrations of hormones during the mid-incubation period in kleptoparasitic and honest Common Terns Sterna Hirundo
    Acta Ornithologica, 2017
    Co-Authors: Carla A. Paterlini, Juliane Riechert, Germán Oscar García, Peter H. Becker
    Abstract:

    Kleptoparasitism is a well-known foraging strategy used by many colonial seabirds. The expression of this behavior can reduce the cost of foraging during the breeding season and ultimately this can be reflected in physiological parameters. Here we analyzed the relationship between the trophic strategy of Common Terns Sterna Hirundo and two hormones, that are known to be involved in decision-making during the reproductive cycle and foraging activities: corticosterone (CORT) and prolactin (PRL). The study was conducted during the breeding seasons 2012–2014 at the Banter See colony in northern Germany where individuals with different foraging strategies were identified and monitored since 2008. We studied the concentration of hormones in two groups of birds: kleptoparasitic individuals i.e. individuals who steal the food captured by another individual, and honest individuals i.e. individuals who obtain the food on their own. Blood samples were obtained during the mid-incubation period using a non-invasive technique. Both hormones showed no significant relationship to each other. CORT concentration was similar in both groups of birds. However, the concentration of PRL was higher in parasitic than honest individuals in 2014. In addition, CORT modelling indicated a year effect (higher CORT in 2013), and PRL modelling indicated a significant effect of year (higher PRL in 2012) and a significant interaction between year and the trophic strategy in 2014. The results show no clear relationship between the feeding strategy and studied corticosterone and prolactin levels.

  • New Microsatellite Markers for the Common Tern (Sterna Hirundo) Developed with 454 Shot-Gun Pyrosequencing
    The Open Ornithology Journal, 2016
    Co-Authors: Susann Janowski, Peter H. Becker, Ina Gross, Hedwig Sauer-gürth, Dieter Thomas Tietze, Markus A. Grohme, Marcus Frohme, Michael Wink
    Abstract:

    Long term studies, focusing on population- and socio-biology research, require the unequivocal identification of individuals. DNA studies with Short Tandem Repeats (STR loci) became a widespread tool in population genetics. We used the next-generation sequencing (NGS) approach with 454 shot-gun pyrosequencing to identify 13 new polymorphic STR loci for the Common Tern, Sterna Hirundo. To enlarge the marker set we added two more loci originally developed for Black-legged Kittiwake (Rissa tridactyla) and Red-billed Gull (Chroicocephalus scopulinus) and arranged these 15 loci into three multiplex PCR panels for high throughput genotyping. Loci characterization demonstrated that our marker set is of high quality. A PIC value of about 0.67 and a power of exclusion value of 0.99 were reached. Deviation from Hardy-Weinberg expectations of some loci and low frequencies for null alleles are interpreted as a result of inbreeding and founder effect in the investigated tern colony. We used a test data set of this well-studied breeding colony of Common Tern at Banter Lake, Wilhelmshaven, Germany, to perform a parentage test. Parent-chick relationships, known from the social pedigree of that colony, were compared with genetically calculated ones. In order to test our markers and the used parentage program COLONY, we conducted six competing data sets with varying completeness of included parental genotypes. By including fully sampled parent pairs of known family assignment, results were correct for nest mates, single parents and parent pairs. Our marker set provides a powerful tool to investigate life-time reproductive success and other issues of population and socio-biology for Common Terns, e.g. in the aforementioned colony monitored for decades.

  • Predicting reproductive success from hormone concentrations in the common tern (Sterna Hirundo) while considering food abundance.
    Oecologia, 2014
    Co-Authors: Juliane Riechert, Peter H. Becker, Olivier Chastel
    Abstract:

    In birds, reproductive success is mainly a function of skill or environmental conditions, but it can also be linked to hormone concentrations due to their effect on behavior and individual decisions made during reproduction. For example, a high prolactin concentration is required to express parental behaviors such as incubation or guarding and feeding the young. Corticosterone level, on the other hand, is related to energy allocation or stress and foraging or provisioning effort. In this study, we measured individual baseline prolactin and corticosterone between 2006 and 2012 in breeding common terns (Sterna Hirundo) using blood-sucking bugs. Reproductive parameters as well as prey abundance on a local and a wider scale were also determined during this period. Baseline prolactin and corticosterone varied significantly between years, as did breeding success. At the individual level, prolactin was positively and corticosterone was negatively linked to herring and sprat abundance. At the population level, we also found a negative link between corticosterone and prey abundance, probably reflecting overall foraging conditions. High prolactin during incubation was mainly predictive of increased hatching success, potentially by supporting more constant incubation and nest-guarding behavior. It was also positively linked to a lesser extent with fledging success, which could indicate a high feeding rate of young. Corticosterone concentration was positively related to high breeding success, which may be due to increased foraging activity and feeding of young. In general, our study shows that baseline prolactin and corticosterone levels during incubation can predict reproductive success, despite the presence of an interval between sampling and hatching or fledging of young.

  • Sex-specific traits in Common Tern Sterna Hirundo chicks: associations with rearing environment, parental factors and survival
    Journal of Ornithology, 2014
    Co-Authors: María M. Benito, Jacob González-solís, Peter H. Becker
    Abstract:

    Offspring phenotypic variation has important consequences for the future survival, reproductive success and individual fitness of nestlings, but the sex-specific reproductive value and fitness returns for parents of this variation have only rarely been explored. We analysed twelve phenotypic traits of nestling Common Terns (Sterna Hirundo) in relation to their sex, age and hatching date, and explored whether sexual differences in these traits were associated with the rearing environment and survival. In addition, we studied sex-specific differences in offspring phenotype related to parental factors, since the existence of sexual dimorphism may reflect differential parental investment. Bill–head length and mediated immune response varied in relation to offspring sex, with males showing larger values than females. Immune response was also affected by environmental (year), rearing (competition over 14 days old) and parental (clutch size) factors. None of the morphological, serological and immunological variables were associated with chick mortality, but female nestlings that did not survive had suffered longer periods of within-brood competition. Although some parental traits influenced offspring phenotype, sexual differences among nestlings did not vary in relation to parental age, mass or arrival date, which may imply that there is no great difference in cost between raising sons and raising daughters, and thus no adjustment of parental effort in relation to nestling sex. However, the evidence that immune response was higher for sons in larger clutches that were raised with siblings indicates a difference in the developmental strategies for sons and daughters, which may be related to their reproductive value. These results therefore provide evidence of certain pathways for parental sex allocation that may differentially affect sons and daughters.

  • Stealing food from conspecifics: spatial behavior of kleptoparasitic Common Terns Sterna Hirundo within the colony site
    Journal of Ornithology, 2014
    Co-Authors: Germán Oscar García, Marco Favero, Juliane Riechert, Peter H. Becker
    Abstract:

    Amongst seabirds, kleptoparasitism is one of the most common types of exploitation in which individuals compete for food already procured by another forager. Here, we analyzed the within-colony spatial movements and foraging of transponder-marked Common Terns (Sterna Hirundo) during the chick-rearing period in relation to the terns’ trophic strategy (kleptoparasitic vs. honest). Attendance patterns (time spent at the colony site per day, number and locations of resting platforms used) were compared between kleptoparasitic (N = 11) and honest individuals (N = 26). A total of 725 kleptoparasitic attacks were recorded during the chick-rearing period at the colony site. We found sex differences in the tactic used for stealing food and the area chosen for attacks: females attacked in the vicinity of their nest, while males attacked further away. Significant differences were found between both groups in the spatial pattern: kleptoparasites (particularly males) used more resting platforms and moved more widely across the colony site than honest individuals, and parasitic females were present in the colony longer during the day than honest ones. Our results show a differential use of the colony site dependent on the foraging strategy. Parasitic birds used the colony site as a foraging patch, monitoring the colony and looking for kleptoparasitic feeding opportunities without compromising their parental roles. In contrast, honest individuals spent much time outside the colony foraging for their chicks.

Ian C T Nisbet - One of the best experts on this subject based on the ideXlab platform.

  • Breeding performance of Common Terns (Sterna Hirundo) does not decline among older age classes
    The Auk, 2020
    Co-Authors: Ian C T Nisbet, David T. Iles, Andrew Kaneb, Carolyn S. Mostello, Stéphanie Jenouvrier
    Abstract:

    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.

  • Consequences of Renesting in Common Terns (Sterna Hirundo): Changes in Clutch Size, Egg Mass, and Productivity
    Waterbirds, 2020
    Co-Authors: Ian C T Nisbet
    Abstract:

    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.

  • Changes in White Blood Cell Parameters of Common Terns (Sterna Hirundo) Exposed to Low Levels of Oil
    Waterbirds, 2015
    Co-Authors: Ian C T Nisbet, Christine V. Fiorello, Florina S. Tseng, Victor Apanius
    Abstract:

    Abstract. 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...

  • Age-dependent breeding dispersal and adult survival within a metapopulation of Common Terns Sterna Hirundo
    Ibis, 2014
    Co-Authors: André R. Breton, Carolyn S. Mostello, Ian C T Nisbet, Jeremy J Hatch
    Abstract:

    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

  • Decreased Hematocrits in Common Terns (Sterna Hirundo) Exposed to Oil: Distinguishing Oil Effects from Natural Variation
    Waterbirds, 2013
    Co-Authors: Ian C T Nisbet, Florina S. Tseng, Victor Apanius
    Abstract:

    Abstract. 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...

Jeremy J Hatch - One of the best experts on this subject based on the ideXlab platform.

  • Age-dependent breeding dispersal and adult survival within a metapopulation of Common Terns Sterna Hirundo
    Ibis, 2014
    Co-Authors: André R. Breton, Carolyn S. Mostello, Ian C T Nisbet, Jeremy J Hatch
    Abstract:

    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

  • Piracy at the Nest: Factors Driving Kleptoparasitic behaviour of Common Tern Sterna Hirundo Chicks
    Acta Ornithologica, 2012
    Co-Authors: Stephen A. Oswald, Jeremy J Hatch, Jennifer Marie Arnold, Ian C T Nisbet
    Abstract:

    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.

  • costs of incubation in common terns Sterna Hirundo replication and extension of a clutch enlargement experiment
    Ibis, 2011
    Co-Authors: Jeremy J Hatch, Ian C T Nisbet
    Abstract:

    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.

  • Costs of incubation in Common Terns Sterna Hirundo: replication and extension of a clutch‐enlargement experiment
    Ibis, 2010
    Co-Authors: Jeremy J Hatch, Ian C T Nisbet
    Abstract:

    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.

  • Hematology and Absence of Hemoparasites in Breeding Common Terns (Sterna Hirundo) from Cape Cod, Massachusetts
    Journal of zoo and wildlife medicine : official publication of the American Association of Zoo Veterinarians, 2009
    Co-Authors: Christine V. Fiorello, Jeremy J Hatch, Ian C T Nisbet, Carolyn Corsiglia, Mark A. Pokras
    Abstract:

    Abstract In June and July 1995, 98 breeding common terns (Sterna Hirundo) were captured, weighed, and bled as a part of ongoing research on the population health and reproductive biology of this species of special concern. Packed cell volume, total and differential white blood cell counts, and blood smears were obtained. Blood smears from 75 terns were examined. No hemoparasites were found. There were some significant differences among hematologic parameters in birds from different islands, and between birds nesting earlier versus later in the season, but there were no significant differences associated with body mass, sex, or age. The absence of hemoparasites in the blood smears of these terns is noteworthy, especially because other studies of seabirds (including Charadriiformes) have revealed low prevalences of hematozoa.

Michael Gochfeld - One of the best experts on this subject based on the ideXlab platform.

  • Nest and Colony Site Selection in Common Terns (Sterna Hirundo) in Mongolia
    Waterbirds, 2016
    Co-Authors: Joanna Burger, Michael Gochfeld
    Abstract:

    Abstract. The biology of the Common Tern (Sterna Hirundo) has been studied on several continents, but information from central Asia is limited. Colony characteristics and nest site selection of Common Terns were studied in the desert and steppe of Mongolia to determine factors that influence their choices. Common Terns nested in marshy areas around small ponds, on sand bars adjacent to a lake in the Gobi, and on small islands in a water treatment plant in the steppe of Ulaanbaatar. In the Gobi, they nested with Pied Avocets (Recurvirostra avosetta) that defended the colony site, while the terns left. Common Terns selected colony sites surrounded by water and muck/ mud, and nest sites with good visibility. Their choice of colony and nest sites seemed to be a compromise between avoiding flooding, avoiding nest trampling by livestock, and finding any safe nesting place to avoid terrestrial predators.

  • Metal levels in eggs of common terns (Sterna Hirundo) in New Jersey: temporal trends from 1971 to 2002.
    Environmental research, 2004
    Co-Authors: Joanna Burger, Michael Gochfeld
    Abstract:

    Managers and public policy makers require information on the status of and trends in contaminant levels in organisms to assess ecosystem health. Seabirds are excellent bioindicators because they are long-lived, feed at different trophic levels, and are at the top of the food chain, and many are abundant and widely distributed. They can reveal spatial or temporal trends in contaminant levels. In this paper, we examine temporal trends in the levels of cadmium, chromium, lead, manganese, mercury, and selenium in eggs from common terns (Sterna Hirundo) nesting on several salt marsh islands in Barnegat Bay, New Jersey. We test the null hypothesis that there are no temporal differences in levels of cadmium, lead, and mercury from 1971 to 2002 and in chromium, manganese, and selenium from 1992 to 2002. Arsenic was also analyzed in recent years. Levels were highest for manganese, followed by selenium, mercury, arsenic, lead, chromium, and cadmium. The eggs of Barnegat Bay common terns show a decline in levels of cadmium, chromium, and lead. Mercury declined from 1971 to 1982, increased dramatically in 1999, and declined thereafter. Manganese, an essential element, showed a decline (except for 2001), and selenium declined initially, but then remained stable. The data indicate that common terns can serve as useful bioindicators of temporal trends in exposure and that some of the metals of concern in estuarine environments (lead, cadmium) have declined over the past 30 years, although mercury levels are higher than in the early 1980s. The spike in 1999 is unexplained.

  • Spatial and temporal patterns in metal levels in eggs of common terns (Sterna Hirundo) in New Jersey.
    The Science of the total environment, 2003
    Co-Authors: Joanna Burger, Michael Gochfeld
    Abstract:

    Seabirds are excellent subjects for examination of metals because they feed at different trophic levels, including as top-level piscivores, they are long-lived, and many are abundant and widely distributed. In this paper we examine the levels of arsenic, cadmium, chromium, lead, manganese, mercury and selenium in eggs from common terns (Sterna Hirundo) nesting on five saltmarsh islands in Barnegat Bay, New Jersey from 2000 to 2002. We test the null hypothesis that there were no locational or temporal differences from 2000 to 2002. There were significant locational differences in all metals in some years, although the differences were not large. The levels of most metals do not seem sufficiently high to cause adverse effects, although the levels of mercury in eggs of some common terns from the bay are within the range known to cause adverse effects. Mercury in common tern eggs may be a contributing cause to their local decline.

  • Heavy metal and selenium levels in feathers of known-aged common terns (Sterna Hirundo)
    Archives of environmental contamination and toxicology, 1994
    Co-Authors: Joanna Burger, Ian C T Nisbet, Michael Gochfeld
    Abstract:

    Concentrations of five metals and selenium in the breast feathers of known-aged common terns (Sterna Hirundo) were examined at a breeding colony in Massachusetts, USA. Concentrations of selenium, chromium, and manganese increased significantly with age among adults (2–21 years old), whereas concentrations of mercury, cadmium, and lead did not. Concentrations of cadmium, selenium and manganese were lower in fledglings (20–23 days old) than in adults. Concentrations of mercury, however, were higher in fledglings than in adults, and concentrations of chromium were higher in fledglings than in young adults, probably reflecting higher exposure to these metals in the breeding area than in the winter quarters where the adults' feathers were grown. At least for mercury, excretion of metals into the feathers at each molt was an efficient protective mechanism, preventing continued accumulation in the body with increasing age.

  • Cadmium and lead in common terns (Aves: Sterna Hirundo): Relationship between levels in parents and eggs
    Environmental Monitoring and Assessment, 1991
    Co-Authors: Joanna Burger, Michael Gochfeld
    Abstract:

    We analyzed cadmium and lead levels in feathers of mated pairs of common terns ( Sterna Hirundo ) and in their eggs to determine if metal levels in eggs correlated with female levels, and whether there were intrapair and intermetal correlations. Eggs had significantly lower lead levels (89 ng g^-1) and cadmium levels (4.0 ng g^-1) than adult feathers (500 and 50 ng g^-1 respectively). Adult females had higher metal levels than males. Cadmium and lead levels were correlated across families for females, males and eggs. Lead, but not cadmium, levels were correlated in females and their eggs.

Jennifer Marie Arnold - One of the best experts on this subject based on the ideXlab platform.

  • Nocturnal Sleep Behavior and Vigilance of Incubating Common Terns (Sterna Hirundo) at Two Inland Breeding Colonies
    Waterbirds, 2020
    Co-Authors: Jenna Diehl, Stephen A. Oswald, Zoe O. Korpi, Paul D. Curtis, Jennifer Marie Arnold
    Abstract:

    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.

  • First confirmed record of a Common Tern Sterna Hirundo breeding at one year of age
    Bird Study, 2013
    Co-Authors: Jennifer Marie Arnold, Stephen A. Oswald
    Abstract:

    Capsule The first confirmed record of breeding by a one-year-old Common Tern Sterna Hirundo is revealed by ringing evidence, despite second-summer plumage characteristics.

  • Piracy at the Nest: Factors Driving Kleptoparasitic behaviour of Common Tern Sterna Hirundo Chicks
    Acta Ornithologica, 2012
    Co-Authors: Stephen A. Oswald, Jeremy J Hatch, Jennifer Marie Arnold, Ian C T Nisbet
    Abstract:

    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.

  • Effects of egg size, parental quality and hatch-date on growth and survival of Common Tern Sterna Hirundo chicks
    Ibis, 2006
    Co-Authors: Jennifer Marie Arnold, Jeremy J Hatch, Ian C T Nisbet
    Abstract:

    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.

  • Seasonal declines in reproductive success of the common tern Sterna Hirundo: timing or parental quality?
    Journal of Avian Biology, 2004
    Co-Authors: Jennifer Marie Arnold, Jeremy J Hatch, Ian C T Nisbet
    Abstract:

    Reproductive success declines over the course of the breeding season in many bird species. Two categories of hypothesis have been evoked to explain this decline. The “timing” hypothesis suggests that seasonal declines in breeding success are attributable to the date of laying. The “parental quality” hypothesis suggests that seasonal declines result from the fact that young, inexperienced, or low quality birds breed later in the season. To evaluate the relative importance of timing and parental quality, egg exchanges and removals were used to manipulate hatching dates of common terns Sterna Hirundo. Indices of quality, attendance, provisioning rates, and reproductive success of birds in three experimental groups (delayed hatch pairs, advanced hatch pairs, and pairs induced to relay) were compared to those of date-matched controls. Pairs that hatched chicks early raised more chicks than pairs hatching chicks late in the season, regardless of initial laying date. This suggests that hatching chicks early is advantageous in itself. Our results, however, also support the parental quality hypothesis. There was a significant negative relationship between natural laying date and fledging success, independent of hatching date. Differences in chick growth and survival suggest that higher quality adults may be able to compensate for the disadvantages of late hatching dates and achieve similar reproductive success to that of pairs hatching chicks early. We found that pairs hatching chicks late in the season were subject to more incidents of kleptoparasitism than those hatching chicks early. This may be a proximate factor contributing to seasonal declines in reproductive success for common terns, although such a mechanism would not be likely in non-colonial species. Failure to control for egg quality may have biased the results of some prior egg exchange experiments. Additionally, altered cost of incubation may be an unavoidable confounding factor in studies designed to manipulate timing of breeding.