Luxury in freshwater and stress at sea? The foraging of the Common Tern <i>Sterna hirundo</i>

Becker, Peter; Frank, Dietrich; Wagener, Martin

doi:10.1111/j.1474-919x.1997.tb04624.x

Cited by 25 publications

(18 citation statements)

References 9 publications

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“…There is a vast literature in the field of seabird feeding ecology showing how many of these species rely on juvenile and small-sized fish occurring in these shallow waters (ISACCH et al, 2010). The high concentration of small-sized fish and the higher spatio-temporal predictability that estuarine resources might provide, buffering the lower predictability of marine resources, are probably among the causes which explain the congregation of marine and coastal birds in these areas (BECKER et al, 1997). Our results on the diet of the Black skimmer at Mar Chiquita were in line with previous studies (MARIANO-JELICICH et al, 2003).…”

Section: Discussionsupporting

confidence: 82%

Fish composition and prey utilization of the black skimmer (Rynchops niger) in mar Chiquita coastal lagoon, Argentina

2014

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A B S T R A C TLagoons along the western coast of the South Atlantic Ocean shelter high densities of juvenile fish and are key areas for several seabirds that rely on the resources offered by this kind of ecosystem. The objective of this study was to analyze fish composition and abundance in shallow-water areas of the estuarine region of Mar Chiquita Coastal Lagoon (Argentina) and the diet composition of the Black skimmer (Rynchops niger) during its non-breeding season as well as evaluating its inter-annual variations. Fish were sampled with a beach-seine net and the skimmers' diet was analyzed from their pellets. The estuarine-dependent marine fishes were the best represented bio-ecological category followed by freshwater fishes. Significant differences were observed in fish abundance and composition between and within years. Species richness was higher during the summer season and during the first year sampled. The occurrence of freshwater fishes as an important and diverse group of the Mar Chiquita estuarine area contrasted with previous reports. The diet of the Black skimmer included freshwater, estuarine and marine fish species. Skimmers forage in the shallow waters of the estuarine area of the Mar Chiquita Coastal lagoon though little similarity was observed between its diet and local fish abundance. These results emphasize the importance of performing these evaluations in order to improve the quality of studies and the interpretations of top predators foraging ecology. R E S U M OAs lagoas costeiras do Oceano Atlântico Sul abrigam altas densidades de peixes juvenis e são áreas-chave para diversas aves marinhas que dependem dos recursos oferecidos por esses ecossistemas. O objetivo do presente trabalho foi analisar a abundância e a composição de peixes na região estuarina da Lagoa Costeira Mar Chiquita (Argentina), a dieta do talha-mar (Rynchops niger) e as variações interanuais. Os peixes foram coletados com uma rede de praia tipo picaré e a dieta do talha-mar analisada a partir de suas fezes. O peixe-marinhos dependentes do estuário foram a categoria bioecológica melhor representada, seguido por peixes de água doce. Foram observadas diferenças intranuais e interanuais significativas na abundância e composição da ictiofauna. A riqueza de espécies foi maior durante o verão e no primeiro ano da amostragem. A ocorrência de peixes de água doce como um grupo importante e diversificado na área estuarina do Mar Chiquita contrasta com resultados de estudos anteriores realizados na área. A dieta do talha-mar incluiu peixes de água doce, estuarinos e marinhos. Apesar dessa ave se alimentar em águas rasas da área estuarina do Mar Chiquita, uma baixa similaridade entre sua dieta e abundância local de peixes foi observada. Esses resultados reforçam a importância da realização de avaliações a fim de proporcionar avanço nos estudos e melhorar as interpretações sobre a ecologia alimentar de predadores de topo.

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Section: Discussionsupporting

confidence: 82%

Fish composition and prey utilization of the black skimmer (Rynchops niger) in mar Chiquita coastal lagoon, Argentina

2014

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“…Available evidence suggests that overall, the marine environment may be more energetically costly than freshwater environments because of higher thermoregulatory costs (Guti errez et al 2012), lower or less predictable food availability [such as when foraging over marine predators (Safina 1990;Goyert, Manne & Veit 2014) or in tidal habitats (Becker, Frank & Wagener 1997;Guti errez et al 2012)], greater competition for food resources (Safina 1990;Tims et al 2004), less suitable prey (Massias & Becker 1990) and/or increased costs of osmoregulation (Guti errez et al 2012). Spatial and temporal variability in biotic and abiotic factors may lead to potentially large variation in ecological stress within each environment, making this difficult to demonstrate.…”

Section: Parental Strategiesmentioning

confidence: 99%

Energetic constraint of non‐monotonic mass change during offspring growth: a general hypothesis and application of a new tool

Arnold

Nisbet²,

Oswald

2016

Journal of Animal Ecology

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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.

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“…In common terns, both pairmates share incubation, and one foraging flight lasts 2-3 h on average (Frank and Becker 1992). During the incubation bouts, breeding birds lost about 14 g of body mass (table 1; see also Becker 1992 andBecker et al 1997). Following our sampling schedule, individuals in the satiated state were sampled after an incubation interval significantly shorter than that during the hungry state (Z p Ϫ6.154, P !…”

Section: Sampling Schedulementioning

confidence: 99%

Regulation of Breeding Behavior: Do Energy-Demanding Periods Induce a Change in Prolactin or Corticosterone Baseline Levels in the Common Tern (Sterna hirundo)?

Riechert¹,

Chastel²,

Becker³

2014

Physiological and Biochemical Zoology

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Hormones are involved in reproductive decisions, linking environmental cues and body condition and adapting behavior. Mass loss is often accompanied by decreased prolactin and increased corticosterone concentrations, influencing incubation and brooding behavior and ultimately triggering nest desertion. Using blood-sucking bugs (Dipetalogaster maxima), we measured baseline prolactin, corticosterone, and ketone body values in incubating common terns (Sterna hirundo) between 2006 and 2009 during energy-demanding periods: 50 pairs were sampled hungry (after an incubation bout) and again fed (after foraging). In a second approach, we sampled 57 other pairs (experienced and inexperienced birds) three times over their individual breeding period, because reproduction, especially chick rearing, is a very energy-demanding process. In line with the common physiological pattern of fasting, we found significantly lower baseline prolactin values in hungry terns, which were negatively related to mass loss over the incubation bout, whereas corticosterone and ketone body levels were marginally increased. Compared to that in the incubation phase, the prolactin level dropped after hatching of chicks in inexperienced birds, perhaps indicating lower parental expenditure. Corticosterone, on the other hand, increased after hatching in males, probably linked to higher foraging activity, as males mainly deliver food during the first days. These energy-demanding periods clearly influenced hormones and ketone bodies, maybe reinforced by the low energy margin of this small seabird species, but energy reserves were not depleted to a level affecting behavior or reproductive success.

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Luxury in freshwater and stress at sea? The foraging of the Common Tern Sterna hirundo

Cited by 25 publications

References 9 publications

Fish composition and prey utilization of the black skimmer (Rynchops niger) in mar Chiquita coastal lagoon, Argentina

Fish composition and prey utilization of the black skimmer (Rynchops niger) in mar Chiquita coastal lagoon, Argentina

Energetic constraint of non‐monotonic mass change during offspring growth: a general hypothesis and application of a new tool

Regulation of Breeding Behavior: Do Energy-Demanding Periods Induce a Change in Prolactin or Corticosterone Baseline Levels in the Common Tern (Sterna hirundo)?

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