scholarly journals Parental Investment Under Predation Threat in Incubating Common Eiders (Somateria mollissima): A Hormonal Perspective

2021 ◽  
Vol 9 ◽  
Author(s):  
Bertille Mohring ◽  
Frédéric Angelier ◽  
Kim Jaatinen ◽  
Charline Parenteau ◽  
Markus Öst
Keyword(s):  
Predation Risk ◽  
Body Condition ◽  
Parental Investment ◽  
Nest Predation ◽  
Hatching Success ◽  
Reproductive Investment ◽  
Somateria Mollissima ◽  
Common Eiders ◽  
Adaptation Hypothesis ◽  
The Impact

Predation risk affects the costs and benefits of prey life-history decisions. Predation threat is often higher during reproduction, especially in conspicuous colonial breeders. Therefore, predation risk may increase the survival cost of breeding, and reduce parental investment. The impact of predation risk on avian parental investment decisions may be hormonally mediated by prolactin and corticosterone, making them ideal tools for studying the trade-offs involved. Prolactin is thought to promote parental care and commitment in birds. Corticosterone is involved in allostasis and may either mediate reduced parental investment (corticosterone-fitness hypothesis), or promote parental investment through a reallocation of resources (corticosterone-adaptation hypothesis). Here, we used these hormonal proxies of incubation commitment to examine the impact of predation risk on reproduction in common eiders (Somateria mollissima) breeding in the Baltic Sea. This eider population is subject to high but spatially and temporally variable predation pressure on adults (mainly by the white-tailed eagle Haliaeetus albicilla and introduced mammalian predators) and nests (by the adult predators and exclusive egg predators such as hooded crows Corvus cornix). We investigated baseline hormonal levels and hatching success as a function of individual quality attributes (breeding experience, female and duckling body condition), reproductive investment (clutch weight), and predation risk. We expected individuals nesting in riskier environments (i.e., on islands where predation on adults or nests is higher, or in less concealed nests) to reduce their parental investment in incubation, reflected in lower baseline prolactin levels and either higher (corticosterone-fitness hypothesis) or lower (corticosterone-adaptation hypothesis) baseline corticosterone levels. Contrary to our predictions, prolactin levels showed a positive correlation with nest predation risk. The unexpected positive relationship could result from the selective disappearance of low-quality females (presumably having low prolactin levels) from risky sites. Supporting this notion, female body condition and hatching success were positively correlated with predation risk on females, and baseline prolactin concentrations were positively correlated with duckling body condition, a proxy of maternal quality. In line with the corticosterone-adaptation hypothesis, baseline corticosterone levels increased with reproductive investment, and were negatively associated with nest predation risk. Hatching success was lower on islands where nest predation risk was higher, consistent with the idea of reduced reproductive investment under increased threat. Long-term individual-based studies are now needed to distinguish selection processes occurring at the population scale from individually plastic parental investment in relation to individual quality and variable predation risk.

scholarly journals Glucocorticoids, state-dependent reproductive investment and success in the face of danger in a long-lived bird

2020 ◽  
Author(s):  
Kristina Noreikienė ◽  
Kim Jaatinen ◽  
Benjamin B. Steele ◽  
Markus Öst
Keyword(s):  
Predation Risk ◽  
Telomere Length ◽  
Clutch Size ◽  
Body Condition ◽  
Nest Predation ◽  
Hatching Success ◽  
Reproductive Investment ◽  
Trade Off ◽  
Relative Telomere Length ◽  
Future Reproduction

AbstractGlucocorticoid hormones may mediate trade-offs between current and future reproduction. However, understanding their role is complicated by predation risk, which simultaneously affects the value of the current reproductive investment and elevates glucocorticoid levels. Here, we shed light on these issues in long-lived female Eiders (Somateria mollissima) by investigating how current reproductive investment (clutch size) and hatching success relate to faecal glucocorticoid metabolite [fGCM] level and residual reproductive value (minimum years of breeding experience, body condition, relative telomere length) under spatially variable predation risk. Our results showed a positive relationship between colony-specific predation risk and mean colony-specific fGCM levels. Clutch size and female fGCM were negatively correlated only under high nest predation and in females in good body condition, previously shown to have a longer life expectancy. We also found that younger females with longer telomeres had smaller clutches. The drop in hatching success with increasing fGCM levels was least pronounced under high nest predation risk, suggesting that elevated fGCM levels may allow females to ensure some reproductive success under such conditions. Hatching success was positively associated with female body condition, with relative telomere length, particularly in younger females, and with female minimum age, particularly under low predation risk, showing the utility of these metrics as indicators of individual quality. In line with a trade-off between current and future reproduction, our results show that high potential for future breeding prospects and increased predation risk shift the balance toward investment in future reproduction, with glucocorticoids playing a role in the resolution of this trade-off.

scholarly journals Effects of Data-Loggers Implanted for a Full Year in Female Common Eiders

The Condor ◽  
2002 ◽  
Vol 104 (2) ◽  
pp. 448-452 ◽  
Author(s):  
Magella Guillemette ◽  
Anthony J. Woakes ◽  
Annette Flagstad ◽  
Patrick J. Butler
Keyword(s):  
Harmful Effect ◽  
Body Cavity ◽  
The Body ◽  
Control Group ◽  
Somateria Mollissima ◽  
Aerodynamic Properties ◽  
Data Loggers ◽  
Common Eiders ◽  
The Baltic ◽  
The Impact

Abstract Data-loggers can be implanted into the body cavities of birds to monitor their physiology and behavior. This technology opens the potential for year-round monitoring, as long as data-loggers can be retrieved one year later and the implantation does not alter the bird's health or behavior. We tested the impact of carrying data-loggers on reproductive parameters of nine female Common Eiders breeding in the Baltic Sea. We minimized disturbance and maximized return rates of experimental females by implanting data-loggers during the second half of the incubation period and by choosing early breeders, which were presumably high quality individuals. All experimental females came back to the study plot the year following implantation. Using a before-after approach applied to an experimental and a control group, we found no evidence that carrying data-loggers had any harmful effect on laying dates, clutch sizes, or hatching success of experimental females. It appears that data-loggers implanted in the body cavities of female Common Eiders do not interfere with their reproductive activities. Explanations for this result are that data-loggers are small compared to body mass (<1%), and their implantation into the body cavity does not alter the hydrodynamic or aerodynamic properties of these diving birds. Efectos de Medidores Implantados por un Año Completo en Hembras de Somateria mollissima Resumen. Pequeños medidores (i.e., “data-loggers”) pueden ser implantados en las cavidades corporales de las aves para monitorear su fisiología y comportamiento. Esta tecnología abre el potencial para realizar monitoreos a lo largo del año, siempre y cuando los medidores puedan ser recuperados un año más tarde y éstos no afecten la salud o el comportamiento de las aves. Evaluamos el impacto de llevar medidores sobre parámetros reproductivos de nueve hembras de la especie Somateria mollissima que se estaban reproduciendo en el Mar Báltico. Minimizamos el disturbio y maximizamos las tasas de retorno de las hembras experimentales implantando los medidores durante la segunda mitad del período de incubación y escogiendo aquellas que se reprodujeron al comienzo de la estación, que presumiblemente eran individuos de alta calidad. Todas las hembras experimentales regresaron al sitio de estudio al año siguiente de la implantación. Utilizando un método de antes y después aplicado a un grupo experimental y a uno de control, no encontramos evidencia de que llevar medidores tenga algún efecto negativo sobre la fecha de postura, el tamaño de la nidada o el éxito de eclosión de las hembras experimentales. Al parecer, los medidores implantados en las cavidades corporales de las hembras de S. mollissima no interfieren con sus actividades reproductivas. Las explicaciones para este resultado son que los medidores son pequeños en comparación con la masa corporal (<1%), y que su implantación en la cavidad corporal no altera las propiedades hidrodinámicas ni aerodinámicas de estas aves buceadoras.

Body condition and the grouping behavior of brood-caring female common eiders ( Somateria mollissima )

2003 ◽  
Vol 54 (5) ◽  
pp. 451-457 ◽  
Author(s):  
Markus �st ◽  
Ron Ydenberg ◽  
Kai Lindstr�m ◽  
Mikael Kilpi
Keyword(s):  
Body Condition ◽  
Somateria Mollissima ◽  
Common Eiders ◽  
Grouping Behavior

Intraclutch egg-size variation and hatching success in the common eider

1993 ◽  
Vol 71 (3) ◽  
pp. 544-549 ◽  
Author(s):  
Gregory J. Robertson ◽  
Fred Cooke
Keyword(s):  
Egg Size ◽  
Hatching Success ◽  
Size Variation ◽  
Hudson Bay ◽  
Somateria Mollissima ◽  
Physiological Mechanisms ◽  
Common Eiders ◽  
Laying Sequence ◽  
The Common ◽  
Nutrient Reserves

Intraclutch egg-size variation and hatching success were studied in a population of Hudson Bay common eiders (Somateria mollissima sedentaria) at La Pérouse Bay, Manitoba (58°24′N, 94°24′W), to test the hypothesis that females allocate more nutrient reserves to eggs that are more likely to hatch. Egg volumes were calculated for 575 known-sequence eggs in 134 complete clutches of 3–6 eggs. In general, the length of eggs decreased linearly with position in the laying sequence, whereas the breadth of eggs followed a curvilinear pattern, the second or third egg being the widest. For all clutch sizes, the last-laid egg was the smallest and the second- or third-laid egg the largest. Hatching success also varied with position in the laying sequence. Pre-incubation failure declined over the laying sequence, whereas hatching failure (dead, infertile, or rotten eggs) increased. In all cases pre-incubation failure was the major cause of egg loss (84% of total loss). Overall, third and fourth eggs were the most successful and first eggs were the least successful. With one exception, successful and unsuccessful eggs were the same size within a laying sequence. We conclude that there is no clear relationship between egg size and hatching success, and that laying sequence per se has a greater effect on hatching success. Female eiders do not appear to allocate more reserves to eggs that are most likely to hatch, and we consider other proximate, physiological mechanisms to explain the observed pattern of intraclutch egg-size variation.

scholarly journals Nest cover and faecal glucocorticoid metabolites are linked to hatching success and telomere length in breeding Common Eiders (Somateria mollissima)

2017 ◽  
Vol 95 (9) ◽  
pp. 695-703 ◽  
Author(s):  
K. Noreikiene ◽  
M. Öst ◽  
M.W. Seltmann ◽  
W. Boner ◽  
P. Monaghan ◽  
...  
Keyword(s):  
Telomere Length ◽  
Hatching Success ◽  
Prolonged Exposure ◽  
Somateria Mollissima ◽  
Faecal Glucocorticoid Metabolites ◽  
Common Eiders ◽  
Nesting Sites ◽  
Escape Responses ◽  
The Relationship ◽  
Perceived Predation Risk

Habitat-associated crypsis may affect perceived predation vulnerability, selecting for different predator avoidance strategies. Glucocorticoids could mediate the adjustment of escape responses to the extent of crypsis, introducing an overlooked source of variation in glucocorticoid–fitness relationships. However, prolonged exposure to elevated glucocorticoids may be costly, leading to accelerated telomere loss and, consequently, senescence. Here, we examined how nest cover and immunoreactive faecal glucocorticoid metabolite (fGCM) levels are linked to hatching success and telomere length in breeding female Common Eiders (Somateria mollissima (L., 1758)). We hypothesized that the degree of nest crypsis, reflecting differences in perceived predation risk, would moderate the relationship between reproductive success and fGCM levels. We also expected that telomere length would be shorter in birds with higher glucocorticoid concentration. Results showed that individuals with high fGCM levels had higher hatching success in nests with low cover, while low fGCM levels were more successful in well-concealed nests. We found that shorter telomeres were associated with high fGCM in nesting sites offering little cover and with low fGCM in well-concealed ones. This study provides the first evidence of habitat-dependent moderation of the relationships between stress physiology, telomere length and hatching success.

Elevated nest predation risk promotes offspring size variation in birds with prolonged parental care.

2019 ◽  
Author(s):  
Gretchen F. Wagner ◽  
Emeline Mourocq ◽  
Michael Griesser
Keyword(s):  
Predation Risk ◽  
Reproductive Cycle ◽  
Perceived Risk ◽  
Nest Predation ◽  
Bird Species ◽  
Size Variation ◽  
Egg Laying ◽  
Offspring Size ◽  
Natural Predation ◽  
Risk Spreading

Predation of offspring is the main cause of reproductive failure in many species, and the mere fear of offspring predation shapes reproductive strategies. Yet, natural predation risk is ubiquitously variable and can be unpredictable. Consequently, the perceived prospect of predation early in a reproductive cycle may not reflect the actual risk to ensuing offspring. An increased variance in investment across offspring has been linked to breeding in unpredictable environments in several taxa, but has so far been overlooked as a maternal response to temporal variation in predation risk. Here, we experimentally increased the perceived risk of nest predation prior to egg-laying in seven bird species. Species with prolonged parent-offspring associations increased their intra-brood variation in egg, and subsequently offspring, size. High risk to offspring early in a reproductive cycle can favour a risk-spreading strategy particularly in species with the greatest opportunity to even out offspring quality after fledging.

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