Obtaining plasma to measure baseline corticosterone concentrations in reptiles: How quick is quick enough?

Comparing baseline and stress-induced glucocorticoid hormone levels in animals is a popular tool to assess differences in stress experienced among groups. We compare corticosterone levels in Magellanic Penguins (Spheniscus magellanicus (J.R. Forster, 1781)) in situations where we hypothesize differences in stress patterns may exist. We compared penguins both within and between breeding seasons, birds breeding at two different locations, penguins at three different ages, penguins that had shown evidence of recent fighting, and, finally, how stress patterns differed for four different penguin species. Throughout a breeding season (settlement, incubation, and chick-rearing), we found no differences in either baseline or stress-induced hormone concentrations. Chick, juvenile, and adult penguins did not differ in baseline corticosterone levels, but juveniles had a reduced stress response. Penguins in one season showed a stress response to capture, likely due to a recent severe weather event. We found no differences in baseline or stress-induced hormone titers for birds from two different breeding locations. Evidence of recent fighting also did not alter baseline corticosterone levels. Finally, among four species of penguins measured (Magellanic, Humboldt (Spheniscus humboldti Meyen, 1834), Galápagos (Spheniscus mendiculus Sundevall, 1871), and Rockhopper (Eudyptes chrysocome (J.R. Forster, 1781)), baseline levels were always consistent, while stress-induced levels were significantly higher in the Rockhopper Penguin only.

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The relationship of telomere length to baseline corticosterone levels in nestlings of an altricial passerine bird in natural populations

Frontiers in Zoology ◽

10.1186/s12983-016-0133-5 ◽

2016 ◽

Vol 13 (1) ◽

Cited By ~ 34

Author(s):

Verónica Quirici ◽

Claudia Jimena Guerrero ◽

Jesse S. Krause ◽

John C. Wingfield ◽

Rodrigo A. Vásquez

Keyword(s):

Telomere Length ◽

Natural Populations ◽

Passerine Bird ◽

Baseline Corticosterone ◽

Relationship Of ◽

The Relationship

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Early-life maltreatment predicts adult stress response in a long-lived wild bird

Biology Letters ◽

10.1098/rsbl.2017.0679 ◽

2018 ◽

Vol 14 (1) ◽

pp. 20170679 ◽

Cited By ~ 9

Author(s):

Jacquelyn K. Grace ◽

David J. Anderson

Keyword(s):

Life Stress ◽

Early Life ◽

Early Life Stress ◽

Nutritional Stress ◽

Free Living ◽

Corticosterone Concentration ◽

Sula Granti ◽

Adaptive Mechanisms ◽

Baseline Corticosterone

Persistent phenotypic changes due to early-life stressors are widely acknowledged, but their relevance for wild, free-living animals is poorly understood. We evaluated effects of two natural stressors experienced when young (maltreatment by adults and nutritional stress) on stress physiology in wild Nazca boobies ( Sula granti ) 6–8 years later, an exceptionally long interval for such studies. Maltreatment as a nestling, but not nutritional stress, was associated years later with depressed baseline corticosterone in females and elevated stress-induced corticosterone concentration [CORT] in males. These results provide rare evidence of long-term hormonal effects of natural early-life stress, which may be adaptive mechanisms for dealing with future stressors.

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Genetic inheritance and environment determine endocrine plasticity to urban living

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2019.1215 ◽

2019 ◽

Vol 286 (1908) ◽

pp. 20191215 ◽

Cited By ~ 4

Author(s):

Jenny Q. Ouyang ◽

Davide Baldan ◽

Crystal Munguia ◽

Scott Davies

Keyword(s):

Urban Areas ◽

Natural Populations ◽

Genetic Component ◽

Future Generations ◽

Free Living ◽

House Wren ◽

Endocrine Stress Response ◽

Baseline Corticosterone ◽

Impact Of Urbanization ◽

The Impact

As urban areas continue to expand globally, understanding how and why species respond to novel habitats becomes increasingly important. Knowledge of the mechanisms behind observed phenotypic changes in urban animals will enable us to better evaluate the impact of urbanization on current and future generations of wildlife. Physiological changes, such as those involved in the endocrine stress response, may allow individuals to inhabit and thrive in urbanized areas, but it is currently unknown how these changes arise in natural populations. In this study, we performed a four-way cross-foster experiment in free-living house wren chicks, Troglodytes aedon , to disentangle whether differences in baseline corticosterone between urban and rural individuals are a result of genetic and/or plastic mechanisms during development. We found that urban chicks already had higher corticosterone levels than their rural counterparts on the day they hatched, which suggests a possible genetic component to the corticosterone phenotype. However, rural offspring that were moved to an urban environment significantly increased their corticosterone levels, mimicking those of urban offspring. Our findings suggest that, although differences in baseline corticosterone concentrations between urban and rural individuals may have a genetic component, plasticity plays a pivotal role and can modify the corticosterone phenotype in response to the environment experienced in the first two weeks of life.

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Corticosterone and timing of migratory departure in a songbird

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2016.2300 ◽

2017 ◽

Vol 284 (1846) ◽

pp. 20162300 ◽

Cited By ~ 21

Author(s):

Cas Eikenaar ◽

Florian Müller ◽

Clara Leutgeb ◽

Sven Hessler ◽

Konstantin Lebus ◽

...

Keyword(s):

Physiological Mechanism ◽

Hormonal Control ◽

Major Step ◽

Extrinsic Factors ◽

Stopover Site ◽

High Baseline ◽

Intrinsic Factors ◽

Baseline Corticosterone ◽

Departure Decisions ◽

Time Required

Bird migration entails replenishing fuel stores at stopover sites. There, individuals make daily decisions whether to resume migration, and must also decide their time of departure. Variation in departure timing affects the total time required to complete a migratory journey, which in turn affects fitness through arrival time at the breeding and wintering grounds. It is well established that stopover departure decisions are based on cues from innate rhythms, intrinsic factors and extrinsic factors. Yet, virtually nothing is known about the physiological mechanism(s) linking these cues to departure decisions. Here, we show for a nocturnal migratory songbird, the northern wheatear ( Oenanthe oenanthe ), that baseline corticosterone levels of birds at stopover increased both over the migratory season and with wind assistance towards the migratory destination. Corticosterone in turn predicted departure probability; individuals with high baseline corticosterone levels were more likely to resume migration on a given night. Corticosterone further predicted the departure time within the night, with high baseline levels being associated with early departures. These novel findings indicate that corticosterone may be mediating between departure cues and the timing of departure from a stopover site, which is a major step towards understanding the hormonal control of animal migration.

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Repeated thermal stressor causes chronic elevation of baseline corticosterone and suppresses the physiological endocrine sensitivity to acute stressor in the cane toad (Rhinella marina)

Journal of Thermal Biology ◽

10.1016/j.jtherbio.2014.02.011 ◽

2014 ◽

Vol 41 ◽

pp. 72-76 ◽

Cited By ~ 25

Author(s):

Edward J. Narayan ◽

Jean-Marc Hero

Keyword(s):

Cane Toad ◽

Rhinella Marina ◽

Baseline Corticosterone ◽

Acute Stressor

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Baseline corticosterone does not reflect iridescent plumage traits in female tree swallows

10.1101/452029 ◽

2018 ◽

Author(s):

Keneth Sarpong ◽

Christine L. Madliger ◽

Christopher M. Harris ◽

Oliver P. Love ◽

Stéphanie M. Doucet ◽

...

Keyword(s):

Tree Swallows ◽

Secondary Sexual Traits ◽

Factors Affecting ◽

Brood Rearing ◽

Trade Offs ◽

Female Tree ◽

Baseline Corticosterone ◽

Sexual Characteristics ◽

The Relationship ◽

Secondary Sexual

AbstractThe production of high quality secondary sexual traits can be constrained by trade-offs in the allocation of energy and nutrients with other metabolic activities, and is mediated by physiological processes. In birds, the factors influencing male plumage quality have been well studied; however, factors affecting female plumage quality are poorly understood. Furthermore, it remains uncertain which physiological traits mediate the relationship between body condition and ornaments. In this three-year study of after-second-year female tree swallows (Tachycineta bicolor), we investigated (1) the relationship between baseline corticosterone near the end of the brood-rearing period (CORTBR) and feather colour characteristics (hue, saturation, brightness) the following year, and (2) the relationship between baseline corticosterone measured during incubation (CORTI) and brood rearing (CORTBR), and feather colour in the same year. To control for reproductive effort, we included reproductive parameters as covariates in all analyses. In this first study between CORT and the plumage colour characteristics of a species bearing iridescent feathers, we did not find any relationship between CORTBRand the colour of subsequently-produced feathers, nor did we find any relationship between CORTIand the colour of feathers displayed during that breeding season. If CORT levels at the end of breeding carry over to influence the immediately subsequent moult period as we expect, our results generally indicate that structural plumage quality may not be as sensitive to circulating CORT levels compared to carotenoid-based colouration. Future studies, particularly those employing experimental manipulations of CORT during moult in species with iridescent traits, are necessary to fully determine the role glucocorticoids play in mediating the quality of secondary sexual characteristics.

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Foraging in Urban Environments Increases Bactericidal Capacity in Plasma and Decreases Corticosterone Concentrations in White Ibises

Frontiers in Ecology and Evolution ◽

10.3389/fevo.2020.575980 ◽

2020 ◽

Vol 8 ◽

Author(s):

Caroline R. Cummings ◽

Nicola Y. Khan ◽

Maureen M. Murray ◽

Taylor Ellison ◽

Catharine N. Welch ◽

...

Keyword(s):

Diet Composition ◽

Urban Environments ◽

Urban Habitats ◽

Natural Habitats ◽

Eudocimus Albus ◽

Bactericidal Capacity ◽

Lower Baseline ◽

Close Proximity ◽

Baseline Corticosterone ◽

Urban Sites

As humans continue to infringe on natural habitats, more animals are exposed to urbanization and its associated challenges. It is still unclear, however, whether the movement of animals into urban habitats negatively influences the health and/or survival of those animals, however those animals often experience shifts in resource availability, diet composition, and exposure to stimuli that are new and potentially stressful. Recently, white ibises (Eudocimus albus) have become increasingly common in urban habitats where they forage in close proximity to humans and even interact with them, collecting food handouts. We hypothesized that foraging in urban habitats would negatively impact measures of health, impair innate immunity, trigger elevated concentrations of corticosterone, and depress physiological responses to stressors in white ibises. We found that plasma from birds captured from urban sites had higher bactericidal capacity against Escherichia coli than those captured in natural sites. Additionally, adults captured in urban habitats had a significantly lower baseline corticosterone concentrations during the post-breeding season, and corticosterone responses to a handling challenge were lower for birds captured from urban sites during year 2 of the study. These results indicate that exposure to urban habitats impacts ibis health, though in the opposite direction of what was predicted.

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