Synchronizing feather-based measures of corticosterone and carotenoid-dependent signals: what relationships do we expect?

  title={Synchronizing feather-based measures of corticosterone and carotenoid-dependent signals: what relationships do we expect?},
  author={Graham D. Fairhurst and Russell D. Dawson and Harry van Oort and Gary R. Bortolotti},
Carotenoids produce many of the red, orange and yellow signal traits of birds, and individuals must trade off utilizing carotenoids for physiological processes versus ornamentation. Proximate mechanisms regulating this trade-off are poorly understood, despite their importance for expression of color signals. Corticosterone (CORT) may play a significant mechanistic role in signal expression because it mobilizes energy substrates and influences foraging behavior. We used a unique feather-based… 

Pigment-specific relationships between feather corticosterone concentrations and sexual coloration

Carotenoids- and phaeomelanin-based pigmentation communicate nonequivalent information about physiological stress, with carotenoid pigmentation having the potential to signal stable differences in stress levels that could affect fitness.

Feather corticosterone levels independent of developmental immune challenges predict carotenoid-based, but not melanin-based, traits at adulthood

Results support the “quality hypothesis,” which states that variation in CORT could be positively correlated with traits reflecting individual quality under certain conditions, and also suggest that the speculum in Mallards may be able to serve as an honest signal.

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

The results generally indicate that structural plumage quality may not be as sensitive to circulating CORT levels compared to carotenoid-based colouration.

Feather‐based measures of stable isotopes and corticosterone reveal a relationship between trophic position and physiology in a pelagic seabird over a 153‐year period

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Relationship between feather corticosterone and subsequent health status and survival in wild Eurasian Sparrowhawk

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Feather steroid hormone concentrations in relation to age, sex, and molting time in a long‐distance migratory passerine

A novel method based on the precolumn chemical derivatization of hormones before liquid chromatography–tandem mass spectrometry (LC‐MS/MS) analysis is used to reveal associations between Tf and Cortf hormone concentrations and feather growth, age, and sex in feathers grown during the postbreeding and prebreeding periods in barn swallows.

Feather corticosterone levels are related to age and future body condition, but not to subsequent fitness, in a declining migratory songbird

Elevated CORT may represent a beneficial physiological response (e.g. hyperphagia prior to migration), particularly for certain life-history stages, and may mediate the condition in which individuals transition between stages.

Stress‐induced changes in color expression mediated by iridophores in a polymorphic lizard

Stress detectably impacts signal expression (luminance and patterning), which may provide information on individual condition, and is likely to be mediated, at least in part, by structural coloration produced by iridophore cells.



Physiological stress links parasites to carotenoid‐based colour signals

It is shown that parasites increase stress and reduce carotenoid‐based coloration, and that the impact of parasites on coloration was associated with changes in corticosterone, more than changes in body mass.

Carotenoid-based coloration, oxidative stress and corticosterone in common lizards

How carotenoid-based color can honestly signal individual quality in this species and how the increased redness induced by corticosterone could be a terminal investment in an environment where long-term survival prospects are poor but not when immediate survival is endangered are discussed.

Carotenoids bolster immunity during moult in a wild songbird with sexually selected plumage coloration

This study provides experimental, seasonal support for a fundamental tenet of Lozano's ‘carotenoids trade-off’ hypothesis and adds to a growing list of animal species that benefit immunologically from ingesting higher dietary carotenoid levels.

The effect of capture-and-handling stress on carotenoid-based beak coloration in zebra finches

Sex- and pigment-specific mechanisms by which stress may temporarily enhance the expression of sexual traits, but at the expense of other key fitness traits (e.g., body mass maintenance, reproduction) are highlighted.

Condition‐dependence of multiple carotenoid‐based plumage traits: an experimental study

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Experimental evidence is provided for a link between testosterone levels and immunoenhancing carotenoids that reconciles conflicting evidence for the immunosuppressive nature of androgens, provides physiological grounds for a connection between two of the main signaling systems in animals, and explains how these signaling systems can be evolutionary stable and honest.

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Feather coloration in museum specimens is related to feather corticosterone

Colorful ornaments in birds are often sexually selected signals of quality, and variation in ornament expression may be mediated by physiological stress through the secretion of corticosterone.

Experimental relationships between levels of corticosterone in plasma and feathers in a free-living bird

CORTf is best used to study the activity of the HPA axis over relatively long time frames and can be used effectively to advance avian ecology, but correlations may not always be expected.