Adrenocortical sensitivity to stress in Dark-eyed Juncos<i>(Junco hyemalis oregonus)</i>breeding in low and high elevation habitat

Bears, Heather; Smith, James N.; Wingfield, John C.

doi:10.1080/11956860.2003.11682758

Cited by 27 publications

(26 citation statements)

References 17 publications

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“…Other studies have produced similar results (e.g. Astheimer et al, 1994;Bears et al, 2003). Therefore, if an individual experienced a stressful event, such as an attempted nest predation or an agonistic encounter (which could easily be missed by an observer due to the scale of the colony and the spatial distribution of our study sub-colonies), shortly before it was chosen for sampling, then the persistence of the corticosterone response to that stressor could confound the sample to be regarded as baseline.…”

Section: Discussionmentioning

confidence: 66%

“…Our results also suggest that the sexes should be examined separately in this species, and care should be taken to identify sex differences in studies of corticosterone in other avian species, a recommendation supported by the identification of sex differences of both basal corticosterone concentrations, and corticosterone acute responses in other bird species (Astheimer et al, 1994;Hood et al, 1998;Bears et al, 2003;Hayward et al, 2006;Wada et al, 2006). A significant sex difference was detected in plasma testosterone, but not in faecal testosterone metabolites.…”

Section: Discussionmentioning

confidence: 99%

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Comparing plasma and faecal measures of steroid hormones in Adelie penguins Pygoscelis adeliae

et al. 2009

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Abstract. Physiological measurements of both stress and sex hormones are often used to estimate the consequences of natural or human-induced change in ecological studies of various animals. Different methods of hormone measurement exist, potentially explaining variation in results across studies; methods should be cross-validated to ensure they correlate.We directly compared faecal and plasma hormone measurements for the first time in a wild free-living species, the Adelie penguin (Pygoscelis adeliae). Blood and faecal samples were simultaneously collected from individual penguins for comparison, and assayed for testosterone and corticosterone (or their metabolites). Sex differences and variability within each measure, and correlation of values across measures were compared. For both hormones, plasma samples showed greater variation than faecal samples. Males had higher mean corticosterone concentrations than females, but the difference was only statistically significant in faecal samples. Plasma testosterone, but not faecal testosterone, was significantly higher in males than females. Correlation between sample types was poor overall, and weaker in females than in males, perhaps because measures from plasma represent hormones that are both free and bound to globulins, whereas measures from faeces represent only the free portion. Faecal samples also represent a cumulative measure of hormones over time, as opposed to a plasma 'snapshot' concentration. Our data indicate that faecal sampling appears more suitable for assessing baseline hormone concentrations, while plasma sampling may best define immediate responses to environmental events. Consequently, future studies should ensure they select the most appropriate matrix and method of hormone measurement to answer their research questions.

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Section: Discussionmentioning

confidence: 66%

Section: Discussionmentioning

confidence: 99%

Comparing plasma and faecal measures of steroid hormones in Adelie penguins Pygoscelis adeliae

et al. 2009

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“…Across their range (Bears et al, 2003;Homan et al, 2003;Romero and Wikelski, 2002;Scheuerlein et al, 2001;Wilson and WingWeld, 1994;WingWeld et al, 1983) and over time (season: PerWto et al, 2002;Wada and Shimizu, 2004;age: Schwabl, 1999), vertebrates vary in their corticosteroid responses to stress. This stress response, which helps shift the phenotype of the organism into an "emergency life history" state , often leads to behavioral and physiological changes in animals (Buttemer et al, 1991;Kitaysky et al, 2001Kitaysky et al, , 2003Pravosudov et al, 2001;Wikelski et al, 1999a) that presumably promote survival of stressful events (Sapolsky, 1992;WingWeld et al, 1998).…”

Section: Introductionmentioning

confidence: 99%

Corticosterone suppresses cutaneous immune function in temperate but not tropical House Sparrows, Passer domesticus

Martin

Gilliam

Han

et al. 2005

General and Comparative Endocrinology

152

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“…Previous studies have found a negative relationship between CORT p and elevation (Bears et al. ; Pereyra and Wingfield ; Li et al. ).…”

Section: Discussionmentioning

confidence: 84%

Large‐scale spatial variation in feather corticosterone in invasive house sparrows (Passer domesticus) in Mexico is related to climate

Treen

Hobson

Marchant

et al. 2015

Ecology and Evolution

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Ecologists frequently use physiological tools to understand how organisms cope with their surroundings but rarely at macroecological scales. This study describes spatial variation in corticosterone (CORT) levels in feathers of invasive house sparrows (Passer domesticus) across their range in Mexico and evaluates CORT–climate relationships with a focus on temperature and precipitation. Samples were collected from 49 sites across Mexico. Feather CORT (CORTf) was measured using methanol-based extraction and radioimmunoassay. Relationships between CORTf and spatial and climate variables were examined using simple linear regressions. Ordination was used on climate data, CORTf was plotted against the resulting axes, and univariate regression trees were used to identify important predictors of CORTf. Universal kriging interpolation was used to illustrate spatial variation in CORTf across Mexico. Correlations with ordination axes showed that high CORTf was associated with low precipitation during the rainy season and low dry season temperatures. Specifically, CORTf was negatively related to May precipitation and January and July minimum temperatures, and positively related to April deuterium excess and June minimum temperatures. CORTf was higher in second-year birds compared to after-hatch years and after-second years. House sparrows had higher CORTf levels in the hot, dry, north-central region of Mexico, and CORTf was negatively related to temperature and precipitation. House sparrows molt primarily from August–September but climate conditions throughout the year were important predictors of CORTf, suggesting that conditions outside of molt can carry over to influence energetics during feather growth. These data suggest that dry conditions are challenging for house sparrows in Mexico, supporting previous work showing that precipitation is an important predictor of broad-scale CORT variation. This work highlights the utility of CORTf for evaluating the influence of physiology on current avian range limits; furthermore, these data may allow us to predict future changes in species distributions.

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Adrenocortical sensitivity to stress in Dark-eyed Juncos(Junco hyemalis oregonus)breeding in low and high elevation habitat

Cited by 27 publications

References 17 publications

Comparing plasma and faecal measures of steroid hormones in Adelie penguins Pygoscelis adeliae

Comparing plasma and faecal measures of steroid hormones in Adelie penguins Pygoscelis adeliae

Corticosterone suppresses cutaneous immune function in temperate but not tropical House Sparrows, Passer domesticus

Large‐scale spatial variation in feather corticosterone in invasive house sparrows (Passer domesticus) in Mexico is related to climate

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