DOI: 10.5061/dryad.v4bf803
title: Data from: Feather steroid hormone concentrations in relation to age, sex, and moulting time in a long distance migratory passerine

description: In birds, concentrations of testosterone (T) and corticosterone (Cort) are
 closely connected with many morphological, behavioural and other
 physiological traits, including reproduction, metabolism, immunity, and
 fitness. The direction of the effect of these hormones on above-mentioned
 traits, and the potential feedback between hormones are in general
 unclear; in addition, knowledge on how age and sex can affect T and Cort
 concentrations is still inconsistent. Our study used a novel method to
 analyse testosterone and corticosterone in feathers (Tf, Cortf) based on
 the pre-column chemical derivatization of hormones before LC-MS/MS
 analysis. Unlike previously used methods (RIA, EIA), our analytical
 procedure allows simultaneous analysis of both hormones from small amounts
 of feathers (4-25 mg) and thus overcomes the problem of insufficient
 detection limits. We applied this method to reveal associations between Tf
 and Cortf hormone concentrations and feather growth, age, and sex in
 feathers grown during the post-breeding (flanks) and pre-breeding (tails)
 periods in barn swallows (Hirundo rustica). There was neither a
 correlation between pre-breeding and post-breeding Tf, nor between
 pre-breeding and post-breeding Cortf. Tail Cortf concentrations were
 negatively associated with tail feather growth rates. Feather hormone
 concentrations were correlated in the pre-breeding period, negatively in
 males but positively in females. Both Cortf and Tf were higher in young
 birds compared to older ones, indicating either an age-related decrease in
 hormone concentrations within individuals, or the selective disappearance
 of individuals with high steroid concentrations. Males and females did not
 differ in Cortf, but Tf concentrations were higher in males than females,
 particularly during the pre-breeding period. In this study, we provide an
 effective method for analysing hormones in feathers in an ecological
 context, especially in situations when the total amount of feathers
 available for the analysis is limited.
description: data_Adamkova_et_alIn birds, concentrations of testosterone (T) and corticosterone (Cort) are closely connected with many morphological, behavioural and other physiological traits, including reproduction, metabolism, immunity, and fitness. The direction of the effect of these hormones on above-mentioned traits, and the potential feedback between hormones are in general unclear; in addition, knowledge on how age and sex can affect T and Cort concentrations is still inconsistent. Our study used a novel method to analyse testosterone and corticosterone in feathers (Tf, Cortf) based on the pre-column chemical derivatization of hormones before LC-MS/MS analysis. Unlike previously used methods (RIA, EIA), our analytical procedure allows simultaneous analysis of both hormones from small amounts of feathers (4-25 mg) and thus overcomes the problem of insufficient detection limits. We applied this method to reveal associations between Tf and Cortf hormone concentrations and feather growth, age, and sex in feathers grown during the post-breeding (flanks) and pre-breeding (tails) periods in barn swallows (Hirundo rustica). There was neither a correlation between pre-breeding and post-breeding Tf, nor between pre-breeding and post-breeding Cortf. Tail Cortf concentrations were negatively associated with tail feather growth rates. Feather hormone concentrations were correlated in the pre-breeding period, negatively in males but positively in females. Both Cortf and Tf were higher in young birds compared to older ones, indicating either an age-related decrease in hormone concentrations within individuals, or the selective disappearance of individuals with high steroid concentrations. Males and females did not differ in Cortf, but Tf concentrations were higher in males than females, particularly during the pre-breeding period. In this study, we provide an effective method for analysing hormones in feathers in an ecological context, especially in situations when the total amount of feathers available for the analysis is limited.