Resources allocated in reproduction are traded off against those invested in self-maintenance such as antioxidant response. Glutathione (GSH) is an intracellular antioxidant defence that scavenges reactive oxygen species, the deleterious byproducts of oxygen consumption. Given the role of intracellular GSH in pheomelanogenesis, a trade-off in GSH allocation between resistance to oxidative stress and melanin production may take place. To investigate how intracellular GSH is regulated in differently coloured individuals at the time of reproduction (in adults) and of intense melanogenesis (in nestlings), we measured the total pool of GSH produced ( t GSH), consumed (oxGSH) and available (redGSH) in adult tawny owls and their offspring which were cross-fostered between randomly chosen nests. Our goal was to describe potential correlations between resistance in oxidative stress and colour morphs in natural conditions. Nestling GSH levels were correlated with GSH levels in their genetic and foster parents suggesting that producing GSH is genetically and environmentally determined (although the effect of the foster nest seemed stronger). This species shows continuous variation in phe - omelanin reddish colouration, which is associated with life-history strategies. Based on the hypothesis of GSH dependence of pheomelanism, we expected a greater amount of oxGSH in dark compared to light pheomelanic nestlings, which was not the case. In contrast, light melanic breeding adults had higher levels of t GSH and redGSH than dark breeders probably because of a higher investment in antioxidant capacity. The link between pheomelanism and GSH may therefore be due to the fact that differently colored individuals have different life-history strategies rather than because the production of pheomelanin pigments requires GSH.

See the description of the methods in the published paper.

Dataset is provided in one MS Excel dataset with 3 tabs:

1. Data collected on chicks (GSH JUV)

2. Data collected on adults (GSH AD)

3. Metadata providing a description of the different column headers of GSH JUV and GSH AD

The nest-box ID and/or Ring ID can be used to merge the data on adults with the data on chicks to replicate the analyses presented in the article.