Endocrine and epigenetic flexibility in an African starling

Although many organisms rapidly and repeatedly adjust their behaviour and physiology to cope with changing environmental conditions, it remains unclear which traits are expected to exhibit phenotypic flexibility, over what timescales, and in which environments. Here, we explore endocrine (glucocorticoid hormones) and epigenetic (DNA methylation) flexibility in superb starlings (Lamprotornis superbus), a species endemic to the savannas of East Africa but that also occurs less commonly in more arid and mesic habitats. After capturing individuals from three sites in central Kenya-desert margin, savanna bushland and forest margin-birds were housed for six months under common garden conditions in the field at the savanna site. We measured corticosterone (baseline, stress-induced) and quantified genome-wide DNA methylation at the time of initial capture, as well as after three and six months in captivity. The transition to captivity caused predictable increases in baseline-though not stress-induced-corticosterone and decreases in DNA methylation in genes related to development. After six months in captivity, baseline levels of corticosterone and most differentially methylated regions of the genome returned to pre-captive levels. Ultimately, this work shows that birds living in semi-arid environments exhibit flexible endocrine and epigenetic responses to the stress of captivity that reverse over time. This article is part of the theme issue 'Ecological epigenetics at the intersection of behaviour and life history variation in non-model animals'.