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More Than 30% of Variation in House Sparrows’ Hormonal Response to Food Availability Was Heritable

Male house sparrow searching for food
Research · Physiology

More than 30% of the observed variation in how strongly house sparrows (Passer domesticus) changed their glucocorticoid response when food availability shifted was estimated to be heritable. The study therefore found that hormonal plasticity — an individual’s ability to adjust its endocrine response when conditions change — contains a moderate genetic component.

Glucocorticoids are part of the hormonal system animals use when responding to environmental challenges. In birds, corticosterone is the principal glucocorticoid. The researchers were interested not simply in whether some sparrows had higher hormone levels than others, but in whether individuals differed consistently in how much their hormone levels changed between adequate and restricted food.

Parents and offspring faced the same changes in food availability

The parental generation experienced alternating feeding treatments twice. During restricted periods, each bird received 70% of its individual daily food intake; during adequate periods, it received 110%. Blood samples taken after each treatment showed how strongly glucocorticoid levels changed with food availability.

The researchers then selected the 20 most responsive birds, the 20 least responsive birds and 20 birds chosen at random as a control group. These birds reproduced in separate aviaries, and the offspring were later tested with the same alternating feeding treatments.

Cross-fostering helped separate inheritance from rearing environment

Some offspring were raised by foster parents, allowing the researchers to distinguish resemblance to genetic parents from effects of the parental and rearing environment. Quantitative genetic models then estimated how much of the variation in glucocorticoid plasticity could be attributed to inherited differences.

The estimated heritability exceeded 30%, which the authors describe as moderate. This does not mean that 30% of an individual bird’s hormone response is “genetic”; it means that genetic differences accounted for more than 30% of the observed variation in plasticity among the birds in this study.

Hormonal flexibility has the potential to evolve

The result provides evidence that individual differences in endocrine plasticity can be inherited. Because natural selection can act on heritable variation, the authors conclude that this flexibility has the potential to evolve, particularly in dynamic and rapidly changing environments.

Sources and image credit

  1. Ouyang, J. Q., & Lendvai, Á. Z. (2026). Hormonal plasticity to food restriction is heritable in the house sparrow, Passer domesticus. Journal of Animal Ecology, 95(4), 672–683. https://doi.org/10.1111/1365-2656.70222Primary peer-reviewed research article. First published 2 February 2026. The study estimated moderate heritability (h² > 30%) in glucocorticoid plasticity in response to food availability.

Image: Triops1972 / Wikimedia Commons — house sparrow (Passer domesticus) searching for food, photographed 18 October 2014. Illustrative photograph, not a bird from the hormonal-plasticity experiment. · CC BY-SA 4.0 — https://creativecommons.org/licenses/by-sa/4.0/ · Source

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