Glucocorticoids modulate gastrointestinal microbiome in a wild bird

Area of Science:

• Ecology
• Microbiology
• Animal Physiology

Background:

• The gut microbiome is vital for animal health.
• Stress, through glucocorticoids, may disrupt the gut microbiome.
• Its effects on wild animal microbiomes remain largely unknown.

Purpose of the Study:

• To investigate the impact of stress-induced glucocorticoid changes on the gut microbiome of wild yellow-legged gulls (Larus michahellis).

Main Methods:

• Experimentally increased basal glucocorticoid levels using corticosterone implants in gulls.
• Assessed the effects on the gastrointestinal microbiota composition.

Main Results:

• Corticosterone-implanted gulls showed underrepresentation of several bacterial taxa.
• This reduction included potentially pathogenic bacteria (Mycoplasma, Microvirga) and beneficial commensals (Firmicutes).

Conclusions:

• Glucocorticoid levels are closely linked to gut microbiome composition in natural populations.
• Stress may confer a benefit by reducing infection risk, warranting further investigation.