A study led by FAU’s Rindy Anderson provides the first-ever description of the relationship between a wild bird’s microbiome and its ornamentation and body condition. The team sampled the cloacal microbiomes of Northern cardinals and measured body condition, assessed coloration of sexual ornaments (beak and plumage), and collected blood to estimate glucocorticoid response to stress.

They found that the birds’ gut microbiome diversity can be predicted by its body condition and the quality of its ornamentation. Low microbiome diversity can lead to immune issues and poor nutrient absorption; high diversity can boost resilience to stress and pathogens. “Our findings confirm the hypothesis that a wild bird’s health is tied to its microbiome, and that the ‘sexiness’ of a male’s ornaments can signal his health,” says Anderson.

• Rindy Anderson