# Microbiota-gut-brain axis in avian parenting: gut microbiome associates with nest-construction behavior and neural gene expression in a songbird

## TL;DR

This study explores how gut bacteria in songbirds are linked to nest-building behavior and brain gene activity, suggesting a role for the gut-brain axis in parenting.

## Contribution

The study reveals novel connections between gut microbiota, brain gene expression, and sex-specific nesting behavior in birds.

## Key findings

- Female zebra finches show a distinct gut microbiota composition when building nests, with Campylobacteraceae as a dominant family.
- Gut microbiota in nesting birds is enriched in functions related to energy metabolism and essential nutrient synthesis.
- Brain gene expression in nesting regions correlates with gut microbial diversity and Lactobacillaceae abundance.

## Abstract

The gut-brain axis mediates bidirectional communication between gut and central nervous activities with gut microbiota acting as a key mediator. While recent studies have mainly focused on how gut microbiota influence non-parenting social behavior in rodents, the role of gut microbiota in parenting behavior, especially in non-model species, is largely unexplored. Nest-building behavior is an early parenting behavior critical to avian survival and evolution, offering an ideal system to examine how the microbiota-gut-brain axis shapes the emergence of parental motivation.

Using zebra finches (Taeniopygia guttata), which exhibit sexually dimorphic nest-construction behaviors, we showed strong association between these preparatory parenting behaviors and gut microbiota composition. High-throughput sequencing to gut contents revealed female-specific convergent composition of gut microbiota when entering nesting status, with Campylobacteraceae rising as the predominant family. The gut microbiome of nesting birds showed enriched functions for energy metabolism and biosynthesis of essential amino acids and vitamins, reflecting elevated energy and nutritional demands, especially in females. We also observed sex-specific correlations between nesting actions and gut microbial diversity and Lactobacillaceae abundance. Notably, expression of social and gonad-related hormone genes in nesting-associated brain regions correlated with both microbial diversity and Lactobacillaceae abundance, suggesting integrated relationships between the gut microbiome, brain gene expression and nesting behavior.

Our study integrates behavior experiments, microbiota profiles, and brain gene expression to investigate the role of gut microbiome in programming sex-specific nest construction behavior in birds. These findings suggest potential mechanisms through which the microbiota-gut-brain axis regulates parenting behaviors in avian systems, expanding our understanding of how gut microbiota influence complex behaviors across animal lineages.

The online version contains supplementary material available at 10.1186/s42523-025-00486-w.