Do environmental factors influence the development of the gut microbiome in young birds?

Symbiotic relationships between hosts and microbiomes are often vital to the host. E.g., gut microbes are important for host physiology and host development (e.g., gut morphology, organ development and function, and the immune system). Young animals may acquire gut microbiota via several pathways: 1) maternal transmission prior to birth, 2) transmission during birth, 3) parental transmission after birth, and 4) transmission via food and surroundings. However, since the host provides the habitat conditions for its gut microbiome, the host may influence its gut microbiome composition. In young animals this may result from variations in development and growth, which may impact phenotype. When environmental factors negatively affect young development (e.g., adverse weather and limited food), gut microbiome development may be also affected, resulting possibly in variations in adult gut microbiomes. Here we explore if and how environmental conditions affect the gut microbiome development in young birds. We investigated this in rock pigeons chicks (Columba livia) in captivity that were raised under limited food or ad libitum food conditions. And in free-living pied flycatcher chicks (Ficedula hypoleuca) that were born early or late in the breeding season, which resulted in differences in weather and potentially also in diet composition.