Animals host complex microbial communities, known collectively as their “microbiome", that not only affect their health but also interact strongly with their growth and development. The microbiome greatly increases in complexity after birth, therefore, the acquisition of new microbes must be a key event for newborn animals. For birds, nests are the initial environment that chicks encounter after hatching and could be important sources for their developing microbiome. In order to know if different nest types harbor different microbiomes, we sampled 37 nests from 21 species in 14 families of tropical birds in southern Mexico. Three different nest types were included: cup, basket and cavity nests. The effect of nest architecture on the nest microbiome is addressed by linking temperature and humidity data with microbial abundances from each nest. We predict that different nest types provide different environmental conditions; e.g. cup nests are more exposed than basket or cavity nests, and this gradient will affect the microbial communities inside the nest.
Results/Conclusions
We found that the internal climate of basket and cavity nests was more stable than in cup nests. The microclimate inside cup nests reached higher and lower temperatures than basket or cavity nests, with a higher daily variation in humidity levels. Such conditions resembled the external climate. However, bacterial abundances were not significantly different between nest types, suggesting that bacteria colonize nests at similar rates. Even with no differences in bacterial abundances, community composition could differ. Next Generation Sequencing will be used to compare bacterial communities between nest types. We predict that even though microbial colonization rates are similar inside different nest types, microbial species will have different specific growth requirements which in turn will modify community composition. Therefore, chicks born in different nest types will experience different microbial conditions, making the nest type itself a strong factor determining early and potentially long term bacterial associations.