Moselio Schaechter of Small Things Considered has authored a post about the work of Maria Dominguez-Bello of the University of Puerto Rico who has been studying Opisthocomus hoazin, a unique bird who is known to carry out a pre-gastric (ruminal) fermentation. Dominguez-Bello has been investigating the microbiome of the bird's crop, an enlarged area of the esophagus, and how it changes from infancy to adulthood.
Click source for more.