Gaddy Bergman’s study on the changes in gut microbes and diet in bison just came out. Here, bison diet composition was measured using trnL over the course of a year. At the same time, bacterial and archaeal composition of the gut was assessed by sequencing a portion of the 16S rRNA gene. The microbial data was complex–some 45,000+ “species” were identified. The three most abundant microbial phyla were Firmicutes (53%), Bacteroidetes (33%) and Tenericutes (4%). These groups are responsible for the breakdown of carbohydrates and proteins. There were not huge swings in these groups as the season progressed, which is both surprising and not surprising. This work is just a first foray into understanding changes in gut microbial communities as the season progresses and diets change. We still do not understand the roles of these (and finer) taxonomic groups and how they might change over time or differ across herds. When you start digging deeper, there are a lot of changes in individual taxonomic groups that we do not understand yet. With almost 50,000 microbial taxa in the gut of bison, there is a lot to learn.