A very fair point. I was aiming for a wide variety of collections, including some with very large and diverse collections, but also ones that are smaller with only one or two excellent exhibits. In many of these instances, facilities punched well above their weight due to having one or two exhibits amongst the best possible- this category includes facilities like Nashville and DAK for primates, Jackson for ungulates, etc.While I know that the purpose of this exercise is to rank zoos based on quality and not quantity, I do wonder if might be some "apples-to-oranges" comparisons happening here, in the sense that some of these zoos have very different collection sizes. I'm curious to know whether any weight or consideration was given to how differences in the number of exhibits affects comparing the "average" or "range" in a ranking like this?
For example, you have Jackson at #7 for ungulates, yet their most recent USDA inspection only has 6 species of ungulate (at least one of which I believe is gone now) and your post only mentions 2 exhibits. Meanwhile, Saint Louis has about 3 times that many species and most of them are in exhibits that are (IMO) aesthetically pleasing and well-suited to their species - yet you considered them outside the top 10 for having "less impressive" exhibits. I feel like being judged on only your 2 best enclosures is a low bar to clear compared to an overall average of potentially 20+ enclosures.
I had this same thought when you ranked Nashville #4 for primates, despite it only having 6 species of primate on display (and the exhibits for 2 of those - the lemurs - weren't mentioned in the post). Nashville may have a fairly high average, but how meaningful is that average compared to San Diego (ranked #7) when the latter has 4 or 5 times as many primate enclosures?
I will say another thing that hurt Saint Louis in regards to ungulates, which I probably should've clarified earlier, is that I was primarily focusing on the species which were included in this list. If the list included, say, multiple additional antelope posts, Saint Louis might have had more of a case to be made. Instead, however, it was primarily based on the "popular" species on the list: elephants, giraffes, rhinos, hippos/pygmy hippos, tapirs, camels, warthogs/river hogs, takin, bighorn sheep, zebras, bongo, bison, and native deer. Others were mentioned when relevant, but by and large STL didn't stand out above the rest if one looks beyond the fact they have a diverse collection featuring various rare species.
Ranking of large zoos is tough because it is easy for some exhibits to drag down otherwise excellent facilities. In the case of San Diego and primates, for instance, despite their various excellent monkey exhibits, their ape exhibits are not amongst the best in the country which dragged them down. Likewise with carnivorans, I *almost* left Bronx off entirely as despite their tiger and snow leopard exhibits being phenomenal, the amur leopard exhibit leaves a lot to be desired. I will also add that this was a *very* subjective ranking, and not based on any sort of mathematical formula. Of course, the other difficulty is I am ranking zoos that in many cases I haven't visited, which certainly might skew my perspective.