I haven't used the bison data specifically, but other USGS data that I have used that had an interactive web site to retrieve data had very specific workflows required to retrieve the data. It was a matter of very carefully reading through all the documentation and following the instructions. There weren't any workarounds; you had to use their website, their apps, and use their workflow. After you got it all downloaded, then you can export it out and parse it to be like any other data. Since the USGS likes to be comprehensive, their data is not simple. So, expect it to take a little effort.
