Fair criticism, this is based on EPA Level III/IV Ecoregions (cited in https://github.com/olivierlacan/indigene/blob/main/DATA_SOUR...) but I agree there should be a way to see it in a clear map.

Level III/IV Maps are here: https://www.epa.gov/eco-research/level-iii-and-iv-ecoregions...

At the very least I'll make sure each region page links to this given it's the source that determines what species are shown.