Well, wild horses and burros are not on this list, complied by the USDA. So point me to a more inclusive list. I've consulted several lists of invasive mammal species in North America, and the American wild horse and burro are on none of them.
LOL, according to the Executive Order 13112 definition, MAN might well qualify as an invasive species. Certainly, MAN is "naturally aggressive." Wild horses and burros are not. They are "flight" animals, not "fight" animals -- as for instance the wild pig, which is classified as an invasive mammal species on every list I've seen.
The feral horses and burros would displace native ruminants: bison, deer, elk, caribou, etc. etc.Where is your evidence for this statement?