Conversely other species have been introduced to the area like the nutria ("Myocastor coypus") from South America, now common in the area. Feral pigs ("Sus scrofa") "constitute one of the most serious conservation threats in Texas." They prey on natural populations of invertebrates, amphibians, reptiles, ground nesting birds, and rodents and are known to play a role in the transmission of disease including brucellosis, pseudorabies, and swine fever. Their forging habits involve rooting up and disturbing soils, reducing both the numbers of individual plants and animals and the number species in any given area.