A)
Pigs were first brought to the Americas in the 1500s. Some of these pigs escaped into the wild, where they established the feral pig population. Since these pigs had never existed in this region, they filled an entirely new ecological niche. Surplus of food, shelter, and habitat resulted in a huge population spike.
b)
Feral pig population is still on the rise in North America. However, their population growth has slowed. Eventually limits on their food sources and habitat will likely limit their population rise.