why do people who are for the wall along the Souther border focus so much on S. America when a majority of illegal immigrants are from Canada?

https://www.google.com/amp/s/nationalpost.com/news/world/northern-aliens-around-100000-canadians-live-under-the-radar-in-u-s-as-illegal-immigrants/amp

Is it because of xenophobia that these border wall supporters have for people of brown skin who speak Spanish?