The Leaf above me is right, immigrants are actually usually a cut above the natives that stayed put. 
The people who get up and leave a country are usually more intelligent and have greater resources than those who choose to stay put and fuck around. This has been true forever, really. 

It's true in the sense that "humanity began in africa" and the smart ones left africa to travel to other continents, leaving the retarded niggers on africa. 
It's also true in the sense that the europeans that left europe were looking for a better life out the war and shit, and took the initiative to do so, and became pioneers. 

And it's still true with all the wetbacks crossing the border, risking their lives for a better outcome, rather than staying put comfortably in the favelas. 

You could compare those groups of "immigrants" to each other, but looking at each one relative to their native homestead-staying counterparts, they're smarter, on average. When you MOVE you take on risk and uncertainty. Low IQ people generally don't do that. It takes initiative and foresight.