If as you say they are intelligent people, open to reason, then you should look up a few wildlife conservation sites and find factual numbers on how hunting and conservation has greatly increased the number of game and non-game animals since the early 1900's! Nearly every species of game animal has benifited from the hunters dollars and hunters conservation. Many animals were almost extinct in the early 1900's and are now at the point of over-population! It is the hunters dollars (Pittman-Robertson Act for one) that fund most conservation projects. These projects are paid for by hunters, and are enjoyed by everyone!
And as to them not being morons, many animals both game and non-game would starve if not for hunting conservation, so this is a legitimate argument for hunting!
These are just a few things that you could use, if however they are just "bleeding heart liberals" they will not listen to any facts or reason, so you might as well ignore them, and save your breath! They are not worth arguing with. And it is a wise thing, when you run into a true moron anti, to let them be the ones to say dumb things, get angry and show their true colors! Remember, many times they would like to bait a hunter into getting angry, so that we look like violent people! Good luck!