Canards can give huge reductions in take-off distance for delta wing aircraft. To raise the nose of a delta in order to increase angle of attack you need to deflect the elevons upwards and so move the centre of pressure forwards. However, moving the surfaces up decreases the angle of attack and so dumps lots of your lift so now you have to go faster to get enough lift to fly - so you use lots of runway. With canards you deflect them down to move the centre of pressure forwards to raise the nose and so you actually get a small lift bonus from the canards but the real saving is that the main delta wing stays at an efficient, positive angle of attack. The same sort of argument helps with the landing as well - giving a slower touchdown speed but the biggest effect is take-off ground roll. In fighter aircraft, like the Kfir, the canards also help with manoeuvrability as you can pitch up without dumping lift with the elevons.