ORIGINAL: Pepito
Sometimes these taildragger models are designed with a ground attitude that is too high for their own good. If you combine that with a pilot that likes to land REALLy slow you get a situation where the plane is landing at a post stall ( or very high) angle of attack. After the model touches down, it instantaneoulsly transitions to horizontal translation (the ground forces it to) and the ground attitude becomes the new angle of attack which is now a very high but pre-stall angle of attack, and the wing's lift now is higher than before touch down! The model takes off again, goes into stall, touches down, takes off, etc., etc.
Taildragger aircraft make bouncing landings because they do not have the nose high enough when the main wheels touch down. For a given speed, increasing the angle of attack of the wing will increase lift, as long as the angle is below the stalling angle. When a taildragger is a bit fast, the mains will touch first. This causes an "up" force upon the aircraft forward of the CG. The nose is pitched upwards, increasing the angle of attack. The aircraft "balloons" into the air. It can then stall and pitch down dramatically. If the speed is high enough at the next touchdown, then the process repeats. Many times, though, the model winds up on its nose after one or two repeats of the bouncing.
If the stall angle is high enough, a taildragger can actually touch tailwheel first. This results in a landing that "sticks". That's because for the speed, when you touch tail first, the wing's angle of attack is reduced, and so lift is reduced. The model cannot bounce back into the air...regardless of the actual touchdown speed.
Lowering lift when you reduce angle of attack on landing is why a "stuck" landing happens when tricycle-geared airplanes touch mainwheels first and then lower the nosewheel to the ground. Lift is reduced. Works well for full-size aircraft. If the model is set up so that it's slightly nose-low on the ground, landings will be easy to make without bouncing.
An excellent reference about how airplanes fly (full-size or models) is the book "Stick and Rudder" by Wolfgang Langeweische. A classic book that describes flight from the pilot's viewpoint. It about full-size aircraft, but the principles all apply to models as well.