A Havahart coon sized trap modified to catch the slyest of squirrels.
This trap uses a secondary trigger bar and a mouse trap to trigger the existing spring loaded door. The added trigger bar can be any light weight material such as a wooden dowel or as I have used, a piece of aluminum tubing similar to an automotive brake line. This bar is inserted through the trap just aft and above the existing trigger pan. A device should be placed on the ends of the bar to prevent it from being pulled too far through the trap. It is hung loosely in place using a spring on either side that allows the bar to move freely in an up and down fashion. (3/4 to 1 inch is ideal) Be sure the springs are only strong enough to lift the bar and weak enough that the lightest of squirrels can still push the bar down. Mount a mouse trap directly over the trigger bar to the top of the cage. Drill a hole through the mouse trap and through the trigger to allow for a vertical attachment from the trigger bar below. Use a stiff wire or tubing to attach to the trigger bar. Run the wire up through the mouse trap and its trigger but do not attach it to the trigger. Allow the wire to extend past the mouse trap trigger and place a short bend in it so it will not fall back through. The reason you do not want to attach the wire to the trigger is so the trigger bar and vertical attach wire can bounce and sway slightly in the wind without triggering the device. From the mouse trap bar attach a piece of rather flexible wire. This wire should be just long enough that when attached to the cages trip arm it will pull the locking mechanism out of the door when the mouse trap is sprung. In this manner the original traps trigger is not affected by the modification and still works the same as it always has. I have used this trap very successfully with only a few minor problems. First of all is that a squirrel or any other larger animal in confinement will find the things that you may need to improve or work on. For example chewing on the wires or pulling the trigger bar into the trap. The other area of concern is, you should use a plastic mouse trap as the wooden ones do not hold up well in the weather. I hope this is clear enough to understand and gives you enough information so you can use your own American ingenuity to fill in the gaps. Good Luck . .
Squirrel trap design from Reddog
Design from Stump Knocker