Red squirrels are the hardest to combat, because they cache food indoors, and they can learn to avoid traps.

Why are squirrels avoiding my trap?

If a squirrel is only mildly interested in the bait inside the trap, they will not enter because they're aware that the trap is a foreign object. Their desire to have the bait has to override their skittishness of the trap.

Are squirrels Smart enough to avoid traps?

Whenever you need to trap them, you should not expect it to be that easy or simple. The squirrels can learn to avoid traps. They avoid traps as much as they can, which means that you will have a harder time trying to capture them.