One of the ways we work to reduce the squirrel population around our pecan grove is to set traps. We use #110 conibear traps (photo at right) mounted on small shelves constructed from 2 by 4 lumber and attached to tree trunks.
Deck screws are used to attach the 2 x 4 shelf to the trunk of the tree. Mounting the trap on a shelf seems to limit the type of animals caught by the trap to squirrels.
Notice that we have driven 4 roofing nails into shelf to hold the trap in position. To position the nails on the board, draw 2 lines across the 2 x 4 near the center of the board. The lines should be 3/4 inch apart. Hammer 2 nails on each line about 1 1/4 inches apart. The large heads of the nails are what actually holds the trap in place.
When setting the trap, hold the trap open and place over the nails. Squeeze the trap tightly against the nails then set the trap catch. Note that we use pecans to bait the trap but several types of nuts will work. Make sure to bait the trap before setting it ( I don't want to hear about broken fingers!).
Ouch!