If you use tires consider using old brick, broken concrete, or large crushed limestone as filler in the tire walls and across the bottom. Then add pea gravel-coarse sand mix to the top 5"-6". Maybe initially add a couple tires filled with a couple different sizes of gravel, crushed stone, or sand. Observe which is preferred and then add remaining tires. LMB would use tractor tires with gravel as a nesting area.
Last edited by Bill Cody; 02/24/16 02:35 PM.
