Optimum Hole Sizes (Inches) for Common Birdhouse Nesting Species

  • Chickadees, bluebirds, nuthatches, prothonotary warblers, swallows, titmice, wrens, downy woodpeckers and hairy woodpeckers prefer a hole close to  1 1/8 inches - 1 1/4"
  • Great-crested flycatchers prefer a 1 3/4-inch hole.
  • House finches, red-bellied woodpeckers and red-headed woodpeckers need a 2-inch hole.
  • Northern flickers prefer 2 1/2 inch hole.
  • Purple Martins prefer a 2 1/4-inch hole.
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