Robert Louis Caldwell Tall Pickings (yellow-billed oxpecker), graphite pencil, 5 x 9. ← Previous Next → Robert Louis Caldwell Tall Pickings (yellow-billed oxpecker), graphite pencil, 5 x 9. Robert Louis Caldwell, Tall Pickings (yellow-billed oxpecker), graphite pencil, 5 x 9.