Purple Martins are fabulous birds. I used to have them in my yard in FL, someday I will have them again, too many trees in yard keeps them away. They need open space 30-40 feet on each side of their home because of the way they fly.
If you want to attract butterflies to your garden, be sure to include these ideas. Research the types of plants and flowers that attract butterflies but they have other needs. Provide water, supplemental food and a place to rest. You'll want to include a mud puddle. You can offer them bananas and other pieces of fruit. Some gardeners include salt blocks in their garden. Butterflies bask in the sun to warm up. Include flat rocks in the sunny spots.