Data story
Which US state has the most bird species for its size?
Delaware has the most bird species for its size: 432 species on its official list, on 1,949 square miles of land, or 221.7 species per 1,000 square miles. That is 2.4 times the figure for Connecticut, in second place (93.8). Alaska comes last, with 551 species on 571,409 square miles (1.0 per 1,000).
Counting the District of Columbia, a city of 61 square miles with 348 species, the District comes first by far (5,693.0 per 1,000 square miles), but a tiny area inflates the ratio, so we rank it apart.
- 221.7species per 1,000 square miles in Delaware, the most of any state
- 48states ranked: every state whose official list gives a total
- 44thCalifornia's place for its size (tied), though its list is the longest (696)
- 1.0species per 1,000 square miles in Alaska, the fewest
Published . Species from each state’s official bird list, read October 2 to 21, 2026; land area from the US Census Bureau, read October 21, 2026. Jump to every state, or download the data.
The 15 states with the most species for their size
Bird species on each state's official list for every 1,000 square miles of its land. Delaware's bar is more than twice as long as any other.
Every state, ranked
Highest first. A state’s name opens its page, with what its count includes and where its official list lives. Lists dated more than a year ago, or with no date, are marked: see how we counted.
| Rank | State | Per 1,000 sq mi | Species | Land, sq mi | List’s date |
|---|---|---|---|---|---|
| 1 | Delaware | Per 1,000 sq mi 221.7 | Species 432 | Land, sq mi 1,949 | List’s date July 2025 Older than a year |
| 2 | Connecticut | Per 1,000 sq mi 93.8 | Species 454 | Land, sq mi 4,843 | List’s date September 17, 2026 |
| 3 | New Jersey | Per 1,000 sq mi 69.2 | Species 509 | Land, sq mi 7,355 | List’s date September 2026 |
| 4 | Massachusetts | Per 1,000 sq mi 67.2 | Species 524 | Land, sq mi 7,801 | List’s date January 2026 |
| 5 | Hawaii | Per 1,000 sq mi 55.3 | Species 355 | Land, sq mi 6,423 | List’s date 2024 Older than a year |
| 6 | New Hampshire | Per 1,000 sq mi 47.8 | Species 428 | Land, sq mi 8,954 | List’s date February 28, 2023 Older than a year |
| 7 | Maryland | Per 1,000 sq mi 47.7 | Species 463 | Land, sq mi 9,711 | List’s date October 2, 2024 Older than a year |
| 8 | Vermont | Per 1,000 sq mi 43.2 | Species 398 | Land, sq mi 9,217 | List’s date August 26, 2025 Older than a year |
| 9 | Maine | Per 1,000 sq mi 15.4 | Species 475 | Land, sq mi 30,845 | List’s date September 13, 2025 Older than a year |
| 10 | South Carolina | Per 1,000 sq mi 15.1 | Species 453 | Land, sq mi 30,064 | List’s date 2023 annual report Older than a year |
| 11 | West Virginia | Per 1,000 sq mi 14.8 | Species 357 | Land, sq mi 24,041 | List’s date May 28, 2025 Older than a year |
| 12 | Virginia | Per 1,000 sq mi 12.5 | Species 494 | Land, sq mi 39,481 | List’s date December 2025 |
| 13 | Indiana | Per 1,000 sq mi 11.7 | Species 420 | Land, sq mi 35,825 | List’s date August 2013 Older than a year |
| 14 | Louisiana | Per 1,000 sq mi 11.4 | Species 493 | Land, sq mi 43,221 | List’s date no date on the list No date |
| 15 | Ohio | Per 1,000 sq mi 11.2 | Species 456 | Land, sq mi 40,859 | List’s date July 2026 |
| 16 | New York | Per 1,000 sq mi 11.0 | Species 518 | Land, sq mi 47,123 | List’s date May 22, 2026 |
| 17 | Tennessee | Per 1,000 sq mi 10.5 | Species 434 | Land, sq mi 41,225 | List’s date December 2024 Older than a year |
| 18 | Florida | Per 1,000 sq mi 10.2 | Species 545 | Land, sq mi 53,658 | List’s date July 2024 Older than a year |
| 19 | Kentucky | Per 1,000 sq mi 10.1 | Species 400 | Land, sq mi 39,486 | List’s date January 2025 Older than a year |
| tied for 20 | North Carolina | Per 1,000 sq mi 10.0 | Species 488 | Land, sq mi 48,624 | List’s date 2023 annual report Older than a year |
| tied for 20 | Pennsylvania | Per 1,000 sq mi 10.0 | Species 448 | Land, sq mi 44,742 | List’s date 7th edition, 2024 Older than a year |
| 22 | Mississippi | Per 1,000 sq mi 9.1 | Species 429 | Land, sq mi 46,925 | List’s date June 2022 Older than a year |
| 23 | Alabama | Per 1,000 sq mi 9.0 | Species 455 | Land, sq mi 50,652 | List’s date September 2025 Older than a year |
| 24 | Wisconsin | Per 1,000 sq mi 8.4 | Species 457 | Land, sq mi 54,168 | List’s date March 23, 2025 Older than a year |
| 25 | Illinois | Per 1,000 sq mi 8.3 | Species 463 | Land, sq mi 55,514 | List’s date August 2026 |
| tied for 26 | Arkansas | Per 1,000 sq mi 8.2 | Species 428 | Land, sq mi 51,992 | List’s date no date on the list No date |
| tied for 26 | Michigan | Per 1,000 sq mi 8.2 | Species 466 | Land, sq mi 56,613 | List’s date July 7, 2025 Older than a year |
| 28 | Washington | Per 1,000 sq mi 8.0 | Species 529 | Land, sq mi 66,457 | List’s date November 2025 |
| 29 | Iowa | Per 1,000 sq mi 7.7 | Species 432 | Land, sq mi 55,854 | List’s date no date on the list No date |
| 30 | Georgia | Per 1,000 sq mi 7.4 | Species 426 | Land, sq mi 57,718 | List’s date 2023 Older than a year |
| 31 | Oklahoma | Per 1,000 sq mi 7.1 | Species 488 | Land, sq mi 68,597 | List’s date May 2022 Older than a year |
| 32 | Missouri | Per 1,000 sq mi 6.5 | Species 445 | Land, sq mi 68,747 | List’s date no date on the list No date |
| 33 | Nebraska | Per 1,000 sq mi 6.1 | Species 472 | Land, sq mi 76,815 | List’s date no date on the list No date |
| tied for 34 | Kansas | Per 1,000 sq mi 6.0 | Species 492 | Land, sq mi 81,759 | List’s date March 31, 2026 |
| tied for 34 | North Dakota | Per 1,000 sq mi 6.0 | Species 417 | Land, sq mi 68,994 | List’s date no date on the list No date |
| tied for 36 | Oregon | Per 1,000 sq mi 5.8 | Species 554 | Land, sq mi 95,997 | List’s date September 2026 |
| tied for 36 | South Dakota | Per 1,000 sq mi 5.8 | Species 440 | Land, sq mi 75,809 | List’s date no date on the list No date |
| 38 | Minnesota | Per 1,000 sq mi 5.7 | Species 454 | Land, sq mi 79,632 | List’s date no date on the list No date |
| 39 | Utah | Per 1,000 sq mi 5.6 | Species 465 | Land, sq mi 82,596 | List’s date February 2026 |
| 40 | Idaho | Per 1,000 sq mi 5.2 | Species 432 | Land, sq mi 82,645 | List’s date 2020 Older than a year |
| tied for 41 | Arizona | Per 1,000 sq mi 5.0 | Species 569 | Land, sq mi 113,656 | List’s date January 2024 Older than a year |
| tied for 41 | Colorado | Per 1,000 sq mi 5.0 | Species 522 | Land, sq mi 103,637 | List’s date kept up to date online |
| 43 | New Mexico | Per 1,000 sq mi 4.6 | Species 559 | Land, sq mi 121,313 | List’s date March 1, 2026 |
| tied for 44 | California | Per 1,000 sq mi 4.5 | Species 696 | Land, sq mi 155,860 | List’s date October 20, 2026 |
| tied for 44 | Nevada | Per 1,000 sq mi 4.5 | Species 496 | Land, sq mi 109,860 | List’s date May 6, 2025 Older than a year |
| 46 | Montana | Per 1,000 sq mi 3.1 | Species 451 | Land, sq mi 145,550 | List’s date September 25, 2026 |
| 47 | Texas | Per 1,000 sq mi 2.6 | Species 678 | Land, sq mi 261,259 | List’s date June 7, 2026 |
| 48 | Alaska | Per 1,000 sq mi 1.0 | Species 551 | Land, sq mi 571,409 | List’s date January 1, 2026 |
| Not ranked | District of Columbia Set apart: a city, not a state. | Per 1,000 sq mi 5,693.0 | Species 348 | Land, sq mi 61 | List’s date October 2, 2024 Older than a year |
| Not ranked | Rhode Island Not ranked: no verified total. | Per 1,000 sq mi – | Species – | Land, sq mi 1,034 | |
| Not ranked | Wyoming Not ranked: no verified total. | Per 1,000 sq mi – | Species – | Land, sq mi 97,089 |
“=” after a rank: tied with another state on the same rounded value.
Which state has the most bird species?
California, with 696 species on its official list (October 20, 2026), then Texas with 678 and Arizona with 569. Those are plain counts. For its size, California comes tied for 44th of 48 and Texas 47th, since both are among the three biggest states. The ten longest lists are below, each with its place both ways.
| Rank | State | Species | For its size |
|---|---|---|---|
| 1 | California | Species 696 | For its size tied for 44th (4.5 per 1,000 sq mi) |
| 2 | Texas | Species 678 | For its size 47th (2.6 per 1,000 sq mi) |
| 3 | Arizona | Species 569 | For its size tied for 41st (5.0 per 1,000 sq mi) |
| 4 | New Mexico | Species 559 | For its size 43rd (4.6 per 1,000 sq mi) |
| 5 | Oregon | Species 554 | For its size tied for 36th (5.8 per 1,000 sq mi) |
| 6 | Alaska | Species 551 | For its size 48th (1.0 per 1,000 sq mi) |
| 7 | Florida | Species 545 | For its size 18th (10.2 per 1,000 sq mi) |
| 8 | Washington | Species 529 | For its size 28th (8.0 per 1,000 sq mi) |
| 9 | Massachusetts | Species 524 | For its size 4th (67.2 per 1,000 sq mi) |
| 10 | Colorado | Species 522 | For its size tied for 41st (5.0 per 1,000 sq mi) |
How many bird species are in Alaska, Texas and California?
Alaska has 551 species on its official list (January 1, 2026), Texas 678 (June 7, 2026) and California 696 (October 20, 2026). They are the three biggest states by land, and for their size they come 48th, 47th and tied for 44th of 48: 1.0 species per 1,000 square miles in Alaska, 2.6 in Texas and 4.5 in California.
Alaska alone has 293 times Delaware's land, but its list is only 119 species longer.
Which state has the fewest bird species?
Hawaii has the shortest list of the 48 states with an official total: 355 species (2024). For its size, Alaska has the fewest: 551 species on 571,409 square miles of land, 1.0 per 1,000 square miles. Hawaii comes 5th for its size.
Why do small states have so many bird species for their size?
Because a state's list grows much more slowly than its size. The longest state list, California's 696, is less than twice the shortest, Hawaii's 355, while Alaska has 293 times the land of Delaware. So dividing by area mostly rewards being small: Delaware's 432 species are as many as Idaho's, a state 42 times its size.
What makes a list long, by the sources’ own accounts:
- Migration stops. Birds don't need land to reach a state, only a reason to stop. As many as 30 species of shorebirds visit Delaware Bay in May, the Delaware natural resources department says, most of them Red Knots, Ruddy Turnstones, Semipalmated Sandpipers, Sanderlings and Dunlins, and they depend on the eggs of horseshoe crabs during the stopover.
- Coasts collect strays. A single lost bird, once a records committee accepts it, adds a species for good. On June 24, 2021, an Ancient Murrelet, a seabird that nests in Alaska, turned up at Slaughter Beach on Delaware Bay; Delaware's committee accepted it. Strays are a large share of the long lists too: the Texas wildlife department's checklist booklet rated about 21 percent of the state's species as vagrants, and California's biodiversity atlas counts about a third of its native birds as vagrants.
- Borders and flyways. A state on the way to somewhere gets more visitors. Texas Parks and Wildlife's 2005 migration booklet puts Texas in the center of the Central Flyway and counts 333 of the 338 Nearctic-Neotropical migrants of North America north of Mexico, birds that nest in the US and Canada and winter in Central and South America, as recorded there. Mexico is next door, too: two of the Texas committee's recent firsts wintered in the far south, a Bat Falcon at Santa Ana National Wildlife Refuge in 2021-22 (report for 2022) and a Gray-collared Becard at Resaca de la Palma State Park in 2023-24 (report for 2024).
- Height and habitat. California's wildlife agency credits the state's large size, varied topography, mild climate and habitat diversity for having more bird diversity than any other state, with birds living everywhere from the top of Mount Whitney to the bottom of Death Valley (Atlas of the Biodiversity of California).
These are reasons the sources give for long lists; the ranking can't say how much each one adds in any state, since the lists don't sort their species by why they are there. What the numbers do show is the pattern: the top four, Delaware, Connecticut, New Jersey and Massachusetts, are all among the six smallest states and all on the Atlantic coast; the bottom three, Montana, Texas and Alaska, are all among the four biggest.
Which states aren't ranked, and what about DC?
Rhode Island and Wyoming aren't ranked, because none of their official lists gives a verified total (Rhode Island: the committee publishes reports on rare records, not a full list, and the only full list we found, RIBird.org's of November 2020, names no publisher or committee approval; Wyoming: the committee's only public list is a PDF made in May 2020, which gives no total and lacks species the committee has accepted since). We count a list's species ourselves only when the list is the society's own complete checklist, as with Georgia's 426; a list we know is missing species, or that no committee stands behind, stays unranked.
Rhode Island matters most: it is the smallest state, with 1,034 square miles of land, so a list of 230 species or more would put it first. The shortest list of any ranked state, Hawaii's, has 355.
The other one is big: to reach even the top five (Hawaii, 55.3), Wyoming would need 5,365 species, far more than the longest list of any state (California, 696).
The District of Columbia has 348 species on 61 square miles of land: 5,693.0 per 1,000 square miles, about 26 times the figure for Delaware. A city that size can't be compared fairly with states, so the table ranks it apart. Counting it, the top five are DC, Delaware, Connecticut, New Jersey and Massachusetts; without it, Delaware, Connecticut, New Jersey, Massachusetts and Hawaii.
One more caution: Hawaii's list covers Midway Atoll too, which isn't part of the state, and 15 of its species were seen only there. Without them, Hawaii would have 52.9 species per 1,000 square miles and still come 5th.
Free data: use it, cite it
Download every state as a CSV file (14 KB): rank, species, land area, species per 1,000 square miles, the list’s date, who keeps it and a link to it.
Free to use, share and adapt, with a link to this page as credit: the table is licensed CC BY 4.0. The species counts are each records committee's own, and the land areas are the US Census Bureau's; please name them too.
How to cite this:
Birdfolio, “Which US state has the most bird species for its size?,” October 21, 2026, https://mybirdfolio.com/bird-species-per-square-mile-by-state. Data: https://mybirdfolio.com/downloads/bird-species-per-square-mile-by-state.csv. Species: each state's official bird list; land area: US Census Bureau, 2020 Census.
How we counted
Species: the total on each state's official bird list, the one its bird records committee keeps (or the society that keeps the official list), as on our page of bird species by state, read on each official list on October 2, 2026 (Georgia and North Dakota on October 21, 2026). Each list follows its own rules: some include extinct or introduced species, some only species backed by a photo, specimen or recording. Never a field guide's estimate or an app's sightings. Georgia's 426 is our own count of the species on its checklist, which gives no total; the table's note says so.
Land area: the US Census Bureau's land area for each state from the 2020 Census, read on October 21, 2026: land only, without lakes, rivers, bays or coastal water, converted from square meters to square miles (one square mile is 2,589,988.110336 square meters).
The ratio: species ÷ square miles of land × 1,000, rounded to one decimal. States with the same rounded value share a place. 48 states are ranked; the District of Columbia is set apart and the 2 states without an official total are listed but not ranked.
Old lists: 24 of the 49 lists are dated more than a year before October 21, 2026, and 8 carry no date; the table marks them. Lists mostly grow as committees accept new species (a lump of two species into one, or a record taken off, can shorten one), so an old list may be a few species out. Delaware's own list is from July 2025, more than a year old, but its lead doesn't hang on a few species: it would stay first with as few as 183.
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