From the fog-drenched forests of the Great Smoky Mountains and lakeshore prairies of Indiana Dunes to the cliffs of the Grand Canyon and coral reefs of Biscayne Bay, the U.S. national parks are not just scenic getaways.
They are living museums of biological wonder. They are scientific goldmines and evolutionary laboratories. Safe havens for dozens of endangered species.
Across the system’s 85 million acres, these protected lands preserve an astonishing array of animal and plant life, sheltering ecosystems that would otherwise be fractured or lost to development.
The parks harbor threatened wildlife, rare plant communities, evolutionary oddities, and protect entire ecosystems found nowhere else on Earth.
In an era of accelerating climate disruption, increased resource extraction, and habitat loss, the biological wealth of national parks is more than a conservation triumph—it is a literal lifeline.
I spent a couple of days analyzing the National Park Service’s species database—an absolute treasure trove of meticulously recorded statistics about fauna and flora in the parks.
Let’s dive in.
A Deep Dive Into the Biodiversity of the National Parks
The National Park Service (NPS) maintains an extraordinary biological catalog: thousands of species of mammals, birds, reptiles, amphibians, fish, and vascular plants.
Some parks boast sheer abundance, while others pack staggering density into compact footprints.
A comparison of biodiversity across the nation’s national parks reveals clear standouts—both in overall species richness and in category-specific dominance.
Wildlife Biodiversity in the National Parks
The National Park Service keeps detailed records of the five classes of vertebrates in its parks: mammals, birds, reptiles, amphibians, and fish.
(Although there are thousands of species of invertebrates in the parks too, such as spiders, insects, slugs, and crabs, there are no official records of those. Therefore, they are not included here.)
Mammals
Among vertebrates, mammals often capture the imagination more than any other class.
Roosevelt elk bugling in Olympic National Park, moose munching on aquatic plants in Grand Teton, black bears rustling through Shenandoah’s hollows, orcas hunting in Glacier Bay… it’s mammals that most visitors come to see.
Across the park system, Big Bend, Yosemite, Great Smoky Mountains, Grand Canyon, and Redwood emerge as mammalian hotbeds.
California’s Redwood National Park tops the list—the only national park with more than 100 mammal species—combining dense forests with coastal ecosystems to shelter everything from mountain lions, river otters, beavers, elk, and Pacific fishers to sea lions, dolphins, whales, and harbor seals.
The Grand Canyon’s biodiversity stems from its vertical wilderness—where habitats range from dry canyon bottoms and lush riverside ecosystems to subalpine forests. This sprawling park is home to more than 90 mammal species, including bison, pronghorn, bighorn sheep, coyotes, bats, and kit foxes.
The Great Smokies, meanwhile, remain a critical sanctuary for Appalachian wildlife like white-tailed deer, flying squirrels, red foxes, and raccoons.
In Yosemite National Park, visitors may have the opportunity to see mule deer, black bears, skunks, and American pikas.
Big Bend’s 80 species include ringtails, bobcats, and a rich suite of desert mammals, many overlapping with Mexico’s Sierra Madre species.
Redwood NP – 102 species of mammals
Grand Canyon NP – 91
Great Smoky Mountains NP – 88
Yosemite NP – 83
Big Bend NP – 80
Sequoia and Kings Canyon NPs – 74
Zion NP – 72
Mesa Verde NP – 72
Crater Lake NP – 71
North Cascades NP – 70
Birds
No other class of vertebrate rivals birds in visibility and migratory diversity. They’re everywhere—on lakes, rivers, and oceans, in deserts, meadows, and mountains.
Birds are, by far, the most abundant group of fauna in the parks, and migratory flyways ensure that even smaller parks punch above their weight.
Some, like Dry Tortugas, serve as critical nesting sites. Others, like the Grand Canyon and Big Bend, support hundreds of permanent and transient species.
The Grand Canyon’s vast range of ecosystems—desert scrub, riparian zones, subalpine woodlands—makes it the park system’s avian champion. From canyon wrens, common ravens, and pinyon jays to California condors, belted kingfishers, and red-tailed hawks, it’s an absolute bird watcher’s paradise.
Big Bend’s desert-meets-mountain landscape attracts both temperate and subtropical species, while the spectacular array of bird life in Death Valley proves that, sometimes, there’s more to a place than its name suggests.
New Mexico’s Carlsbad Caverns National Park surprises with 367 species, thanks to its strategic location along popular migratory routes. And in the Everglades, roseate spoonbills, wood storks, ivory-billed woodpeckers, and snail kites underscore the park’s identity as an avian sanctuary in danger.
Grand Canyon NP – 447 species of birds
Big Bend NP – 409
Death Valley NP – 384
Carlsbad Caverns NP – 367
Everglades NP – 359
Channel Islands NP – 354
Redwood NP – 309
Indiana Dunes NP – 301
Yellowstone NP – 289
Dry Tortugas NP – 289
Reptiles
Often misunderstood, reptiles are crucial members of park ecosystems. They control rodent populations, act as prey for birds and mammals, and serve as bellwethers for climate shifts.
The highest reptile counts skew toward hotter and/or drier parks.
Texas leads the list: Big Bend National Park host a wide range of rattlesnakes, lizards, geckos, and turtles and tortoises.
In the Florida Everglades, 56 reptile species—dozens of turtle and snake species, including invasive Burmese pythons—demonstrate the fragile complexity of subtropical ecosystems. Notably, Everglades National Park is also the only place in the world where American alligators and crocodiles live side by side.
Saguaro, Joshua Tree, and the Grand Canyon—all home to sun-soaked desert habitats—follow suit, proving that arid landscapes are often the opposite of barren.
Big Bend NP – 59 species of reptiles
Everglades NP – 56
Saguaro NP – 51
Joshua Tree NP – 50
Grand Canyon NP – 48
Guadalupe Mountains NP – 47
Congaree NP – 45
Carlsbad Caverns NP – 43
Great Smoky Mountains NP – 42
Death Valley NP – 35
Amphibians
Amphibians, as sensitive bioindicators, are particularly vulnerable to climate change and pollution. Yet they thrive in the moist woodlands and cave-laden parks of the eastern U.S.
The Smokies are a global amphibian stronghold, home to more species of salamanders than anywhere else on Earth, including the giant eastern hellbender. This lush, protected biome is often dubbed the “Salamander Capital of the World.”
New River Gorge, Congaree, and Shenandoah—located in the humid Appalachian and Atlantic coastal plain zones—also support amphibian super-diversity. Mammoth Cave, with its vast underground waterways, provides habitat for rare cave-dwelling species like the blind cave salamander.
Great Smoky Mountains NP – 53 species of amphibians
New River Gorge NP & PRES – 30
Congaree NP – 29
Mammoth Cave NP – 28
Shenandoah NP – 25
Redwood NP – 20
Cuyahoga Valley NP – 20
Indiana Dunes NP – 18
Everglades NP – 17
Mount Rainier NP – 14
Fish
From the deep glacier-fed fjords of Alaska to the coral reefs of the Caribbean and the South Pacific, fish diversity reveals just how aquatic some national parks truly are.
The top slots go to tropical and subtropical marine parks. American Samoa, with its vast Pacific reef systems, supports more than 600 species of tropical fish.
Biscayne is a coral reef preserve par excellence, while Glacier Bay National Park and Preserve teems with cold-water marine life like halibut, salmon, and sturgeon.
Similar to American Samoa and Biscayne, the Virgin Islands and Dry Tortugas also protect shallow coral reef and seagrass ecosystems home to hundreds of fish species.
Additionally, the Channel Islands deserve a shout-out here because, as an island group, they have so many extraordinary species that they’re often referred to as “the Galapagos of North America.”
American Samoa NP – 608 species of fish
Biscayne NP – 567
Glacier Bay NP & PRES – 329
Virgin Islands NP – 295
Dry Tortugas NP – 281
Channel Islands NP – 258
Everglades NP – 225
Redwood NP – 190
Olympic NP – 92
Wrangell-St. Elias NP – 91
National Parks With the Highest Wildlife Biodiversity
Totaling all numbers of mammals, birds, reptiles, amphibians, and fish results in a list of national parks ranked by diversity of wildlife.
When looking at the top ten below, you’ll immediately notice that they’re all parks that either are in (sub)tropical seas, have a major river, or encompass wild coastlines.
Water, clearly, is crucial to animal life and supports the highest fauna diversity in the parks.