Baja’s marine and animal life is just as diverse as its plant life . More than 100 mammals inhabit the peninsula, two dozen of which are considered endemic. The extreme terrain and climate has made for some interesting adaptations. Among the list of carnivores that live in the wilderness are coyotes, mountain lions, foxes, bobcats, and raccoons. Mule deer live below 1,500 meters (5,000 ft.), while fewer white-tailed deer live in the higher elevations.
Desert bighorn sheep (borrego cimarrón) have yet to recover from excessive big-game hunting of the early 20th century. And the endangered peninsular pronghorn (berrendo) survives only in the protected preserve of the Vizcaíno Desert. Also on the endangered species list is the endemic black jackrabbit.
Before it was overhunted by Dutch, British, and American whalers in the 19th century, the gray whale inhabited the Atlantic Ocean, Baltic Sea, and North Sea, as well as the Pacific Ocean. Today it lives only in the Pacific. The object of many organized trips to Baja, gray whales migrate around 19,300 kilometers (12,000 mi) a year from the Arctic Circle, where they feed, to the shallow lagoons on the west side of Baja California, where they give birth to their calves.
Adults measure 10–15 meters (35–50 ft.) long and weigh 20–40 tons. Their skin is almost black at birth, but the growth and scarring of barnacles over the years makes them look more gray than black.
There are three lagoons along the central Pacific coast of Baja where visitors can observe the gray whales up close: Laguna Ojo de Liebre near Guerrero Negro , Laguna San Ignacio , and Bahía Magdalena .
Besides the social gray whale, Baja’s Pacific and Gulf waters host two dozen species of whales and dolphins, including the endangered vaquita dolphin, which once thrived in the northern Sea of Cortez near San Felipe .
The elephant seal and Guadalupe fur seal have made a recent comeback on Isla Guadalupe and nearby islands, where they were hunted nearly to the point of extinction in the 19th century. More common California sea lions, or lobos marinas, live on and around several islands in the Sea of Cortez, including Isla Ángel de la Guarda near Bahía de los Angeles  and Isla Espíritu Santo near La Paz .
Marine biologists have labeled the Sea of Cortez the richest body of water in the world. Diverse marine environments along both sides of the Baja Peninsula support thousands of species of fish. There are sailfish and marlin (collectively called billfish); corvinas and croaker, including the protected totuava; yellowtail, amberjack, pompanos, and roosterfish; dorado (mahimahi), wahoo, and bluefin, albacore, and yellowfin tuna, which can grow to sizes exceeding 180 kilograms (400 lbs.); various types of sea bass, including garropa (grouper) and cabrilla; flounder and halibut; snappers (pargo, including the red snapper, which is called huachinango in Spanish). More than 60 types of sharks live here, among them the hammerhead, thresher, bonito (mako), bull, whitetip, sand, blue, blacktip, and whale shark—the world’s largest fish at 18 meters (59 ft.) and 3,600 kilograms (almost four tons).
Eagle rays, guitarfish, stingrays, and other rays often rest on the sandy bottom of the sea, offshore from the southern part of the peninsula. Divers and snorkelers are sometimes lucky enough to see the Pacific manta ray glide by. With a wingspan of up to seven meters (23 ft.), it can weigh nearly two tons.
The Humboldt squid is another unusual deepwater creature. It grows to 4.5 meters (15 ft.) long and weigh up to 150 kilograms (330 lbs.).
Barracuda are found in both the Pacific and the Sea of Cortez. And in Southern Baja, the flying fish puts on a good show as it leaps out of the water offshore.
Abundant shellfish, including clams, oysters, mussels, scallops, and shrimp, and spiny lobster, are found all along the coast.
With this great variety of plant and fish life comes an equally fantastic bird population. Ornithologists have identified at least 300 species, but unfortunately no one has published a Baja-specific field guide to date, though several Mexican bird guides include the species found on the peninsula and its islands.
Baja California Sur Birds (BCS Birds, www.bcsbirds.com ) is dedicated to raising awareness of the area’s potential as a world-class bird-watching destination. The BCS Birds website is designed as a reference for naturalists and birders who wish to identify what they have seen here and who wish to learn what species are regularly observed in Baja California Sur.
The Midriff Islands in particular provide habitat for many rare and endangered species, and the Mexican government protects 49 of these islands as wildlife preserves. Well known among birders, Isla San Pedro Mártir has the blue-footed booby as well as the brown booby and masked booby. Tiny Isla de Raza is another popular birding destination.
Brown pelicans are common in Baja but gone from the coastal islands of California and the U.S. shores of the Gulf of Mexico. Other noteworthy birds include the frigate, fisher eagle, cormorant, egret, gull, heron, loon, osprey, plover, sandpiper, and tern.
Boaters sometimes see pelagic birds such as the albatross, black-legged kittiwake, red phalarope, shearwater, surf scoter, south polar skua, storm petrel, black tern, and red-billed tropic bird.
The inland ponds, springs, lakes, streams, and marshes of Baja support two species of bittern, the American coot, two species of duck, the snow goose, the northern harrier, six species of heron, the white-faced ibis, the common moorhen, two species of rail, five species of sandpiper, the lesser scaup, the shoveler, the common snipe, the sora, the roseate spoonbill, the wood stork, three species of teal, the northern waterthrush, and the American wigeon.
The golden eagle, western flycatcher, lesser goldfinch, black-headed grosbeak, red-tailed hawk, pheasant, yellow-eyed junco, white-breasted nuthatch, mountain plover, acorn woodpecker, and canyon wren live in the peaks and valleys of the sierras, along with two species of hummingbird, four species of vireo, and eight species of warbler.
Falcons, flycatchers, hawks, hummingbirds, owls, sparrows, and thrashers live in the hot, dry desert environment, along with the American kestrel, merlin, greater roadrunner, vernon, turkey vulture, ladder-backed woodpecker, and cactus wren.
The largest bird in North America is the endangered California condor (Gymnogyps californianus), which weighs up to 11 kilograms (24 lbs.), with a wingspan of nearly 3.6 meters (12 ft.). A group of U.S. and Mexican scientists plans to release captive-bred condors in Baja’s Sierra de San Pedro Mártir in hopes that the more limited human presence will permit the bird to survive in the wild.
Thirty types of lizards live on the Baja Peninsula, including the large chuckwalla, which inhabits several islands in the Sea of Cortez and can grow to one meter (3 ft.) long. The desert iguana and the endemic coast-horned lizard are also noteworthy species. With lots of color photos, Amphibians and Reptiles of Baja California, by Ron McPeak can help you identify the many frogs, toads, salamanders, snakes, and lizards of the peninsula.
Five sea turtles live in Baja waters: the leatherback, green, hawksbill, western ridley, and loggerhead, which swims 10,460 kilometers (6,500 mi) between the island of Kyushu in Japan and the Sea of Cortez. All these turtles are endangered, and it’s illegal to hunt any of them or collect their eggs, but enforcing the law has been a challenge.
Many organizations are involved in turtle conservation efforts in Baja. One of the largest is Grupo Tortuguero (www.grupoturtuguero.org ), which holds its annual meeting in late January–early February in Loreto. A who’s who of Baja influencers usually attends.
There are 35 species of snakes (serpientes) in Baja, about half of which are poisonous, although they rarely come into contact with people.
Nonvenomous kinds (culebra) include the western blind snake, rosy boa, Baja California rat snake, spotted leaf-nosed snake, western patch-nosed snake, bull snake, coachwhip, king snake, Baja sand snake, and California lyre snake.
Among the poisonous types (víbora) are the yellow-bellied sea snake, which resembles a floating stick in the water, and 18 species of rattlesnake (serpiente de cascabel or cascabel), including the common Baja California rattler, red diamondback, and western diamondback, which is the largest and most dangerous of Baja’s snakes and lives in the canyons of the northern sierras.
The only rattler that’s endemic to Baja California is the rattleless rattlesnake (Crotalus catalinensis), which lives only on Isla Santa Catalina in the Sea of Cortez.