California, located in the western United States, is the most populous state in the country. Many of the state’s territories were transformed into residential areas, destroying the natural habitats of numerous animal and plant species. This article discusses several endangered animals living in California, along with their status and current threats to their numbers.
California is, in fact, abundant in unique flora and fauna; it hosts some of the largest and tallest trees in the world, for instance, and many unique animal species that do not inhabit any other area in the world.
Unfortunately, many of them are on the brink of extinction, primarily due to habitat loss caused by urban and agricultural development. We’ve selected some species found in California that are either Endangered or Critically Endangered on the IUCN Red List, and we were surprised to learn that most of them are endemic to California. Keep reading to find out more about these animals!
1. Salt-Marsh Harvest Mouse
The salt-marsh harvest mouse is also called the red-bellied harvest mouse. It has dark brown fur on its upper parts and tawny undersides. However, the coloration in northern mice is slightly different, as they’re brown or reddish brown dorsally, while the underparts are white or cream with shades of red. Additionally, it has a bicolored tail. Most adult mice are 2 – 3 inches long and have a 2 – 4-inch-long tail.
These mice live only in California, in the salt marshes bordering San Francisco Bay. The species was assessed as Endangered in 2017, although it was first listed as Endangered in 1982.
The salt-marsh harvest mouse population is steadily declining. It is severely fragmented, primarily because of habitat destruction. Urban development, the intrusion of freshwater into salt marshes, and residential encroachment has destroyed around 84% of the original San Francisco Bay tidal marshes. Predators have also played a role in the decrease of salt-marsh harvest mouse individuals.
2. Perrin’s Beaked Whale
The Perrin’s beaked whale is scientifically called Mesoplodon perrini and is part of the Ziphiidae family. This whale has a relatively small head, a deep peduncle, a long abdomen and thorax, and a short tail. Females usually grow up to 14.5 feet, while males are slightly smaller, measuring around 13 feet.
These whales live in the warm-temperate waters of the eastern North Pacific Ocean, meaning they only inhabit California and possibly Mexico. Their population is constantly declining, and only 500 to 1,164 mature individuals remain.
Drift gillnets and longlines, which are abundant in the ocean, primarily affect these whales. Moreover, scientists believe loud underwater sounds, primarily those from military vessels, may adversely affect Perrin’s beaked whales. In fact, these sounds may cause chronic and acute tissue damage. Besides this, numerous plastic elements in the water pose a major threat, as whales often ingest them, and the plastic eventually blocks their digestive tract.
3. Southern Mountain Yellow-Legged Frog
The southern mountain yellow-legged frog is a multi-colored amphibian, having a yellowish, olive, or brownish body with distinctive brown or black markings. The hind legs have various yellow shades, while the throat is white, cream, or yellow. Moreover, the yellow-legged frog has a dorsal pattern with distinctively shaped dark spots.
This frog is endemic to California but has disappeared from much of its historical range. It now inhabits only the Sierra Nevada and parts of southern California, where it occurs in isolated subpopulations. Only 500 – 2,499 mature individuals remain, and their population has declined since the late 1960s.
Biologists believe that, back in the 1960s, the introduction of non-native fish and diseases threatened these frogs. However, researchers haven’t confirmed these causes.
Other threats might have included wildfires, human recreational activities, and other stressors. Some scientists found evidence that airborne agrochemicals, UV-B radiation, and acid precipitation played a major role in the population decline.
4. Nelson’s Antelope Squirrel
Nelson’s antelope squirrel is also called the San Joaquin antelope squirrel. It’s a small species, with males measuring 9.8 inches and females 9.4 inches. They have pale yellowish-brown coats on the upper parts, becoming white on the underside. The underside of the tail is white and features black edges.
Like other species on our list, this squirrel is endemic to California, living in the western part of the San Joaquin Valley. Researchers do not know the size of the population. However, it is severally fragmented.
Habitat loss highly threatens the species. Urban and agricultural development, petroleum extraction, solar energy, and rodenticides are to blame for this loss.
5. Coachella Valley Fringe-Toed Lizard
The Coachella Valley fringe-toed lizard is a distinctive reptile with elongated scales covering its ears, a wedge-shaped nose, and distinctive nostrils specialized in breathing below the sand. This lizard lives only in California, the Coachella Valley, and Riverside County.
Although researchers do not know the population size, it’s constantly decreasing, primarily because of urban and agricultural development. Around 80 – 90% of the historical natural habitat of this species has been destroyed, and roads severely fragment the remaining territory. Moreover, another cause for the population drop may be sand migration through the winds, which affects the lizards.
6. Santa Cruz Black Salamander
Just as its name implies, the Santa Cruz black salamander is completely black, although juveniles have some tiny white spots. These salamanders live only in four to five locations in California. Their population started declining a few decades ago and continues to do so due to habitat degradation.
The seeps and creeks these salamanders inhabit are often converted into agricultural sites or rural housing. Besides this, a disease called the salamander chytrid fungus affects these critters. Climate change also played a role in the population drop, as the area these salamanders live in is generally drier and hotter than it was years ago.
7. Arroyo Toad
Arroyo toads are a small species, measuring around 2 – 3 inches long. They have greenish, grayish, or pinkish bodies and a light stripe across the head and eyelids. These toads inhabit Baja California and California, in coastal drainages. Their population is believed to have registered a reduction of around 65% since 1990, and no evidence indicates that any subpopulation is increasing.
A major threat to the arroyo toad population is urban development, which causes habitat degradation, fragmentation, and loss. Agricultural activities affect arroyo toads, too, primarily through groundwater pumping, contaminated runoff, and water diversions. Moreover, introduced non-native fish and frog species became predators of arroyo toads, thus contributing to the decrease in mature individuals.
8. San Francisco Forktail
As the name suggests, the San Francisco forktail inhabits only the San Francisco Bay Area of California. This is a damselfly, measuring around 0.98 inches long. These insects have distinctive bodies with beautiful coloration. Males are usually black on top and blue on the sides, while females are typically dull green on the sides of the thorax.
Although the current population size is unknown, the San Francisco forktail may have disappeared from some historically inhabited localities. This is primarily caused by habitat destruction and degradation due to urbanization. On the other hand, these insects are somewhat resistant to pollution, meaning there’s still a chance they could survive and avoid complete extirpation.
9. Sunflower Sea Star
The ninth animal on our list is a sea star! Scientifically called Pycnopodia helianthoides, the sunflower sea star is part of the Asteriidae family. It has an arm span of up to 3.3 feet, making it the world’s second-biggest sea star! Unfortunately, the species is on the brink of extinction since conservationists assessed it as Critically Endangered in 2020 after a global outbreak of sea star wasting disease. Their population reduced by 90.6%, and the disease killed more than 5 billion sea stars!
However, the disease isn’t the only threat to the sunflower sea star population. Climate change is important, too, as warmer temperatures speed the progression of sea star wasting disease, thus killing many more individuals.
The photo featured at the top of this post is © George Lamson/Shutterstock.com
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