California’s delicate ecosystems face a growing threat from unwelcome reptilian visitors. These non-native species compete with local wildlife for food and habitat, often with devastating consequences.
From suburban backyards to protected wilderness areas, invasive reptiles are changing California’s natural balance in ways that concern scientists and nature lovers alike.
1. Red-Eared Slider Turtles
Once popular pets released into the wild, red-eared sliders now dominate California’s ponds and lakes. Their aggressive nature allows them to outcompete native western pond turtles for basking spots and food resources.
These hardy turtles can live up to 30 years in the wild, creating long-term ecological problems. Their omnivorous diet includes aquatic plants, small fish, and invertebrates that native species depend on.
2. African Clawed Frogs
Originally imported for pregnancy testing in the 1940s, African clawed frogs established thriving populations in Southern California waterways. Their voracious appetite makes them formidable predators of native amphibians and fish.
Remarkably adaptable, these frogs can survive in nearly any freshwater habitat and even travel short distances over land. They carry the chytrid fungus that’s devastating amphibian populations worldwide without succumbing to it themselves.
3. Brown Anole Lizards
Brown anoles arrived in California through the nursery trade, hiding in potted plants. Now established in several counties, these agile lizards from Cuba and the Bahamas push out native lizard species through direct competition.
Small but mighty, brown anoles reproduce rapidly, with females laying one egg every week during breeding season. They feast on the same insects that native lizards rely on, creating a food shortage for indigenous species.
4. Burmese Pythons
While not yet widespread in California, occasional Burmese python sightings cause alarm among wildlife officials. Released pets grow enormous, with some reaching over 15 feet long, capable of consuming deer and even alligators.
The climate in southern California could potentially support these massive constrictors year-round. Florida’s Everglades provide a cautionary tale, where pythons have decimated mammal populations by up to 99% in some areas.
5. Mediterranean House Geckos
Stealthy Mediterranean house geckos have established colonies in urban and suburban areas across California. These pale, translucent lizards with bulging eyes are often spotted on walls near porch lights, hunting insects at night.
Highly adaptable to human environments, they thrive where native species cannot. Though their ecological impact seems limited to urban areas, they represent how easily non-native species can establish themselves when introduced through global trade.
6. Green Iguanas
Former pet green iguanas now roam free in parts of Southern California, particularly in urban parks and canal systems. Growing up to six feet long, these herbivores strip vegetation and damage native plant communities essential to local wildlife.
Female iguanas dig extensive burrows for nesting, causing erosion along waterways and undermining infrastructure. Their population boom demonstrates how quickly released pets can establish breeding populations in California’s hospitable climate.
7. Jackson’s Chameleons
With their three horns and swiveling eyes, Jackson’s chameleons might look fascinating, but their presence in California spells trouble. Released or escaped pets have established breeding populations in coastal areas, particularly in San Diego County.
Native to East Africa, these colorful reptiles prey on native insects and small invertebrates. Their specialized hunting techniques and excellent camouflage make them efficient competitors against California’s native insectivores, disrupting local food webs.
8. Common Wall Lizards
European wall lizards have quietly invaded several California communities, especially in the Bay Area. Their mottled brown appearance helps them blend into urban environments, where they scurry along walls and fences hunting insects.
Extremely adaptable, these lizards tolerate colder temperatures than many native species. Research suggests they’re expanding their range and competing directly with native western fence lizards for territory and food resources in increasingly urbanized landscapes.
9. Argentine Black And White Tegus
Among the newest reptilian invaders, Argentine tegus have been spotted in multiple California locations. These large, intelligent lizards grow up to four feet long and have an omnivorous appetite that includes eggs, fruits, vegetables, and small animals.
Ground-nesting birds and turtles face serious threats from tegus, which raid nests and consume eggs. Their intelligence makes them difficult to trap, while their varied diet and cold tolerance allow them to thrive in diverse California habitats.
10. Mediterranean Geckos
Different from their house gecko cousins, Mediterranean geckos have established themselves primarily in Southern California’s urban environments. These vocal reptiles make distinctive clicking sounds during mating season, often heard around homes and businesses at night.
Excellent climbers, they scale buildings to hunt insects attracted to lights. While their impact on native ecosystems appears limited to urban areas, they represent the ongoing introduction of non-native species through global shipping and the pet trade.
11. African Spurred Tortoises
Abandoned pet African spurred tortoises now roam wild in parts of California’s desert regions. As the third-largest tortoise species worldwide, these giants can weigh over 100 pounds and create extensive burrow systems that alter desert landscapes.
Their powerful legs and shells damage native vegetation through trampling. Though currently limited in distribution, wildlife officials worry about their potential impact on the endangered desert tortoise through competition for scarce resources and habitat modification.
12. Italian Wall Lizards
Italian wall lizards bring vivid green coloration to California landscapes where they’ve established colonies. Believed to have escaped from a private collection in Los Angeles County, these European natives now compete with local species.
Fast and agile, they’re excellent climbers that hunt insects native lizards depend on. Scientists monitor their spread with concern, as studies from other invaded regions show they can displace native lizards through aggressive behavior and more efficient foraging techniques.
13. Brahminy Blind Snakes
Tiny but troublesome, Brahminy blind snakes arrived in California soil with imported plants. Often mistaken for earthworms due to their small size and pinkish-brown color, these parthenogenetic females reproduce without males, allowing rapid population growth.
Living underground, they feed on ant and termite eggs and larvae, potentially disrupting soil ecosystems. Their presence often goes undetected until populations are well-established, making control efforts challenging and highlighting the invisible nature of many biological invasions.