Species Spotlight: Coast Horned Lizard
Our Spiny Little Friends
From the sand in the deserts to the drought-resistant foliage of our coastal sage scrub habitats, there are many fun surprises to be found in the vastness of the outdoors. The most well-known critters found in these environments include snakes, rodents, and even large mammals like coyotes, but there are many underappreciated species to be found hiding right under our noses! One of these species is the Coast Horned Lizard (Phrynosoma blainvillii): a rare lizard species found in Southern California known for their unique appearance, including horns with fascinating characteristics. While you may not have heard of them before, these small creatures definitely have the looks and personality to be brought into the limelight, so let’s jump into what makes these lizards so fascinating and learn more about them and their environment!
What is the Coast Horned Lizard?
The Coast Horned Lizard (Phrynosoma blainvillii), is one of only four horned lizard species found in California.They are typically a tan or yellowish-brown color, but they can also be found in a gray or even reddish color based on the environment around them; this is a type of camouflage they use to blend into the substrate of their habitat. They are typically around 6-8 inches long, but don’t let their small size fool you; what they lack in size is made up for by their other more outlandish features. In fact, the Coast Horned Lizard is also known as the “horned toad” because of their round, flat body shape and horns that surround their head and run down the length of their body. Despite this nickname, it’s important to note that the Coast Horned Lizard is not a true toad: while they have a similar warty appearance, true toads are also toothless and belong to the bufonidae family. Additionally, they have two prominent horns on the top of their head that creates a threatening image for these small but mighty creatures.
Coast Horned Lizard with its signature spikes. PC: USFW
Coast Horned Lizards are insectivores, meaning they primarily eat insects. In fact, 90% of their diet consists of ants, particularly native harvester ants, but they also eat a variety of arthropods such as beetles, spiders, and grasshoppers. Because of this, they can typically be found near anthills or near small plants and shrubs where insects spend a lot of time. Because they are foragers and must hunt out in the open for their food, they are at risk themselves of being attacked by a predator when looking for food of their own.
The Coast Horned Lizard is preyed upon by a variety of species, such as snakes, hawks, coyotes, and more! To avoid becoming prey, they must employ a variety of techniques to protect themselves. One primary defense is their natural coloration, which helps them use a type of camouflage - called cryptic camouflage - to blend into their surroundings and hide from predators. Additionally, they can swallow large amounts of air and actually inflate themselves to 2 times their original size (like a giant, spiny balloon!) to make themselves look bigger and more threatening to potential predators. The most unique and unusual defense is something you would see right out of a horror film: they are able to shoot a stream of blood out of the corners of their eyes! They do this by limiting blood flow to their head, which builds up pressure in blood vessels in their face, and eventually the pressure builds so high in their eyes that the blood vessels burst and shoot out a stream of blood (Watch a cool video from Nat Geo Animals here). This can distract or even blind their predators, allowing the Coast Horned Lizard time to flee. However, this mechanism is very taxing and is therefore only used as a last resort.
The Coast Horned Lizard uses cryptic coloration to blend into its surroundings. PC: Dan Sandri, Mount Diablo Interpretive Association, California State Parks.
Habitat:
Historically, the Coast Horned Lizard can be found throughout southern California, from Baja California all the way into the central valley, the Sierra Nevada mountains, and even the Mojave desert.
Range and distribution of the Coast Horned Lizard Throughout California. PC: CDFW
Similar to other lizards, the Coast Horned Lizard is ectothermic, or cold-blooded, meaning they cannot regulate their own body temperature and must rely on the temperature of the environment to stay warm. Because of this, they prefer to live in hot desert or dry arid climates. These warmer regions give them plenty of access to the sun and allow them to bask in the open to raise their body temperatures. They can be susceptible to overheating, however, so they also can be found in shady areas or getting cozy in burrows to stay cool when it gets too hot outside.
In these regions, the Coast Horned Lizard can be found in a variety of habitats including, but not limited to: coastal sage scrub, dunes, and chaparral. Within these habitats, they have a much stronger preference for microhabitats, or small areas with more specific conditions that differ from the surrounding habitat. These species prefer areas with fine, loose soils for burrowing, open areas for thermoregulation (the ability for an animal to control and maintain their body’s temperature), and occasional shrub coverage for defense.
Threats to the Coast Horned Lizard:
While the Coast Horned Lizard is not federally listed as an endangered species, they are listed as a California species of special concern due to significant population declines. Their dwindling population numbers are primarily due to loss of their natural habitat through wildfires and urban and agricultural expansion. Wildfires increase the mortality rate of many species, and often cause them to be displaced or even destroy the special habitats they need to survive. Human interference and expansion also increases mortality rates and causes them to be displaced, further disrupting the ecosystem.
Additionally, the introduction of the non-native Argentine ants (Linepithema humile) into California has caused the displacement of many native ant prey species, which is dangerous because Coast Horned Lizards will not eat Argentine ants. Previous studies have shown that the Coast Horned Lizard’s prey selection is based on ant body size and foraging behavior, which means the much smaller Argentine ants are not a suitable replacement food source for the native ant species that are being displaced (Suarez et al., 2000). As the number of native species is overtaken by the Argentine ants, the availability of their food source decreases, which is causing their population numbers to drop.
How to Help:
With such a unique species, you may want to get involved and spread awareness about our spiky little friends. Here are a few things you can do to get involved in conservation efforts:
Keep Learning: The first step in conservation is learning more about a species and the challenges it faces. If you’re interested, the EcoVivarium Reptile Sanctuary and Museum has live animals you can visit, and the San Diego Natural History Museum has extensive resources where you can learn more about the Coast Horned Lizard!
Support organizations in their ongoing conservation projects: Groups such as the San Diego Multi Species Conservation Plan and The Nature Reserve at Rancho Mission Viejo are working to combat the effects of urban expansion and habitat loss. You can help these efforts by donating your time or money to support these important causes!
Spread awareness: By using your new-found knowledge and sharing it with others in the community, you can help raise awareness to these issues and the importance of conservation efforts.
Support OC Habitats’ efforts: We here at OC Habitats love to give back to our local ecosystems through educational events and restoration projects. Although we do not work with this species directly, the conservation work we do here has a ripple effect that helps protect this species and many others, and we would not be able to do it without the support of amazing people in the community like you!
The Coast Horned Lizard is a unique species and is important to the general ecosystem. By learning more about them and what we can do to protect them, you can give back the environment and play an important role in protecting the amazing life we see in the natural world!
Sources:
"Blood Shooting Eyes | World's Weirdest" YouTube, uploaded by Nat Geo Animals, January 3rd 2014, https://youtu.be/xodVcgJ8bc0?si=TJ8Pi1SFF7vnLyuu&t=102
Suarez, A. V., Richmond, J. Q., & Case, T. J. (2000). Prey selection in horned lizards following the invasion of Argentine ants in southern California. Ecological Applications, 10(3), 711-725.
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