Invasive Frog Species

Frogs are amazing creatures that contribute in incredibly positive ways to their natural ecosystems.

But certain frog species can be found in places they should not be located, and are causing havoc within their new environments.

These are invasive frog species, and they pose a serious threat to native wildlife.

Some invasive frog species include the American Bullfrog in Western USA and Canada, Cane Toads in Florida, the Caribbean and Pacific islands, Cuban Tree Frogs in Hawaii, and African Clawed Frogs in California.

Invasive frog species consist of Anuran species that were displaced from one location and introduced to a new environment.

They may have been moved there for economic, ecological, or environmental reasons which commonly backfire leading to ecological and economic issues.

Here is a quick overview of some frog species and where they are invasive:

Invasive species generally cause ecological harm in a new environment where they are non native, notably by feeding on native wildlife. Whereas native species are indigenous to their location or ecosystem and often suffer due to other invasive animals and plants.

“Invasive species have become one of the greatest environmental challenges of the twenty-first century in economic, environmental, and human health costs.”

Fort Collins Science Center

The reason frogs are taken from their natural habitat and placed in new environments is due to human activity, from agriculture, to farming, accidental transportation on vessels, and the pet trade.

Let’s have a closer look at why these frogs became invasive and the impact their presence has on the locations where they now live.

American Bullfrogs

American Bullfrogs are an invasive species in the Western United States and Canada, and are the largest frog species in North America.

Being the largest species in North America provides Bullfrogs an advantage over other frog species since they can consume large prey, from rodents to birds, bats, lizards, and snakes.

Although American Bullfrogs are native to Eastern North America, they were imported to the Western United States, and British Columbia, Canada for farming purposes.

Because of their large size, American Bullfrog legs are considered a delicacy in parts of North America as well as in many Asian countries.

However, some of the frogs were either released or escaped their farming grounds and have proliferated due to the large amount of eggs they lay per reproductive cycle (up to 20,000 eggs per year), as well as their sheer size, ability to migrate over large expanses of land, feed on a wide range of small and large native prey, thrive in human habitats, as humans catching and releasing them into new areas. 

Cane Toads

Cane Toads are native to South America and were introduced into many new regions in the 1930’s to lower the population of destructive agricultural beetles. The introduction aimed to aid the growth of cane crops, but the species soon overpopulated areas, posing risks for surrounding wildlife.

The plan to use Cane Toads as a natural way to eradicate beetles completely backfired. Toads cannot jump very high or climb, and the beetles were located high in the cane. Therefore, the toads just went on to feed on other native wildlife.

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Not only did introducing Cane Toads not solve the pest issue, some regions experienced massive levels of destruction to native wildlife due to this species. Cane Toads are highly adaptable, large, and toxic, making it challenging for neighboring species to thrive and reproduce. 

Cane Toads lay up to 30,000 eggs twice per year, their tadpoles are also toxic and mature much faster than most amphibian species. Their presence has overwhelmed some areas and threatened the continuation of many iconic species. 

Cane Toads have given many other toad species a bad reputation, whereas toads are very important to their native location and also fall prey to larger Cane Toad populations. Therefore, it is key to ensure you are not killing native toads when dealing with Cane Toads.

Read more about invasive Cane Toads on our blog

Cuban Tree Frogs

Cuban Tree Frogs are fairly large tree frogs that are native to Cuba and the surrounding islands. Cuban Tree Frogs were introduced to Florida, Hawaii and the Caribbean islands in the 1950’s due to their being accidentally located and transported on cargo containers and ships.

Due to their size, wide diet, and ability to climb, Cuban Tree Frogs pose an economic and ecological threat to the locations where they were introduced. They feed on smaller, native frog species. One study found that invasive frog species are 40% more likely to eat other frogs (Measey et al, 2015).

Their tadpoles also compete with and eat native frog tadpoles due to their larger size and faster growth rates.

Cuban Tree Frogs have a tendency to cause blackouts and damage electrical equipment by creating short-circuits since they climb up telephone and electric poles. This is a privileged location for them to perch and gain easy access to bugs that fly around street lights at night.

Blackouts and other electrical issues are caused when the frogs come into contact with surfaces that carry an electrical charge. Power outages have caused hundreds of thousands of dollars of damages and repairs in their introduced locations since the 1990’s (CTNF).

Cuban Tree Frogs can often also be found and around people’s homes since they thrive in urban areas. The frogs are attracted to lights (which attract bugs), pipes, skins, and toilets which contain a key element for their survival: water. The frogs often clog drains and cause plumbing issues in older homes.

Find out how to keep frogs out of your home on our blog

African Clawed Frogs

African Clawed Frogs are fully aquatic frogs that are popular pets and species used for biological study in laboratories.

However, due to being released in the wild by their caretakers, these frogs have become invasive in California, and have also been found in waterways in Arizona, Colorado, Florida, Massachusetts, North Carolina, Virginia, and Wisconsin.

These frogs are still being introduced into the wild in the USA due to escaping, or being released by pet owners, research facilities, and laboratories throughout the country. They are of particular problem in California where it is illegal to possess an African Clawed frog, or to import or transport one without a permit.

These frogs are extremely adaptable, can estivate during dry seasons, and can migrate long distances. African Clawed frogs are a good example of why you should never release your pets into the wild.

Common Coquí

Common Coquí frogs are native to Puerto Rico and were accidentally brought to Colombia, Hawaii, and the Virgin Islands in the 1980’s due to their presence on cargo ships. 

The frogs quickly established themselves on the islands where they were introduced and their density of population is so high in some areas that there are more than 51,000 Coquí per hectare. When populations reach such densities, the frogs can consume over 300,000 invertebrates per night. 

Common Coquí have a devastating economic and ecological impact on the locations where they were introduced, reaching nearly $3,000,000 USD per year. They feed on native wildlife, and have also reduced the costs of real estate in certain locations due to their very loud calls at night.  

Common Coquí are on the top 100 list of the world’s most invasive species.

Keep in mind, however, that not all of these species are invasive in the locations where they can be found. American Bullfrogs, Cane Toads, and other invasive species on this list are often not considered invasive in their native habitats. For example, American Bullfrogs are common and non-problematic in the Eastern United States and in Canada where they originate from.

What to Do About Invasive Frog Species

Each and every jurisdiction has a specific way of dealing with invasive species. 

For example, in The British Columba government recommends that locals “trap [American Bullfrogs] if possible, and have [them] exterminated once clear identification is made by a professional.”

Whereas in California, the government recommends reporting  sightings of African Clawed Frogs to the CDFW Invasive Species Program, by email to [email protected], or by calling (866) 440-9530 (CTNF).

This information may change over time, therefore, we cannot provide location specific recommendations on dealing with native species of frogs.

However, we linked to an article below that includes location-specific Wildlife Department phone numbers to call for location-specific recommendations on dealing with invasive frogs.

See how to deal with invasive frog species on our blog

Keep in mind that the reason there are invasive frogs in your location is human activity. Therefore, it is our own fault these invasive frogs are where they are today. Always consider humane ways to deal with invasive animals and be kind when handling them.

Sources

National Invasive Species Information Center, Invasive Species

California Department of Fish and Wildlife, Invasive Species

BC Government, Invasive Species

University of Florida News, Invasive Cuban Tree Frogs threaten native wildlife, damage utilities, says UF expert.

Alaska Government, Non Native and Invasive Species

Fort Collins Science Center, Biological Threats and Invasive Species

Karen H. Beard, Robert Al-Chokhachy, Nathania C. Tuttle, Eric M. O’neill. Population Density Estimates and Growth Rates of Eleutherodactylus coqui in Hawaii. Journal of Herpetology, Vol. 42, No. 4, pp. 626–636, Society for the Study of Amphibians and Reptiles, 2008.

Measey GJ, Vimercati G, de Villiers FA, Mokhatla MM, Davies SJ, Edwards S, Altwegg R. 2015. Frog eat frog: exploring variables influencing anurophagy. PeerJ3:e1204 https://doi.org/10.7717/peerj.1204