Invasive Species

Florida is home to thousands of non-native species of plants and animals. When these introduced species reproduce in the wild and cause either economic, social or ecological disturbance they reach “invasive” status.

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What we do

The Conservancy has responded to the emerging threat of invasive species by focusing research and removal efforts on critical invasive species for the bio-region.

Conservancy wildlife biologists and research partners are working to better understand the behavior and ecological impact of these species, such as the Burmese python (Python bivittatus) and the cane toad (Rhinella marina).

The Conservancy’s goal is to contribute science-based solutions to control the spread of invasive species in an effective and humane manner.

Our Invasive Species Work

“If we can continue to target breeding female pythons for removal the results are two-fold. We are keeping the invasive snakes from multiplying and reducing the overall impact on our native wildlife populations.”

- Conservancy President & CEO Rob Moher

As of April 2021, Conservancy biologists and project volunteers have removed over 20,000 pounds of python (9,072 kg) from approximately 100 square mile area (259 km2) in southwestern Florida.

Background

The Burmese python (Python bivittatus) is one of the largest species of snake in the world, known to grow almost 19 feet (5.8 m) in length. They are a generalist predator, using their large size and powerful coils to subdue and suffocate prey. Native to Southeast Asia, hundreds of thousands of pythons were brought to Florida through the pet trade starting in the 1970s. First observed in Everglades National Park in 1979, they have now become an established apex predator across the Greater Everglades ecosystem. Burmese pythons are thought to be responsible for a 90% decline in native mammal populations across their established range.

Burmese Python Radio-Telemetry Study

Since 2013, the Conservancy and research partners have been conducting radio-telemetry fieldwork to document python biology and behavior in Collier County. To date, 86 adult Burmese pythons have been radio-tagged and tracked across Southwest Florida.

A primary objective is to create a database of behavior and habitat use to better understand python activity in the bio-region. Our research is used to inform decision makers and land managers to develop a control strategy for this invasive species.

Tracking

Adult pythons are captured, surgically implanted with a radio-transmitter, and released back at the capture site. These individuals are referred to as “scout snakes” for their ability to lead researchers to other pythons during the breeding season.

Removal

The Conservancy’s snake team uses a combination of active searching and telemetry to remove invasive pythons from Southwest Florida. Closely monitoring scout snakes during the breeding season allows the team to locate and remove animals that otherwise wouldn’t be detected, effectively utilizing their behavior against them.

“By utilizing the scout snake technique we can target undetected breeding female pythons and effectively remove them from the ecosystem before they have a chance to lay eggs” - Ian Bartoszek, Conservancy Research Manager

Necropsy

Captured pythons are humanely euthanized and necropsied at the Conservancy’s invasive species lab. Data is recorded on animal size, condition, and breeding potential. Tissue, gut content, and other samples are collected for future analysis. Collaborative researchers have used samples and specimens from the Conservancy effort to identify prey items, examine mercury content, test hormone levels, and more.

General Information

COMMON NAMES:  CANE TOAD, BUFO TOAD, MARINE TOAD, OR GIANT TOAD.

Cane toads are one of the largest species of toad in the world. Native to South America, the species was originally introduced to Florida in the 1930s and 40s in an attempt to control agricultural pests in sugar cane fields, and the pet trade contributed with releases and escapees during the 1950s and 60s.

Cane toads are not aggressive, but they have enlarged parotoid glands on their neck and shoulder region that produce a bufotoxin that, when ingested, is highly toxic. This toxin is capable of causing severe illness or death to potential predators. The toads also have a big appetite and are capable of eating just about anything they can fit into their mouths. These traits are posing a threat to our native wildlife, and to any pets that attempt to attack them.

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IDENTIFICATION

It is important to know that there are other toad species native to Southwest Florida. The native southern toad (Anaxyrus terrestris) is the species most likely to be misidentified as the cane toad. Both species occupy the same habitats and therefore can be found together.

The large size is often the first noticeable feature of cane toads. Cane toads can reach 6-9 inches in length as adults, while southern toads have been known to reach a maximum length of 4 inches. However, cane toads are not always bigger than southern toads, so it is important to be familiar with features that help distinguish the species when they are both a similar size.

The best feature to look for are the southern toad head crests! When southern toads are around an inch and a half in length they start to display small ridges or crests on their heads, between the eyes, while the area between cane toad’s eyes will always remain flat. It is almost impossible to distinguish the two species when they are at any other life stage (eggs, tadpoles) or smaller toad in size.

Please watch the video below for helpful information on how to properly identify a cane toad:

Cane Toads - How to Identify This Invasive Pest

southern toad vs cane toad

Toad Comparison Graphic

HUMANE EUTHANASIA OF CANE TOADS

Cane toads can be removed, and humanely euthanized, by property owners or hired wildlife trappers. It is best to avoid any chance of accidently removing native southern toads by only removing those toads that exceed the inch and a half length, at which time the species can be distinguished from one another (see identification section above). The link below gives recommendations regarding the humane euthanasia of cane toads. Euthanasia is sometimes necessary for the safety of pets and the good of local wildlife. The methods discussed on this video are supported by the best available science to date and is the most appropriate way of killing these animals to ensure they do not feel pain. Do not relocate captured cane toads to another location.

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Prevention is key

Prevention is the best way to avoid an unfortunate and possibly fatal interaction involving your pet. Always keep your dog on a leash when walking outside, especially on warm evenings and after rain, and make your yard less toad-friendly by removing any attractants such as pet food, or debris piles where toads can hide. Also, keep the number of your local emergency veterinarian handy. In the event of poisoning, you must act quickly!

Please watch the video below to learn more about tips for prevention of toad-pet interactions, properly identifying the symptoms of cane toad poisoning, and knowing what to do in the event of a poisoning:

The Cane Toad - An Invasive Impact on Florida Pets

Conservancy cane toad research

In 2019, through philanthropic funding, the Conservancy of Southwest Florida began a research collaboration with the University of Florida and the Florida Fish and Wildlife Conservation Commission to study cane toads within southwest Florida. Biologists are studying cane toads using three distinct methods: radio-telemetry tracking, trap/lure design testing, and diet analysis. The broad scope of the research focuses on answering life history questions regarding the movement, behaviors, and habitat preferences of cane toads in urban landscapes. Understanding interactions with native species and identifying ‘at risk’ areas will contribute to the creation of management plans, which could help prevent the spread of cane toads into natural areas.

The current cane toad range in Florida is shown on the map below which was created by UF, IFAS Extension. The isolated population in the southwest Florida region is the focus of our research.

While it appears that currently the toads have a preference for urban locations within the invaded areas, it may only be a matter of time before they disperse into neighboring natural areas. Cane toads have potential to cause a lot of damage directly (eating and poisoning native wildlife) and indirectly (competing for resources and creating negative public backlash towards native toads) to the natural environment.

Cane toad range map

Radio-telemetry tracking

Adult toads are fitted with a radio-transmitter attached to a belt, which sends a radio signal that can be heard using a receiver. This enables researchers to locate the toads again after they have been released back to their original location. Care is taken to ensure that the external attachments will not interfere with any of the toad’s natural movements or behaviors. These animals are located twice daily for the duration of our study to gain an understanding of both their daytime and nighttime movements and habitat choices. Through our research, we are also compiling life history information regarding which native species toads interact with in the urban setting.

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Trapping

The trap-testing portion of our study was comprised of testing a trap known to have efficacy in Australia, for its capability in Southwest Florida. The traps utilize the animal’s biology against themselves by broadcasting the mating call from local male toads to attract both males and females. These traps have great potential as a tool for managing localized populations in Southwest Florida. The information gathered from the telemetry tracking element of the study directly informs the success of the trapping. By understanding the nuances of toad behavior we can utilize the traps more effectively.

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Diet analysis

The cane toad diet analysis involves looking at the stomach contents of cane toads from two locations in Naples, FL to better understand what wildlife is being effected through predation within urban communities. We are looking at both males and females, taking various measurements, and stomach contents are identified to the lowest possible taxonomic level.

Prepping Toads For Necropsy