Worldwide, scientists have documented the extinction of 32 species of frogs in recent decades, and 200 more are in decline- including some species found in our own backyards. Like canaries in a coal mine, frogs and toads are sensitive to pollutants and changes in their habitat. They have extremely permeable skin that allows chemicals- gas and liquid- to easily penetrate their bodies. This is why they are excellent "sentinels" of the health of our environment. By knowing where in our environment frogs are flourishing and where they may be vanishing, researchers can direct their efforts to protect key habitats, ensuring not only the continued vitality and diversity of amphibians, but of our own quality of life.
To better understand the link between frogs and the overall well being of our environment, the Hillsborough River Watershed Alliance created the Frog Listening Network. Scientists from public agencies, universities, and local organizations plus thousands of everyday volunteers just like you help form the Frog Listening Network.
Why are frogs food "sentinels" of the environment?
Although frogs and toads spend most of their lives on land, their eggs must be deposited in water. After being born and maturing in the water, they move onto land to live and then go back to the water to reproduce. This dependence upon both land and water to complete their life cycles makes frogs and toads excellent barometers, or sentinels, of environmental health. Likewise, their sensitive skin makes them susceptible to changes in the environment, such as by pesticides and herbicides, which is another key to their ability to serve as indicators of the environment.
Why is watershed health important to frogs?
Frogs need healthy watersheds because they depend on them for producing offspring. Polluted water may cause some tadpoles to grow abnormally or not survive. Some declines in certain frog species populations may indicate poor water quality. Frogs have adapted to the normal hydroperiod, that is, the normal fluctuation of wet and dry periods in their breeding grounds. Changes in water quality or quantity, or timing of precipitation could affect their breeding cycle.
Why is it called the Frog "Listening" Network?
With the arrival of warm weather, frogs and toads gather near ponds, lakes, streams, ditches, or even swimming pools, usually on rainy summer evenings to call to their mates. While they are easy to hear, frogs and toads are often difficult to spot visually. They are usually found in dense vegetation, they can sometimes be quite tiny, and some are very good ventriloquists. They also like to make their appearances during weather conditions that most people like to avoid such as while it is raining or after dark. So it is easier to listen for frogs rather than try to see them. This can be difficult to get used to if you tend to like bird watching on clear and beautiful mornings. However, we encourage you to give frog listening a fair chance because we are convinced that once you identify your first frog you will be hooked. The sound of a deafening chorus of five species of frogs is an unforgettable experience. It is a fun and exciting activity that the entire family can enjoy while contributing to environmental conservation.
Where do frogs come from?
A frog begins life as an egg deposited in a body of water. The egg hatches into a tadpole after 6 to 21 days, depending on the species. About 7 to 10 days later, the tadpole begins to swim and feed on algae. Over the next 6 to 9 weeks, the tadpole gradually changes, losing its long tail and sprouting arms and legs. The "froglet", as it is now known, begins to eat plants and insects floating in the water. By the time it is 3-4 months old, the tadpole has absorbed its stubby tail and abandons its watery world to begin its adult life on land as a full-grown frog.
The only species in west-central Florida that does not grow up outside of an egg is the non-native Greenhouse Frog. Similar to birds, tadpoles of this species grow while still inside the egg. Only when the tadpole has changed into a frog does it escape from the egg to venture onto land.
What kinds of frogs live along the Hillsborough River?
Florida is blessed with a wide variety of frogs and toads, about 28 species in all. Of those 28 species, nearly two dozen are found in the Hillsborough River watershed such as Green Tree Frogs, Eastern Spadefoot Toads, Bull Frogs, and Oak Toads. Three introduced (non-native) species including the Cuban Tree Frog, the Greenhouse Frog, and the Marine Toad are also found within the watershed. The Greenhouse Frog appears to be relatively harmless. However, the Cuban Tree Frog and the Marine Toad have both been expanding their ranges throughout the river basin each year and are known to consume and compete with native species as tadpoles and adults.
Why do frogs sing?
Male frogs initially sing to announce their presence to females of their species. These serenades typically occur on rainy spring or summer evenings when the barometric pressure is low and falling. The males then gather near a body of water and begin croaking to woo the females into breeding. Each frog has its own unique call that range from sounding like dogs barking off in the distance to broken banjo strings, dripping water, and various animal sounds like turkeys, baby chicks, and sheep. The impressive chorus created by many frogs singing in unison is a signature sound of summer in Florida.
What is the difference between frogs and toads?
In general, frogs spend most of their lives in or near water, while toads are found commonly on land. And frogs usually have moist, slimy skin while toads tend to have dry, bumpy skin. No matter what the myth says, frogs and toads cannot give you warts!
Are all frogs poisonous?
All frogs have some degree of toxicity in their skin. However, most species' poisons, except the Cuban Tree Frog and the Marine Toad, are not strong enough to affect humans. We suggest that you wash your hands thoroughly after handling all frogs just to be safe.
What do I have to do as a volunteer?
Volunteers are asked to commit 30 minutes once a month to listening for frogs and toads at a site that is convenient and easily accessible. We will also have occasional fun outings where we will go out as a group and collect data. The data will be based on an estimate of the number of male frogs that are calling during the 30-minute period. You will then submit the data you collect to the Hillsborough River Watershed Alliance so that it can be analyzed by local biologists. It's that easy!
What happens to all data I collect?
Along with additional environmentally important data collected by others, the frog data are compiled into an annual report that is made available for use by the Florida Fish and Wildlife Conservation Commission and the National Amphibian Monitoring Program. These data help to paint a picture of the health of the environment.
When are Frog Listening Network trainings held?
Our trainings are held on a monthly to quarterly basis at locations throughout the Tampa Bay area. We will make public announcements of upcoming trainings. However, please contact the HRWA to make sure you know when and where we are meeting. We are able to conduct trainings for your special event upon request and availability.
How can I help protect frogs and other Florida wildlife?
There are many ways to help protect west-central Florida wildlife including frogs and toads.
- Create a wildlife-friendly garden that includes old pots or containers where frogs can hide.
- Provide a water feature such as bird bath that can serve as a home base.
- Landscape with plants that attract insects that frogs can eat. Do not spray pesticides in the water for mosquito control unless using a chemical that is safe for vertebrates.
- Reduce or eliminate the use of lawn pesticides and herbicides by planting Florida Friendly plants.
- Preserve temporary ponds that occur on your property such as potholes and other areas where water is retained only during the wet season. They are important breeding areas for frogs.
- Help control non-native amphibian species by placing them in sealed plastic containers and putting the containers in your freezer. Because frogs and toads are cold-blooded (their body temperatures adjust to the outside temperature), they will painlessly go to sleep once their body temperature becomes cold enough. This has been determined to be the most humane way to eliminate non-native species.It is our recommendation that you keep the containers in your freezer for at least one week because some frogs and toads may be revived after only short freezing periods.
- Become a frog listener!