|
Your Neighbor: The American Toad
By Janey Kramlik, Animal Keeper, Brandywine Zoo
If you have come across a toad in your yard or in the local park recently, chances are that it was an American toad (Bufo americanus) because it is the most widespread toad species in North America. Don't worry, these toads are helpful little insect controllers and you won't get warts from touching one (just be sure to wash your hands thoroughly if you must touch one since they excrete toxins through their skin)!
The American toad is found throughout the United States and parts of Canada, including right here in the Delmarva Peninsula. In the wild, these toads can be expected to live from less than 1 year to 10 years. The average lifespan of an American toad in captivity is 5 years. American toads range in size from 2-3.5 inches in length from nose to vent, and have short, stout bodies. The top of these toads is usually brown in color with dark brown spots and 1-2 warts in each of the dorsal spots. Their underbelly is white or yellow and the throat of the male is black, rather than the tan throats found in females.
Since these particular toads easily adapt to a variety of surroundings, as long as there is a water source, they have been able to successfully colonize where land has been developed for human use. American toads require a water source for laying their eggs in, and dense vegetation or ground covering to hide and hunt in. Males, which are smaller than females, will emerge from their winter hibernation underground and seek out an appropriate breeding territory. Once the male has found a suitable breeding area with a nearby water source, he will begin to call for a female. The call of each species of toad is unique. The American toad call is a 5-30 second long high pitched shrill produced by a single vocal sac. This call can be commonly heard from March to June, and sometimes into July. Even though American toads are nocturnal, or active at night, during peak breeding season, the males will call during the night and day to increase their chances of a female choosing them. After breeding, the female will lay her 4,000-8,000 eggs in two rows in long spiral tubes of jelly near vegetation in water. The eggs take 3-12 days to hatch into tadpoles, depending upon the temperature. The tadpoles have gills to help them breathe in the water, a tail to aid in swimming since they have no legs yet, and a layer of toxic chemicals to help protect them from predation. After 40-70 days, the tadpoles develop into adults with lungs and legs. American toads reach sexual maturity at 2-3 years.
American toad tadpoles are mainly herbivores, eating aquatic vegetation, such as algae, but will also eat decaying fish and even occasionally other tadpoles. Adults are carnivores, feeding on a wide variety of insects, invertebrates, and small mammals. Toads do not drink water; they actually soak in the water and absorb the moisture through their skin. It is for this reason that they are extremely susceptible to toxins and pollutants, such as fertilizer and insecticides in water.
The largest restricting factor to the lifespan of American toads is predation from other animals. Although American toads excrete a powerful toxin from glands on their backs that is capable of hurting and even killing some animals, there are animals that have found ways around this toxin. Eastern hog-nosed snakes, water snakes, garter snakes, occasionally ducks, crows, screech owls, raccoons, and striped skunks easily eat American toads. Another threat to these toads is humans. Cars kill hundreds of American toads on roadways during peak breeding time. Pollutants and acid rain can deform and even kill these toads as well.
Want to help these toads? Here are a few things that you can do to for American toads:
- Avoid touching toads when you find them. Anything on your hands can be absorbed into the toad through its skin and be detrimental to the toad.
- Keep pets from catching toads. This is for the safety of both toad and pet.
- Set up "toad huts" in your garden, yard, or ground covering using pieces of log, sticks, plants, or commercially available products (Yes, there are actually "toad huts" for sale!).
- Watch for toads on wet or dark roadways, especially during peak breeding times.
- Restrict your use of pesticides and fertilizers.
- Check out your local wildlife refuge, nature center, or come to the zoo to learn more about American toads.
- Participate in the Association of Zoos and Aquariums (AZA) Year of the Frog events by checking out their website www.aza.org.
|
