Frogs and Toads of Polk County
The call of two tiny frogs in early March is a sure sign that spring is just around the corner. From March to August throughout Iowa the wetlands, ponds, and waterways are filled with the sounds of male frogs calling for mates. The Spring Peeper and Western Chorus Frog start calling before all of the snow has melted followed by many others until the bullfrogs end the amphibian chorus in August. An outdoor experience is not the same without hearing these slimy, smooth skinned creatures in the background.
There are 16 species of frogs/toads that breed and spend their lives in Iowa. You can find seven of these here in Polk County.
Species Found in Polk County
Listed below are the species of frogs and toads found in Polk County along with a description of their calls. They are listed in the order they are heard during the year. Keep in mind that a mild or severe winter will bring them out of hibernation earlier or later depending on the water temperatures.
Western Chorus Frog
This little frog is about 1-1/4 inches long and is usually a pale green with three brown stripes down its back. Listen for this frog’s call from early March to late May. It sounds like a person dragging their fingernail along the teeth of a comb.
The spring peeper is one of the smallest frogs in Iowa and is about 1-1 1/2 inches long. There is usually a distincitve "X" on it's back. Listen for this frog's call from April through May. It's call sounds like "peep, peep, peep!"
Northern Leopard Frog
Around April 1st, one of the most handsome amphibians emerges and makes its presence known. They are about 3-1/2 inches long. Its greenish back and lighter colored belly are the background for a series of elongated brown spots. The call is a rattling, uneven snore similar to the sounds of a finger rubbing on an inflated balloon. This frog can be heard through the month of June.
Gray Tree Frog
As its name suggests, this frog is gray, but can also be brown, black, or green depending on the color of its surroundings. There are actually two different species of gray tree frogs- Cope’s and Eastern- but even scientists have a hard time telling them apart. Look for the expanded toe pads that aid in gripping vertical surfaces like plant stems and leaves. The call is a bubbly trill, which reminds one of singing underwater. They can be heard from April thru June.
Cricket frogs are gray, black or brown, with a slightly darker triangle between the eyes. They are small, reaching a length of about 1-3/8 inches long. The cricket frog sounds like two steel balls being rapidly clicked together. Listen for this frog's call from mid-April through July.
The bullfrog is the largest of all frogs in the state. The bullfrog was once found in the southern and eastern parts of the state only. Introduction by humans has spread its range to the entire state, sometimes to the detriment of other amphibian species. It attains lengths of 6-8 inches. It is dark brown or olive-colored with patches/streaks of black. The underside is white. You can hear bullfrogs from May until mid-August, and their call sounds like a foghorn or bull off in the distance.
Unlike other amphibians, toads have dry rough skin. This rather large toad grows to a length of nearly 4 inches. It can be distinguished from other toads by its spotted belly. Others have a solidly colored underside. It's the only toad found in Polk County. This toad makes a loud, melodious trill lasting as long as 30 seconds. Listen for it from April thru June.
The Lifecycle of a Frog
All amphibians lay their eggs in water. When the eggs hatch, tadpoles emerge and live an aquatic lifestyle. A few short weeks after hatching the tadpoles undergo metamorphosis. Soon the adult emerges and learns to feed and survive as a partially terrestrial animal. The following spring will be its time produce a clutch of eggs.
The amphibians, frogs and salamanders, have been on earth longer than humans. Their presence is a good indicator to use toward the health of our environment. Sadly, the populations of these little creatures are declining, and researchers don’t completely understand why. Preserving habitat is a must if we want to continue having these important members of the food chain. The next time you’re out in a natural area, listen for the calls of these special animals.
Other Frogs and Toads of Iowa
Outside of Polk County, look for the species of frogs and toads that inhabit the state. They are:
- Crawfish Frog
- Great Plain’s Toad
- Green Frog
- Pickerel Frog
- Plain’s Leopard Frog
- Plain’s Spadefoot
- Southern Leopard Frog
- Woodhouse’s Toad
Iowa Herpetology - This site is designed to introduce you to the herpetology of Iowa. Contains pictures, information, and distribution of frogs and toads in Iowa.