What we normally think of as frog calls is the “advertisement call” 
made by males during the mating season to attract females. Those are the calls listed on this page, and the call that this little Spring Peeper is making with his single vocal sac. Males can also make an “aggressive or territorial call” to keep other males out of their mating area. If a male happens to mount another male or a female that is not ready, the offended frog will make a “release call” to make the offender realize his mistake. And finally, when a frog is attacked by a predator or approached by a human he or she may let out with a “distress call.”
To make identification of frog calls even more challenging, the calls will vary with temperature and humidity changes, by area, and even the inhabitants of single ponds may have unique frog call dialects! Can you learn all the frog slang at your pond?
Click on the names to hear the advertisement frog calls
Click on the pictures to see an enlarged copy
Which frog call sounds like a banjo string being plunked?
Can you identify the frog calls that sound like whistling?
Find the frog calls that are trills. Which one is most melodic?
Here is an additional excellent Frog Calls site.
Frog Calling Phenology (timing)
When do the frogs and toads start to call? This will help you practice before you go out to the pond to monitor.
Late Winter/Early Spring: Wood Frogs; Spring Peepers; Southern Leopard Frogs; Chorus Frogs; Pickerel Frog; Crawfish Frog
Spring: American Bullfrog; Dwarf American Toads; Blanchard’s Cricket Frog
Late Spring/Summer: Fowler’s Toad; Green Frog; All the Treefrogs
Anytime after a heavy rain: Narrow-mouthed Toads, Spadefoots