May 15, 2013 —
It’s been a couple of weeks now that I have heard a lot of trilling from nearby lakes and wetlands. The first thought from someone not familiar with the local habitat may be that there is a swarm of crickets or other insects that frequent waterways during spring. This is not the case however; the trilling is the courtship call of the American Toad (Anaxyrus americanus). This is a recent scientific name change as the old genus name was “Bufo”. Calling toads can be heard here: http://www.twcwc.com/toadsong.html.
American toads start courtship calling in our region by May and continue into June. It is the male toads that can be heard calling as they try to attract a female for mating. Their call is loud and can be heard far off. If you are within 20 feet or so of a few males calling, most other sounds are drowned out. American toads do not have to open their mouth to emit their loud calls. They will expel a lungful of air through the larynx and into the vocal sac below their jaw. The sound resonates within the vocal sac and causes it to be amplified and propagated through the air. The call trills are usually 30 to 40 Hz in frequency and can last for over half a minute.
After the end of breeding season, most of the toads will disappear from the aquatic habitats as American toads do not need a body of water during non-breeding times. The first tiny toad offspring may be visible in early July as they emerge from the water as freshly metamorphosed toadlets. If you happen to handle an American toad, wash your hands afterwards as the parotid glands (the big warts behind each eye) emit a toxin which can make humans ill if ingested. American toads and other amphibians will be heard for a few months. Sit back and enjoy the spring serenade.