American Toad (Bufo americanus)


     The male toad has larger front legs than the female toad for an easier grasp during amplexus, the position toads perform during sex.  The male toad also has rough pads on their first and second toes so mounting is more efficient. Although the male has longer front legs, the female tends to be relatively larger than the male. As you can see from the picture, the female on the bottom is much larger than the male. 


     In order for successful reproduction, the female must be attracted to a male.  This is done through mating calls. The male toads let off a series of high pitched calls by expanding the vocal sac under the chin.  Because of the constant expansion and reduction of this sac, males tend to have darkened chins.  The picture above shows the full expansion of the sac.  Below is a video of an American Toad mating call.  Video by Ryan M. Bolton, for more videos by Ryan, visit his website.


     The male will produce these sounds in varying months, from February to May, depending on the region, temperature and humidity.  It is believed that male toads will congregate into groups of up to 30 to increase the likeliness of a female responding to their calls.  A study showed that females tend to favor larger than average males.  Also, they choose males based on unique characteristics of calls.  If a female toad is not properly courted and does not get attracted to a particular toad, she may keep her eggs internally and not release them that season.  For this reason, the female toad is somewhat picky when choosing a mate.

     When a female chooses her mate, they engage in amplexus.  The male rests his toes right behind her forearms.  The female then releases her eggs and the male secretes a sperm-like fluid to fertilize the eggs.  Because this is done outside the body, it is called external fertilization.  A typical clutch size is anywhere from 3,000 to 20,000 eggs.  The eggs are arranged in a double string underwater.  They typically attach to vegetation for increased support.  A gelatinous transparent film covers the string for protection while the eggs develop into tadpoles.  Below, you can see the double string surrounding a parent toad. These eggs are typically 1-2 mm in diameter.
     All amphibians undergo metamorphosis, the abrupt physical stages of an egg to an adult. The developing eggs incubate for about 2 weeks until they hatch into a shallow body of water.  The young tadpoles have gills and a tail but no legs.  They are mostly herbivorous, feeding on plant material.   However, sometimes they feed on detritus and even dead tadpoles, classifying them as omnivores.Once they reach 12 weeks old, they start to feed on small insects.  They grow legs, lose their tail and are now called toadlets.  Growth continues and they eventually move to a terrestrial habitat until they reach sexual maturity anywhere from 1 to 3 years. The pictures below show the stages of metamorphosis; from egg to tadpole, tadpole to toadlet, and toadlet to a mature toad.