Natural History - Gastrophryne carolinensis

The Eastern Narrowmouth Toad (Gastrophryne carolinensis) is our only local species in the family microhylidae. Microhylids are all in the category of narrow-mouthed frogs and members of this group have characteristically plump bodies with short limbs and a pointed head. The majority of these frogs also have a inconspicuous skin fold across the back of their head which helps wipe away insects that may attack their eyes. Despite being called a toad, G. carolinensis has smooth skin. They are most likely called toads due to their fat bellies or rough appearance of their skin due to the coloration. The Eastern Narrowmouth Toad is a relatively small frog measuring an average of 1-1.5 inches long. Their color is usually grey or brown, but this can change from day to day or depending on the mood of the organism, and their under side is usually very blotchy. 

The images above show the extreme variation in G. carolinensis coloration.


The main source of food for the Naurowmouth Toad is ants, but they will also eat a variety of invertebrates. The range of G. carolinensis is throughout the Southeast with the exception of the higher elevations of the Appalachian Mountains. Their habitats can be variable but they are usually found under logs in woodland areas. During the summer, Narrowmouth Toads retreat to temporary wetlands, such as ponds, puddles, or ditches to breed. Calling is initiated by a heavy rain but males are often difficult to locate during mating because they call completely submerged by mud or water other than their snout. The mating call has been described as a nasally, sheep-like "neeeeeee" sound. Male Narrowmouth Toads secrete a sticky substance that helps him stick to the female's back during amplexus. After mating, the female lays eggs which float on the surface of the water and hatch after 1-2 days. After hatching it takes about 20-70 days for the tadpoles to metamorphose. The most important stress Narrowmouth tadpoles endure is the risk of desiccation due to the rapid drying up of the larval pool. Adult Narrowmouth Toads spend their lives in the vicinity of the temporary wetland awaiting a large rain. In general, these frogs have a very small home range which has been found to be about a 5-m quadrant. The major predators of G. carolinensis include a variety of water snakes which they avoid by burrowing or seeking cover in a log or under a rock, skin secretions, or by their nocturnal lifestyle. Their narrow mouth is ideal for their diet of small invertebrates and their short limbs and stout body are an advantage for burrowing. Although these unique frogs are very seldom seen, they are important because they add diversity to our local anurans.