Saturday, March 23, 2013

Natural History of the Southern Toad (Anaxyrus terrestris)




Classification

Lissamphibia, Anura, Bufonidae
Species:
Anaxyrus terrestris
Identification: Toads belonging to the family bufonidae are easily identifiable by the presence of paratoid glands behind the tympanum. Adult southern toads can be easily identified in South Carolina by their pronounced cranial crests. The dark splotches on their dorsum typically contain two or three bumps whereas the similar looking American toad (Anaxyrus americanus) typically only has one or two bumps per dark patch. In addition the cranial crests on the american toad are less pronounced and do not connect to the paratoid gland as does the crest of the southern toad.
Southern toads are medium sized frogs and tend to be about the size of a walnut. Toads have a biphasic metamorphic life cycle, like most other anurans, with fully terrestrial adults. The specimen seen in the picture above is an adult as were all of the southern toads observed. The terrestriality of the organism is obvious in the bumps designed in moisture retention and short hind legs, useful for hopping along the ground. They are a common sight in this region to the point that when I asked a fellow classmate if he found anything under the log, he replied "no, just more toads." No other representatives of the family Bufonidae were found on either of the trips.
Like other amphibians the toads were found hidden under logs on both field trips as this is likely a good place to retain moisture during the middle of the day when the sun would easily desiccate an organism that is not proficient at retaining water. On the 20th the weather was more on the cold side for March, but later in the afternoon the temperature approached 65 or 70 degrees Fahrenheit. It was a nice sunny day but had rained a few days prior to the trip. As there were many fallen trees under which were moist, it is not a surprise that the toads were so easy to find.




1 comment:

Allison Welch said...

How big was this individual? Was it male or female? How big are walnuts??

Which bufonids can be found in the lowcountry?