Chorus in the marsh

By John Harrod, Manager, DuPont Environmental Education Center

All this week visitors to the DuPont Environmental Education Center have been greeted by the calls of the Southern Leopard Frogs. What started out as a grouping of frogs at the beginning of the boardwalk has now spread to a chorus throughout the marsh.

The Southern Leopard Frog is common throughout the coastal plain of Delaware, but is not found on the piedmont. They have dark round to oval spots that form irregular lines on the back and legs and there is a distinctive light spot on the center of tympanum (ear). They closely resemble Pickerel Frogs, but Pickerel Frogs have less rounded spots and no spot on the tympanum. Also, Pickerel Frogs have bright yellow orange coloration under their hind legs.

Southern Leopard Frog. Photo by John Harrod
Southern Leopard Frog. Photo by John Harrod

The advertisement call of the Southern Leopard Frog is typically a fast series of clucks often followed by a low growl that sounds like two balloons being rubbed together. It makes the call through paired lateral vocal sacs on each side of the head.  DNS staff member Jim White reports that the leopard frogs at DEEC and other coastal areas of Delaware call somewhat differently than the typical Southern Leopard Frogs. Along with the growl the DEEC or coastal leopard frogs emit clucks singly or in a slow succession instead of in a fast series like the typical Southern Leopard Frog.  This “coastal” call variation can easily be confused with the call of the Wood Frog; however Wood Frogs do not growl and typically do not breed in marshes that are of any distance from woodlands. The call of the “coastal” Southern Leopard Frogs is so unique that White and fellow herpetologist Nate Nazdrowicz are investigating the genetics of this population to see if it is a separate subspecies.

Southern Leopard Frog vocal sac. Photo by John Harrod.

Stop by the DEEC to listen to the frogs as they should continue to actively call for another week.

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