DNR: A frog species that mysteriously disappeared from the Tri-State in the 1980s is back

A species of prairie-dwelling amphibians that disappeared from the Angel Mounds Historic Site a generation ago has been reintroduced there, Indiana state officials said this week.

The crawfish frog , endangered in the Hoosier State, is back following an effort led by the Indiana Department of Natural Resources and Angel Mounds.

History of crawfish frogs at Angel Mounds

The announcement of the frog's return comes two years after a conservation effort began to bring them back to the archaeological site that was home to the Mississippian culture of Native Americans from 1100 to 1450 AD.

Officials say the crawfish frog likely was at the site during that period, as well, and remained in place until the mid to late 1980s, when they "vanished suddenly and mysteriously, possibly triggered by an extended drought," according to a news release.

How big are crawfish frogs and what do they sound like?

Adult crawfish frogs grow to "the size of a fist" and have a distinguishing spot pattern and loud croak. One state nature website describes their call as "a deep, loud, snoring 'gwwaaa' which can be heard from a considerable distance."

"As they call, their large, lateral vocal sacs vibrate the water surface. A number of males calling in chorus sounds like pigs during feeding time," one site says.

They also spend much of their lives underground.

“Indiana only has two robust crawfish frog populations remaining in the state,” said Department of Natural Resources Herpetologist Nate Engbrecht. “The recovery effort at Angel Mounds is somewhat unique for being a historic restoration project — a biological one — that aims to recover a historic component of the site that has been lost.”

Re-introducing the crawfish frog to Angel Mounds

A news release described the program to bring the frog back to Angel Mounds this way:

"A habitat suitability study conducted by DNR determined Angel Mounds has the ideal environmental conditions to support crawfish frogs. In particular, the analysis identified several small ponds in the northwest corner of the site that fill with water after each winter but dry out during the summer. The ponds were formed centuries ago from 'borrow pits,' or large holes left after Native Americans built the mud wall at Angel Mounds."

So in March, eight crawfish frog egg masses were removed from a large population in Greene County, Indiana, and relocated to a pond at Angel Mounds. They were placed inside cages for protection.

Tadpoles everywhere!

The result: Thousands of tadpoles filled the ponds within weeks. By early July, they were frogs, hopping around the area.

"Crawfish frogs take two to three years to reach sexual maturity, meaning that the frogs that were moved to Angel Mounds this spring will not return to the pond from where they hatched to mate until 2026," officials wrote in a news release. "In the meantime, the DNR plans to move additional egg masses to supplement the local population during the spring of 2025."

This article originally appeared on Evansville Courier & Press: DNR: A frog species that mysteriously disappeared from the Tri-State in the 1980s is back