If you’re by a desert spring in far northwest Arizona or southeast Nevada and hear a low chuckle followed by what sounds like fingers rubbing on a balloon, you may have stumbled upon a relict leopard frog.

These olive-green to light-brown frogs can be told apart from their lowland cousins in southern Arizona only by genetic analysis.

Relict leopard frogs originally lived in springs, marshy backwaters, and side canyons along the Virgin, Muddy, and Colorado rivers. Dam building, marsh draining, and non-native predators drastically reduced their range, and their numbers shrank dangerously low.

In fact the species was believed extinct – until three populations were found in Nevada in the early 1990s.

That led a conservation team, including the U.S. Fish and Wildlife Service and Arizona Game and Fish Department, to spearhead recovery efforts and a captive breeding program at the University of Nevada Las Vegas.

A ten-year conservation agreement calls for managing the habitat of remaining natural sites – along with releasing captive-bred animals at new sites.

Relict leopard frogs now inhabit twenty sites - including three in Arizona where they are doing well.

Although no one knows exactly how many of them there are, their situation has been judged healthy enough to remove the species from the list of candidates for protection under the federal Endangered Species Act.

Someday, the chuckling calls of these frogs may be heard more often.