Ribbet. Ribbet. Thank goodness.
Ellison Creek flowing off the Mogollon Rim recently got another dose of Chiricahua Leopard Frogs, a natty, green amphibian who croaks through the night — a damp canary in Rim Country’s environmental “coal mine.”
The Chiricahua Leopard Frog heads the local list of vanishing amphibians, a trend experts connect to pollution, climate change, changes in the thickness of the ozone layer and other problems in the beleaguered riparian areas on which they depend.
“The whole ‘canary in the coal mine’ role of frogs comes from how sensitive they are to environmental change,” said Mike Srebl, leader of the Chiricahua Leopard Frog Recovery Program for the Arizona Game and Fish Department.
Biologists recent released some 1,400 frogs and tadpoles into the creek to augment the existing population there. Reared at the Phoenix Zoo until they were big enough to have a better chance to survive, the release represents the latest effort to help a once widespread frog hop up the muddy slope of extinction.
The project has also formed rare links between biologists and local ranchers, who have become enthusiastic advocates for the grinning green critters. Although cattle grazing along streams has contributed to the decline of frogs throughout the West, stock tanks also provide a refuge for frog species where they’re often safe from other predators.
“It’s so important to have the ranchers at the table,” said Srebl. “When it comes down to it, I’ve met very few ranchers not interested in being good stewards — the trick is it just takes a little more work.”
A rancher whose grazing allotment includes Ellison Creek has been an enthusiastic supporter — and even showed up to release the first batch of frogs into the creek. That cooperation has enabled biologists to figure out how to use fencing and herd management to keep the cattle out of ponds and stream stretches important to the frogs, said Srebl, especially when the state biologists found federal grants to pay for needed fencing.
“It really turned into a win/win situation,” said Srebl.
Unfortunately, the colorful amphibian hasn’t encountered many win/win situations in recent decades, with a host of changes contributing to a dangerous decline.
Even before the recent, decade-long drought dried up many streams and springs, the frogs had to cope with human-caused changes that have degraded an estimated 90 percent of the state’s streams, rivers and lakes.
The Chiricahua Leopard Frog is on the worrisome leading edge of a baffling trend, the steep, worldwide decline of frogs and salamanders. The U.S. has 230 amphibian species, including 90 toads and frogs.
Most frog species are declining rapidly. Experts have also noted a dramatic increase in the number of frogs suffering from mutations, many born with extra or missing limbs or other malformations. Studies have identified a bewildering array of possible causes, but the loss of vital riparian habitats accounts for about half of the decline, particularly streams and associated wetlands.
Most frog species have also been impacted by the introduction of non-native predators, like crayfish, bass, trout, sunfish and others.
Ironically, many native frogs have also suffered from the rapid spread of tough, voracious bullfrogs — which eat nearly anything they can get their big mouths around and can hop for miles across dry ground to colonize a new pond or stream.
In addition, studies have shown that the amphibians are vulnerable because of their complicated life cycle, which includes stages of being encased in underwater eggs, the water breathing tadpole phase and their thin-skinned adulthood. Many frogs can breathe through their skins, critical to getting through the winter buried in the mud — but that means that pollutants can also pass through their skins.
Studies have also shown that increased ultraviolet radiation, perhaps due to a thinning of the Earth’s ozone layer caused by certain pollutants, might account for the rise in mutations, which affects 60 percent of the young of some frog species.
Other factors include pesticides and water pollution caused by septic tanks and heavy metals leaching out of mine tailings.
Other researchers have focused on the spread of viruses, bacteria and fungi, which have heavily impacted some species.
The captive breeding and release program for the dwindling Chiricahua Leopard Frogs is intended to reverse the trend toward extinction.
The 5-inch frogs can live for 18 years, favoring ponds, springs, streams and even stock ponds at an elevation range of 3,200 to 8,800 feet. They exist in scattered populations throughout central, east-central and southeastern Arizona and on into New Mexico, northwestern Sonora and northwestern Chihuahua in Mexico.
The zoo has been cranking out tadpoles and froglings for a decade. The captive frogs lay masses of eggs in May, which hatch and grow into healthy tadpoles over the summer.
The late summer/early fall release should give the critters time enough to adapt to their new surroundings before the freezing temperatures of winter prompts them to burrow into the mud where they go into a state of hibernation for the winter, usually in pools of water deep enough that they won’t freeze to the bottom.
Stebl noted that in addition to the seemingly healthy population in Ellison Creek, biologists are monitoring populations in East and West Clear Creek, near Camp Verde and in several stock tanks in Rim Country.
In some cases, biologists captured the last few surviving frogs in different areas of the Rim as the drought dried up their water sources, to support the captive breeding program. They hope to reintroduce the frogs to some of their former homes if the drought eases and water levels return to something approaching normal.
Unfortunately, the frogs remain embattled by a host of large scale changes, said Stebl.
And just as miners once took canaries down into mine shafts because the birds would die from the buildup of lethal gases before the humans could sense the gas, so the dwindling amphibians serve as a warning about the state of vital riparian areas — on which an estimated 90 percent of wildlife depend for some stage of their lives.
“There are many reasons that amphibian populations have declined worldwide, but to go back to the canary in the coal mine analogy — what the canary is telling us is that we’re not being very good stewards of our land.”