Tiny frogs rock even tinier ‘G-strings’ for science | CBC Radio

How do you track a bunch of teeny-weeny frogs across the vast rainforests of South America? By putting teeny-weeny trackers on their teeny-weeny underwear, of course.

Biologist Andrius Pašukonis and his colleagues wanted to study the navigational capabilities of poisonous frogs that are too small for most animal tracking devices.

So he designed a Speedo-like harness that wraps around their back legs and props a tiny radio tracker on their backsides. The research team dubbed the invention “frog pants” — though Pašukonis says that’s “a bit of a misnomer.”

“My French colleagues like to call it a telemetric G-string,” Pašukonis, a senior scientist at Lithuania’s Vilnius University, told As It Happens host Nil Köksal.

“It’s a lot of fine motor skills and a lot of practice in handling tiny frogs and sewing little frog harnesses. But we go find them in the rainforest, and we catch them, and we put the tags on.”

WATCH | Scientist put tiny ‘pants’ on tiny frogs:

Scientist creates tiny ‘frog pants’ to track amphibian navigation

Stanford University biologist Andrius Pašukonis explains how and why he makes itty bitty Speedo-like tracking devices — called “frog pants” — to study extremely small rainforest critters.

Pašukonis was a PhD student at Stanford University in California when he designed the frog pants to study the spatial skills of three frog species that range from three to five centimetres in length — diablito poison frogs in Ecuador, and brilliant-thighed poison frogs and dyeing poison frogs in French Guiana. 

“The only way to study movements of animals is to be able to track them and follow them around, which nobody has managed to do or even tried to do with these tiny, tiny frogs in the rainforest,” he said.

“So that became my goal and challenge, where I spent a good part of my PhD trying different versions of different tags and different attachment methods, trial and error, to finally get to be able to put tags on and track them and study their behaviour.”

The frogs, he admits, didn’t particularly like the pants. But they didn’t seem to mind too much, and the team removed the trackers after four to six days. 

“Like any animal, they might scratch a little bit afterwards … like a dog with a new collar,” he said. “And then they just go on with their business.”

Tracker trials and and tribulations 

The design caught the eye of Richard Essner, a biologist at Southern Illinois University Edwardsville who studies animal locomotion, and has a particular interest in little frogs.

“Tracking small frogs with radio telemetry is not an easy thing to do,” Essner, who wasn’t involved in the Stanford research, told CBC in an email. 

About a decade ago, he says his lab attempted to use radio telemetry to track the movement of the threatened Illinois chorus frog using a transmitter attached via an elastic belt around the waist.

“Unfortunately, we had to abandon the study because we found that the transmitter apparatus was interfering with locomotion. If the belt was too tight, it caused abrasion. If it was too loose it slid down around the legs and left the frog immobilized and vulnerable to predation,” he said.

The frog pants, he says, seem to offer a solution to this conundrum. 

“After seeing this design, we may have to give it another go.”

Lea Randall, a Calgary Zoo and Wilder Institute ecologist who specializes in amphibians and reptiles, ran into similar obstacles while trying to track northern leopard frogs at a reintroduction site in B.C. 

Like the Stanford researchers, her team experimented with several different designs before landing on one that worked — a belt-like attachment with some “very stylish” smooth glass beads to prevent abrasion. 

“Unfortunately, due to the weight of the radio transmitters at the time we couldn’t study smaller individuals,” she said. 

“We didn’t use leg straps, but I can see the advantages of that to help keep the transmitters in place. The creative thinking and problem solving that goes into developing these kinds of studies always amazes me.”

However, she does have some concerns. Randall says transmitters should generally comprise no more than 10 per cent of an animal’s weight. Depending on the frog, the Stanford ones ranged from six to 12 per cent. 

“Although there was very low mortality in the study, I was concerned that some frogs experienced skin damage ranging from superficial abrasions to deep open wounds, but was encouraged that frogs seemed to quickly recover once the transmitters were removed,” she said.

Frogs are smarter than we think, says scientist

So if it’s such a hassle to track little frogs, why do it?

“To protect any species, it’s banal, but we need to understand what they’re about and what they’re up to,” Pašukonis said.

His team’s study — published late last year in the journal e-Life — compared navigational skills of male and female frogs. But Pašukonis says the massive amount of data they gathered from more than 300 frogs could have much wider implications.

“We usually work closely with the local conservation agencies and nature reserves, etc., to pass them on information … so it can be used also for conservation purposes,” he said. 

It’s also, he says, about scientific curiosity.

When it comes to animal cognition and behaviour, Pašukonis says frogs are understudied —  and he believes, underestimated — compared to birds and mammals.

The poisonous rainforest frogs, he says, may be only a few centimetres in size, but when they breed, they carry their tadpoles between 200 to 200 metres across the rainforest to find them the perfect puddle to grow in.

Then they turn right around, and make their way home again. 

“How could a little frog — frogs typically are not thought to be very smart — learn to navigate on such a big scale? And how do they find their way around more on a fundamental scientific level?” Pašukonis said.

“We’re uncovering that overall amphibians, for example, might be smarter or have more complicated cognitive abilities than we thought.”