"Sometimes I just can't wait till I get back to the lab to do the chemistry, and I want to get an idea if there is something nasty," she said.
Clark's habit isn't quite as rare, or as crazy, as it may sound.
Research opportunities in remote tropical forests are often limited, and only so many specimens can be taken back to the lab for detailed chemical analysis.
"[But] I don't recommend this," the biologist cautioned, "because if you lick the wrong frog it can be very bad."
The World Conservation Union (IUCN) estimates that one-third of all amphibian species are currently threatened with extinction.