PROVIDENCE, R.I. – Wait … is that frog blue?
That’s what many might question after seeing a rare blue-green bullfrog spotted last weekend in Rhode Island by the Ragosta family, the state’s Department of Environmental Management said.
Some of the Ocean State’s frog species can occasionally exhibit rare blue coloration. This pigmentation, known as axanthism, is caused by a lack of the xanthophores and carotenoids that cause yellow pigmentation in the skin, the agency said. This means that typically green frogs will look blue.
Wildlife technician Liam Corcoran said it is not known exactly how the blue coloration is inherited genetically.
“However, the blue coloration has been observed in many species in the same family (Ranidae) including green frogs, leopard frogs (Lithobates pipiens), and bullfrogs,” she said in a prior newsletter released by the state.
Corcoran says the research suggests green frogs are the most common species to exhibit this blue trait.
While blue frogs have been reported throughout New England, especially in Massachusetts and Connecticut, only two observations of the frogs have reported to the Rhode Island Department of Environmental Management since 2019, according to a 2021 report by the wildlife division.
Rhode Island has the highest diversity of amphibians in the U.S., wildlife officials say, with 18 species in just 1,200 square miles.