Iguanas have a sweet tooth thanks to tourists

PARIS — Ecotourists feeding rock iguanas grapes on remote islands in the Bahamas have given them a sweet tooth and high blood sugar levels, researchers said Thursday, warning of unknown health effects on vulnerable reptiles.

The northern Bahamian rock iguanas living on the Exuma Islands are so addicted to tasty tourist treats that they rush to the beaches when they hear boats approaching.

“For a tour operator, it was a wonderful way to make sure you could see these animals and people would have these close, personal interactions,” said Charles Knapp, of the John G Shedd Aquarium in the United States.

Conservationists had already begun to worry that the non-native fruit, delivered to iguanas on skewers, made the large lizards less suspicious of humans and potentially vulnerable to smugglers for the pet trade. .

Hint in the poop

But those closely involved with the creatures began to suspect that the diets were causing even more upheaval. The clue was in their poo.

A rock iguana in the northern Bahamas that consumes the leaves and fruiting plants nature intended has feces that Utah State University scientist Susannah French compares to a “Cuban cigar – a bouquet of rolled up leaves”.

The excretions of those who had developed a taste for tourist grapes are a watery mess. This prompted researchers to look into the impacts of these high-sugar diets on iguanas’ bodies.

Their study, published in the Journal of Experimental Biology, first examined the effects of a high-glucose diet on common green iguanas in the laboratory.

“We were then able to provide glucose over time to mimic the type of intake these iguanas were receiving in the field,” French told AFP. They found that these animals had trouble regulating their blood sugar.

Harmful habit?

The researchers then traveled to the Bahamas and captured a total of 48 iguanas on four islands, half from populations frequented by tourists and the other half from more sheltered and remote outcrops.

Each iguana was given a glucose drink, and the researchers then monitored their blood sugar levels for nearly a day.

They found that those on the islands visited by tourists had the highest blood sugar spikes, with some remaining elevated for hours, while iguanas that never saw humans saw levels rise at a slower rate. and get back to normal faster.

Although the researchers concluded that the sugary diet physically affects the iguanas, they don’t yet know what impact this might have on their health.

“In other species, it would be a pathology. We would say yes, it’s diabetes if it were mice or humans,” said French, who said further research would investigate a range of potential health effects, from impacts on reproductive immunity.

Researchers are also investigating how their loss of appetite for their normal grazing of local plants might affect the wider environment of the islands.

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