Invasions of the Godzilla variety are expected to be expensive, but new research has uncovered that the invasive spread of more humble amphibians and reptiles has cost us globally in the region of $17 billion since 1986. While smaller in size than their kaiju counterparts, these animals are able to cause devastation by spreading disease, destroying crops, and out-competing native species.
Infamous examples of reptile and amphibian invasions include the disastrous introduction of cane toads (Bufo marinus) to Australia. They were imported in 1935 as a means of controlling the cane beetle, but instead became a catastrophic invasive species in the country, destroying wildlife through coastal Queensland and making a nuisance of themselves in urban areas.
Then there’s Florida’s iguana fall, where each year the weather gets so cold that invasive green iguanas (Iguana iguana) drop from the trees as the cold weather sends them into a stupor. With no natural predators in the area, these animals have blossomed after first being introduced through the pet trade.
The catastrophic damage these and many other invasive reptiles and amphibians have caused amounted to at least $16.98 billion between 1986 and 2020, a new paper published in Scientific Reports found. As such, the authors behind it urge that greater effort is made to put in place and enforce policies that will limit the spread of existing invasive species, and any future invaders to come.
“Biological invasions by amphibian and reptile species (i.e. herpetofauna) are numerous and widespread, having caused severe impacts on ecosystems, the economy, and human health,” wrote the authors. “A greater effort in studying the costs of invasive herpetofauna is necessary for a more complete understanding of invasion impacts of these species.”
According to their calculations, that ~$17 billion bill can be split between amphibians, reptiles, and mixed classes, each accounting for $6.3 billion, $10.4 billion, and $334 million, respectively. However, among those figures are two key culprits: the brown tree snake (Boiga irregularis) and the American bullfrog (Lithobates catesbeianus).
A damning indictment of our perceived control over nomadic frogs, then, but the researchers recognize that not all invasive species are created equal (some are a lot more expensive than others).
“While we acknowledge that not all invasive alien herpetofauna will have tangible monetary impacts, greater research effort is required to distinguish the true absence of economic cost from gaps in cost detection, especially for those taxa with the worst known ecological impacts,” they wrote.
The cost of amphibian and reptile invasions needn’t be so high, say the researchers, as measures to limit the transport of invasive species and a better toolkit for their detection could help keep their spread to a minimum.
And at $17 billion over 34 years, they might have a point.