The risk of exotic reptile imports invading Florida

Scrub python from the Bronx Zoo in New York City.The recent explosive growth in the exotic reptile trade in Florida has raised serious concerns about species establishing in the wild and causing harm to ecosystems and human safety. To help us understand which exotic reptiles pose the greatest threat, researchers have identified risk factors that make certain species more likely to invade.

Physical Risk Factors: 1) Temperature match between a species' native range and Florida;

Social Risk Factors: 2) Low sale price; 3) Poor manageability (defined as a species’ maintenance cost, aggressiveness, proneness to escape, and venomousness). Both these factors imply that an owner would be more likely to release a reptile.

Biological Risk Factors: 4) Species belonging to specific taxonomic orders;

Lead researcher Ikuko Fujisaki and fellow study authors identified these risk factors by looking at 68 reptiles, which already have either successfully established in the wild or failed to do so. They developed a model to see what common factors best explained those outcomes.

The scientists then took their research a step further. Using these risk factors, they conducted a formal assessment of the threat posed by 35 of the most commonly imported exotic reptiles, which have yet to establish in the wild. Based on their assessment, they identified 8 species of lizards and 4 species of snakes as potentially successfully invaders.

They further assessed those twelve species based on their potential threat to the ecosystem and human safety and their ability to spread quickly. They found that 6 species posed a significant risk based on those criteria.

These high-risk species include: African rock python (Python sebae), puff adder (Bitis arietans), anaconda (Eunectes murinus), scrub python (Morelia amethistina), Asian grass lizard (Takydromus sexlineatus), Senegal chameleon (Chamaeleo senegalensis).

The authors recommend that future research efforts extend their risk assessment to all reptile species imported to the state. They write,"

"Applying this risk assessment model to screen imported species would allow us to develop a list of ‘‘risky reptiles’’ for which trade would be restricted to eliminate risk of establishment…Applying this approach to imported reptiles could focus attention on relatively few species in a confined geographic area where the climate matches that of their native range."

This work is particularly timely. Lawmakers in Congress are currently considering a bill that would ban the importation of nine species of snakes including Burmese pythons (Python molurus bivittatus) due to public concerns about their invasion threat. 

--Reviewed by Rob Goldstein

Fujisaki, I., Hart, K., Mazzotti, F., Rice, K., Snow, S., & Rochford, M. (2009). Risk assessment of potential invasiveness of exotic reptiles imported to south Florida Biological Invasions DOI: 10.1007/s10530-009-9667-1