Monday, October 10, 2011

147 Years of Invasive Herps

Living in the Chicago suburbs, between a metropolitan concrete desert and a vast agroecosystems, you don't expect to find an exotic herpetofauna. However, over the years people have brought me a variety of released pets. The occasional boa or iguana is to be expected, but perhaps the most unusual was an acquaintance that pulled his pickup into my driveway and said, "...are there lizards in Illinois," of course I replied in the affirmative. He removed a shovel from the back of the truck, on the blade was a very large, road killed Tokay Gecko. He had found the lizard on a road that runs through miles of cornfield, and the nearest human dwelling was at least a mile away.

In a recently published paper Kenneth Krysto and colleagues confirm three intercepted and 137 introduced amphibian and reptile taxa that have been found in the state of Florida. Remarkably only two (1.34%) were the result of biological controls, four (2.68%) came from zoo escapes; 18 (12.08%) came from cargo; and totally unsurprising, 125 (83.89%) came courtesy of the pet trade.

Florida holds the record for having the largest (56 taxa) established non-indigenous herpetofauna in world, Hawaii is a distant second (31 taxa).The origins of the non-native species spanning span the globe, and includes species from Australia, Oceania and Indonesia, Asia, the Mediterranean, Africa, Madagascar, South America, the Caribbean, as well as other states.

The literature suggests that about 10% of non-indigenous species that are transported to a new area actually become introduced, and 10% of those become established, and 10% of those become pests. This model was developed for British plants and animals, but exceptions to the rule are introduced birds in Hawaii, where more than half of the introduced species became established. The number (43 species) of non-indigenous lizards in Florida is spectacular, considering Florida has only 16 native lizards. This may be due to a combination of their popularity in the pet trade, but also the climate and microhabitats available in Florida.

This report is likely to have consequences for the pet trade and exotic animal business. It also raises the issue of ignoring non-native species or trying to do something about them. The flora and fauna at any given location is the result of co-evolved species, species that have adapted to each other over geological time. Humans have altered those communities in the blink of an eye, with little regard for the consequences. Ignorance is an enemy and released pets that become established can also become pests, and some are capable of causing serious damage to ecosystems. This paper makes for fascinating reading.

The African Clawed Frog was intentionally
introduced into Florida in 1964 by an animal
dealer. JCM
Krysko, K. L. et al. 2011. Verified non-indigenous amphibians and reptiles in Florida from 1863 through 2010: Outlining the invasion process and identifying invasion pathways and stages. Zootaxa 3028: 1–64.

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