Iguanas are a common and generally welcome site in the Galapagos Islands. In fact, the archipelago is literally crawling with them in some places. But last month, a very unusual iguana sighting raised serious alarm bells in the Galapagos conservation community. A green iguana, which is native to mainland South America, was spotted and captured. There is no word yet on the exact location of the incident, but based on the photographs it appears to have been near a beach somewhere on one of the inhabited islands.
Scientists believe that the ancestors of modern Galapagos iguana species arrived hundreds of thousands of years ago aboard floating rafts of vegetation from the mainland. Over time, those early arrivals evolved into the four different endemic species of iguana found in the islands today, including three species of land iguana and the marine iguana, the world’s only seafaring lizard.
No one knows exactly how this particular mainland iguana made it’s way to the islands, but chances are it didn’t float. With flights and ships arriving from the mainland on a daily basis, it’s far more likely that the iguana was either a stowaway or someone intentionally brought it along to keep as a pet and it escaped or was released.
One wayward iguana may not seem like a big deal, but in the Galapagos it has the potential to be devastating. Because the plants and animals of the Galapagos evolved in isolation, they are highly susceptible to new diseases carried from the mainland and to completion from and predation by new arrivals.
Philornis downsi for example, is a species of invasive fly, the larvae of which feeds upon the nestlings of certain Galapagos bird species. The endemic mangrove finch, which is down to only about 100 birds in the wild, has been particularly hard it and could become extinct because of Philornis in the near future. Invasive species also often prey upon or outcompete native species for food and other resources.
The fact that the mainland iguana was identified and captured is a good sign. Now more than ever local people in the Galapagos are aware of the dangers posed by invasive species. You can do your part when visiting the islands by making sure that you aren’t carrying any accidental stowaways with you. While it’s unlikely that an iguana is going to crawl into your suitcase, it’s not at all uncommon for seeds and other potentially harmful organic materials to hop a ride on shoelaces and other articles of clothing.