Green iguanas gone wild in Puerto Rico
I am going to dedicate my first formal post to a topic that I am really interested in: Invasive Species. Specifically, I’ll tell you a little bit about invasive green iguanas in Puerto Rico.
At first, cherished as pets by many, now green iguanas (Iguana iguana) are seen as a green plague in some of the places they were introduced and became invasive. Green iguanas are native to Central and South America, and some of the Lesser Antilles. After the 1970s, humans introduced iguanas to many places where they are not native through the pet trade. In some of these places, such as Florida, Grand Cayman and Fiji, iguanas have become invasive and cause negative economical and ecological impacts. Puerto Rico is no exception, and green iguanas have been expanding their geographic distribution aggressively for the past decade, quickly becoming a nuisance for some. But, are they causing negative impacts that merit the management of the populations?
Let’s try to address this question first by evaluating the negative ecological impacts that green iguanas are causing. They commonly inhabit coastal and riverine areas, and are usually associated with mangrove forests in the coast. Here, iguanas consume the apices (the growing part of the leave shoots) of the mangroves, impeding growth and sometimes increasing mortality rates of these trees. Mangrove forests are nesting areas for many species of birds, and also many marine species spend one or more developmental stages thriving between the roots. The impact of green iguanas, combined with disturbances such as hurricanes and habitat destruction pose a threat for the conservation of mangrove forests and the species that depend upon them. On the other hand, studies on the diet of green iguanas in Puerto Rico have suggested that these reptiles may be acting as dispersers of weeds, which could bring more negative impacts to the ecosystems.
They can also cause negative economic impacts. Here in Puerto Rico, female iguanas dig tunnels and nest along roads constructed in areas with loose soils, especially in the coast, causing the deterioration of these structures. This results in augmented coasts of maintenance and reparations. For some time, green iguanas often halted the air traffic of the LMM International Airport in Carolina, due to incursions to the runways. This of course resulted in economic losses until the administration invested money for the construction of special fences in order to deter iguanas from entering the runways. Agriculture has also been affected by the invasion of these reptiles, especially in the southeast of the island because they eat and damage crops. In addition, they have developed some taste for ornamental gardens, and have been known to inflict damages that surpass the million dollars in losses.
Not everything is negative with the introduction of green iguanas. Often, tourists are attracted to these exotic reptiles. Moreover, many tourist shops sell souvenirs inspired by these reptiles, even though they are not native, generating economic gains. Tours to the natural areas of Puerto Rico have also benefited from the invasion of green iguanas because tourists enjoy watching them in their “natural” habitat. Another thing to consider is that some people in the island don’t see iguanas as negative and enjoy and support having them around. Given the extension of their geographic distribution and population sizes, green iguanas are here to stay, so the only management option is population control. This of course means that the agencies in charge (Department of Natural and Environmental Resources) would have to spend large amounts of money and resources to control green iguanas. Does the costs of management outweigh the negative impacts of green iguanas in Puerto Rico? We cannot answer this question due to the lack of studies at the moment, which calls for the development of new studies in order to make an inform decision.
Meanwhile, something that can alleviate the negative impacts that iguanas are causing is the development of an industry to export meat as a delicacy to the US, and possibly to countries in Central America. At this moment, the perception of green iguanas as food in Puerto Rico is not very popular, but in their native range and other parts, their meat and eggs are considered a delicacy. Hunting iguanas for food has diminished and sometimes decimated populations in their native range, so we could expect the same to occur in Puerto Rico. This alone, may be an effective way for controlling the populations in which the government agencies do not have to spend money and resources, but at the same time generates income for the meat export industry.