COS 112-6 - Impact of the invasive green iguana on 20 farms in Puerto Rico

Background/Question/Methods

The common green iguana (Iguana iguana) is considered a widespread invasive species in over two dozen islands and territories in the South Pacific, South Eastern Asia and the Caribbean. Where introduced, this invasive species poses a threat to endemic Iguana species through hybridization and competition. Concerns over this herbivorous lizard’s impact on agricultural production have also been cited, though little work has been done to explore the green iguana’s relationship with people. In this study, we begin to explore the impact of the invasive common green iguana on agricultural communities by conducting 20 semi-structured interviews with Farmers in Puerto Rico. We sought to explore the relationship among farm location, habitat features and crops produced with the level of reported impacts. Interview questions were focused on identifying the spatial occurrence of problems with green iguana (i.e which areas of the island had issues); the habitat features of the farm, the specific crops produced, the perceived levels of negative impact and the mitigation strategies taken to reduce any negative effects.

Results/Conclusions

In total 32 of 54 crop species reported by farmers were negatively affected by the green iguana. We found that green iguanas were absent from 20% of farms, did not consume crops in 10% of the farms and caused negative impacts in 70% of the remaining farms. Farms above 400m in elevation (the green iguana's current elevation threshold) reported an absence of the reptiles. We did not identify a relationship among habitat features and negative impacts. Negative impacts included crop loss and infrastructural damage, which had behavioral, emotional and economic effects on farmers. Specific outcomes of these effects were revenue loss, refurbishing costs, changes in crop selection, management costs and emotional stress. Farmers implemented mitigation measures that needed to be constant to produce any positive effects on crop yield. They used mesh fencing, hunting and domestic animals as attempts to reduce negative effects on crop production. By integrating concepts in ecology with methods in social science we were able to gain an initial foothold into the potential impact of the green iguana as an invasive agricultural pest. Broadly, this work should serve as an example of the utility of multidisciplinary approaches in ecology and specifically invasive species management.