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Guam Invasive Species
Invasive species not only threaten Guam’s biodiversity but also impose significant economic costs. These include direct damages to infrastructure, agriculture and tourism, as well as the cost of control programmes. Below is a summary of estimated impacts based on available data.
| Category | Impact Description | Estimated Cost | Sources |
|---|---|---|---|
| Electrical Outages | Brown tree snakes climb utility poles and cause short circuits. Outages disrupt businesses, schools and homes. | $1–4 million/year in repairs and lost productivity | Government reports, economic analysis |
| Agricultural Damage | Feral pigs root and trample crops; deer and buffalo consume seedlings, fruits and vegetables. They also damage fences and irrigation lines. | Millions of dollars in lost yields; exact figures vary by season | USDA–APHIS reports |
| Forest & Cultural Resources | Loss of cycads, pandanus and coconut palms due to scale insects and beetles reduces cultural resources and ecosystem services. | 25% of coconut trees damaged; 90% of cycads killed (monetary value difficult to quantify) | Landgrant Impacts, ScienceDaily |
| Public Health & Tourism | Little fire ants and brown tree snakes inflict painful stings and bites, causing medical costs and deterring outdoor recreation. Anaphylactic reactions can be life‑threatening. | Costs include medical treatment and reduced tourism revenue; no comprehensive estimates available | StopLFA facts |
| Management & Control | Expenditures on traps, baits, personnel and research for invasive species control programmes. | Over $7 million/year for brown tree snake control alone (federal and local combined) | Programme budgets |
Note: Some costs are difficult to monetise, such as the loss of culturally important species and ecosystem services. However, the estimate of $5 million in total invasive species losses used by Guam’s government likely understates the true impact.
Beyond the direct expenses listed above, invasive species impose indirect costs on health, quality of life and the environment. Brown tree snake bites require medical treatment and sometimes result in hospitalisation. Feral pigs contaminate water sources with pathogens, posing risks to human and livestock health. The loss of birds, which pollinate plants and disperse seeds, reduces crop pollination and forest regeneration.
There is also the opportunity cost of resources diverted from other needs like education and infrastructure. Investing in prevention and rapid response not only protects Guam’s natural heritage but also saves money by avoiding these hidden costs.