Principal source:
Compiler: National Biological Information Infrastructure (NBII) & IUCN/SSC Invasive Species Specialist Group (ISSG)
Review:
Publication date: 2010-07-20
Recommended citation: Global Invasive Species Database (2024) Species profile: Varanus niloticus. Downloaded from http://iucngisd.org/gisd/speciesname/Varanus+niloticus on 02-11-2024.
Reduction in native biodiversity: The Nile monitor is a large intelligent carnivorous lizard which poses a significant threat to the native species of Florida (Campbell 2005). This large lizard has the potential to disperse into ecologically sensitive areas where it could threaten waterbirds, burrowing owls (Athene cunicularia), sea turtles and other wildlife (Enge et al. 2004).
Disease transmission: It has been known for many years that reptiles including V. niloticus that were imported into the United States were often infested with ticks which may also be pathogenic to livestock (Burridge and Simmons 2003). A tick potentially carried by V. niloticus is the east African tick Amblyomma falsomarmoreum (Burridge and Simmons 2003). However the captured lizards in Cape Coral, Florida (United States) had surprisingly few external or internal injuries or parasites, and nearly all were in very good condition (Campbell 2005).
Monitoring: Field surveys for lizards and their burrows, tracks, and sign were conducted but were ineffective for locating and capturing lizards (Campbell 2005).
Physical control: Nile monitors were successfully live-trapped by Campbell (2005). Workers set Havahart live traps baited with squid along canal banks. The lizards were ethically euthanized and were later dissected to reveal their reproductive cycle, diet, and parasite load and to harvest tissues for later demographic, genetic, and ecotoxicological analyses.Campbell (2005) represents a preliminary analysis of this data. Over 100 Nile monitors were captured and euthanized during this study, ranging in size from hatchlings up to large males nearly 2 meters in length and over 12 kilograms in mass (Campbell 2005).
Chemical control: Maudlin and Savarie (2010) investigated the use of acetaminophen, a lethal oral toxicant for the invasive brown treesnake (Boiga irregularis) on Guam, as a possible toxicant against juveniles of the Burmese python and Nile monitor. In Nile monitors, acetaminophen doses of 10, 20, or 40 mg resulted in 0, 50 and 100% mortality, respectively. Acetaminophen was found to be an effective toxicant against juveniles of the Nile monitor and Burmese python.
Education and Awareness: An emergency response program was established in Florida employing local press releases to motivate the public to report lizard sightings.
Legislative measures: Regulatory rules that consolidated laws pertaining to non-native species became effective on January 1, 2008 in Florida, United States. These rules prohibit the release of non-native species and the keeping of certain species as pets. Under the rules, six exotic reptiles including Python molurus bivittatus, P. reticulatus, P. sebae, Morelia amethistina, Eunectes murinus and the Nile monitor Varanus niloticus were identified as reptiles of concern and a permit is now required to possess these species (Fujisaki et al. 2010). Nile monitors are protected under CITES Appendix II and mandatory regulation of international trade is through permits (Levell 1997, Branch 1998, as cited in Somma 2007).