Nile Monitor Lizards

Many exotic arrivals to Florida do not appear in the public conscientiousness. For example, the mainstream public is typically unaware that the number of non-native lizard species breeding in Florida now exceeds the number of native species, with over three times as many exotic species as native in south Florida (Hardin 2007), and many of the exotic lizard species can eat various life stages of other lizards (Meshaka et al. 2004). Nonetheless, problems with several large lizard species recently have received public/media attention, a factor sometimes serving to catalyze action. Notable among these are problems from a very large (up to 2.3 m), visible lizard, the Nile monitor (Varanus niloticus), which over the last 15+ years has become firmly established in the Cape Coral area (Enge et al. 2004), and also now appears established in the Homestead area (USDA/Wildlife Services unpublished data). Nile monitors have been commonly sold in the U.S. pet trade (Bayless 1991; Faust 2001), although the size and disposition of the adults makes them ill-suited to captivity (Bennett 1995). This species may be on the cusp of no-return in terms of its potential for eradication from Florida. Its range around Cape Coral is expanding into neighboring wildlands, and it also has become established on nearby Pine Island, and possibly Sanibel Island as well, where it would be a threat to endangered sea turtles and shore birds (Enge et al. 2004; Campbell

The Nile monitor can rapidly outgrow many, if not most, potential predators (Meshaka

2006), and this large-bodied carnivore is capable of eating a wide variety of vertebrate prey, potentially impacting a number of threatened and endangered species in the process (Meshaka 2006). For example, the burrowing owl (Athene cunicularia), a Florida Species of Concern, has already been observed as a prey item (Hardin 2007). This is a prolific species capable of reaching high densities (Western 1974). Based on its native range, this lizard could expand its range and pose severe threats to native fauna throughout Florida, and possibly beyond (Enge et al. 2004).

An intense and prompt eradication effort might still eliminate the Nile monitor from Florida. Accumulation of useful information for the management of the species has begun (Campbell 2005). However, this would be a novel species to subject to control activities. Considerable development of methods and technologies would be needed for the implementation of a practical, broad-based control or eradication program. Basic information on diet, baits, and trapping technology exists (Campbell 2005). Considerable testing and refinement of additional baits, attractants, and capture methods applicable to large-scale removal are needed. Building on the successful development of acetaminophen as a toxicant for brown tree snakes (Savarie et al. 2001), trials have been initiated and shown promise for this compound to also be effective for Nile monitors (R. Mauldin and P. Savarie, National Wildlife Research Center unpublished data). Despite a reasonably high profile and media attention, funding has not yet materialized for general development of the needed control technologies, nor for initiating a general control or eradication effort. Without prompt action, the likelihood for successful eradication diminishes. It remains to be seen if denial of "de Nile monitor" will take place in time.

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