The Nile monitor, a predatory lizard native to sub-Saharan Africa, has been an invasive species in southern Florida since its first reporting in 1990. They are suspected to have entered the area through the pet trade industry and currently pose a danger to marine turtles, wading birds, gopher tortoises, and burrowing owls.
A study published in Southeastern Naturalist documented a reproducing population in the Cape Coral area and warned that the lizards could threaten sea turtles, waterbirds, and burrowing owls as they spread into nearby sensitive habitats. These lizards are able to survive in canals, marshes, and coastal environments because of the presence of water and food sources. This illustrates the effects of introducing alien species into the environment in the long run.
How a pet-trade introduction became established
Varanus niloticus is otherwise known as the Nile monitor. It is an extremely powerful and semi-aquatic reptile that has the capacity to grow up to seven feet in length. Monitor inhabits various environments and preys on fish, insects, amphibians, birds, eggs, and other reptiles. How it was introduced remains a mystery, although it could have been due to escape or release from being someone’s pet. The first recorded instances of sightings and captures of Nile monitors in Cape Coral occurred in the 2000s.
Deep Dive
How did Nile monitors become established in Florida?
Which Florida wildlife could be at risk from Nile monitors?
Why is it difficult to remove Nile monitors from Florida?
Nile monitors can swim, burrow, and eat a wide range of prey, which helps them adapt to both natural and urban habitats. Research published in Royal Society Open Science identified three distinct groups in Florida: the Cape Coral group, the West Palm Beach group, and the Homestead Air Reserve Base group. As per the genetic analyses, the populations have been introduced independently, while the origin of their sampled ancestors could be linked to the coastal areas of West Africa.
Why native wildlife is at risk
{{/usCountry}}Nile monitors can swim, burrow, and eat a wide range of prey, which helps them adapt to both natural and urban habitats. Research published in Royal Society Open Science identified three distinct groups in Florida: the Cape Coral group, the West Palm Beach group, and the Homestead Air Reserve Base group. As per the genetic analyses, the populations have been introduced independently, while the origin of their sampled ancestors could be linked to the coastal areas of West Africa.
Why native wildlife is at risk
{{/usCountry}}They are generalist eaters since they consume a variety of prey items instead of a specific type of animal. This makes ground-nesting animals vulnerable because the lizards can hunt eggs, hatchlings, and other available prey in Florida. Cape Coral is significant since it contains the biggest known population of burrowing owls in Florida. Burrowing owls are small birds that use underground burrows for nesting and shelter. Sea turtles and wading birds are yet another group of species considered at risk. Sea turtle eggs and juveniles, as well as ground-nesting birds and their eggs, can be vulnerable to large lizards.
However, the fact that Nile monitors can eat these animals is not conclusive proof that they are driving population declines in Florida. The impact of Nile monitors varies by species and location and needs further study. A study in the Journal of Heredity also brought into consideration the possible impacts of the monitors on endangered species, such as burrowing owls, gopher tortoises, and American crocodiles. Their combination of mobility, ability to reproduce, and variety in diet makes them a threat even if the true ecological impacts cannot be quantified.
Containing the spread remains a challenge
Eliminating the invasive reptile species that have settled in a certain region is quite challenging since the species is able to survive in burrows, canals, and places that are hard to reach. Since the species can move in freshwater as well as salty water, it becomes increasingly difficult to trap the reptiles since they might at one point settle in other environments that are close. There are certain regions in North America where this reptile can survive, though it is not known which ones.
Since 2021, Florida has put the Nile monitor on the list of prohibited species. Regulations prohibiting the entry of such species into the state have become stricter. People are advised to report any sightings and to take action so that the species can be removed from the location. The City of Cape Coral has implemented an action plan to trap the species so as to minimize the threat to native species.