Florida's Exotic Wildlife. Species detail.
First year: 1990
Extirpated year:
Established status: Populations
are confirmed breeding and apparently self-sustaining for 10 or
more consecutive years.
Estimated Florida range: 1
county At least 10 years, 6 counties Not reported
breeding
Statewide trend: Unknown
status
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Photograph by Dr. Todd S. Campbell © 2003
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Threats to natives: Large
carnivorous species that can dig up reptile eggs (including those
of crocodilians and sea turtles) and prey upon birds, mammals,
frogs, lizards, snakes, fish, and crabs. Cape Coral has the largest
Florida population of burrowing owls (>1,000 pairs), which might
be impacted by monitors usurping their burrows and preying upon
adults, nestlings, and eggs.
Species Account: The Nile
monitor(Varanus niloticus) is the longest lizard in Africa,
attaining a maximum total length (TL) of 243 cm (7' 11'") (Faust
2001), but the median size for adult males is 155 cm (5' 1") TL and
for adult females is 134 cm (4' 5") TL (de Buffrénil et al. 1994).
The Nile monitor has 6-11 light-colored body bands on a black
background and a bluish black, forked tongue (Faust 2001). It has
the widest range of any lizard species in Africa and is the second
most commonly sold African monitor species in the United States
(Faust 2001), despite the fact that its large adult size and
nervous disposition make it a difficult pet to keep. Nile monitors
have been observed in various parts of Florida, but the only
confirmed breeding population is in Cape Coral, Lee County (Enge et
al. 2004a). From April 2001 through 7 July 2003, 159 sightings or
collected specimens (including hatchlings) of Nile monitors were
made in Cape Coral, and since then, over 50 have been trapped
during an eradication effort by Dr. Todd Campbell (Enge et al.
2004a). Prior to this, a reptile dealer claims to have collected
for resale ca. 50 monitors in Cape Coral (Enge et al. 2004a). Most
monitor observations have been in residential areas in southwestern
Cape Coral and along the spreader canal (Enge et al. 2004a). In
Africa, the species occurs along desert fringes and from grasslands
to rainforests in the vicinity of rivers, swamps, ponds, lakes,
seashores, and human habitations (Faust 2001). It shelters in
crevices or burrows, including those of other animals. The most
suitable habitats in Florida are probably mangrove swamps, edges of
freshwater and saltwater marshes, and banks of rivers, canals, and
lakes. This species could potentially all wetland habitats and
adjacent terrestrial habitats in peninsular Florida, including
residential and agricultural areas containing water (Enge et al.
2004a). In Mali and Chad, females reach sexual maturity at ca. 36
cm (14 in) snout-vent length (SVL) or 24 months of age, and ca. 50%
of mature females reproduce each year (de Buffrénil and
Rimblot-Baly 1999). Large females (>71.5 cm or 28" SVL) oviposit
53-60 eggs (de Buffrénil and Rimblot-Baly 1999) that apparently
take 6-10 months to hatch (Faust 2001). In Africa monitors prey or
scavenge for a variety of arthropods, crabs, crayfishes, mussels,
gastropods, fishes, anurans, lizards, turtles, snakes, young
crocodiles, eggs, birds, and small mammals, including domestic
cats. In Florida, Nile monitors could impact populations of nesting
birds (especially burrowing owls), gopher tortoises, nesting sea
turtles, nesting American crocodiles, and other listed species
(Enge et al. 2004a).
Habitats: Freshwater river or
stream, Estuarine community, Exotic plant community, Low density
suburban development, areas peripheral to core urban areas, and
small towns
| County |
First Year |
Extirpated Year |
Breeding status |
Notes |
| DADE |
1990s |
|
Not reported breeding |
Card Sound Road (P. E. Moler, FFWCC, Gainesville; D. Roudebush,
FFWCC, Marathon; T. Crutchfield, Fort Myers, personal
communications); Matheson Hammock (K. L. Krysko, Fla. Mus. Nat.
Hist., Gainesville, pers. commun.); gravid female captured (R. St.
Pierre, Loxahatchee, personal communication) |
| LEE |
1990 |
|
Multiple sightings and ca. 100 captures or roadkills in Cape
Coral (Enge et al. 2004a) |
| BROWARD |
1994 |
|
Not reported breeding |
Multiple sightings in Coral Springs-Tamarac area (M. Lucas,
Coral Springs, personal communication) |
| ORANGE |
2003 |
|
Not reported breeding |
Lake Price photograph (FLMNH voucher) |
| ALACHUA |
1981 |
|
Not reported breeding |
Capture in Lake Kanapaha (K. Enge, FFWCC, Quincy, personal
observation) |
| DE SOTO |
2003 |
|
Not reported breeding |
Several sightings along the Peace River near Fort Ogden,
Arcadia, and Brownville (C. Clark, Punta Gorda, personal
communication) |
| COLLIER |
2000 |
|
Not reported breeding |
Several sightings along Haldeman Creek, Naples (J. Sietz,
Naples, personal communication) |
References
de Buffrénil, V., and F. Rimblot-Baly. 1999. Female
reproductive output in exploited Nile monitor lizard (Varanus
niloticus L.) populations in Sahelian Africa. Canadian Journal of
Zoology 77:1530-1539.
de Buffrénil, V., C. Chabanet, and J. Castanet.
1994. Données préliminaires sur la taille, la croissance et la
longévité du varan du Nil (Varanus niloticus) dans la région du lac
Tchad. Canadian Journal of Zoology 72:262-273.
Enge, K. M., K. L. Krysko, K. R. Hankins, T. S.
Campbell, and F. W. King. 2004a. Status of the Nile monitor
(Varanus niloticus) in southwestern Florida. Southeastern
Naturalist 3:571-582.
Faust, R. J. 2001. Nile monitors: everything about
history, care, nutrition, handling, and behavior. Barron's
Educational Series, Hauppauge, New York. 95pp.
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