2IGUANA • VOLUME 14, NUMBER 3 • SEPTEMBER 2007
An adult male Green Iguana (Iguana iguana) basking on a dock in Hollywood, Broward County, Florida.
KRYSKO, ET AL
IGUANA • VOLUME 14, NUMBER 3 • SEPTEMBER 2007 3
The Green Iguana, Iguana iguana (Linnaeus 1758), was first
reported in the 1960s in Florida as occurring, but not
breeding, on the southeastern coast from Hialeah, Coral Gables,
and Key Biscayne in Miami-Dade County. Over the next few
decades, many residents enjoyed watching these large exotic
lizards, allowing them to roam unmolested on their properties,
and at times even feeding them. By the mid-1990s, however,
many residents’ attitudes changed as iguana populations
exploded, often becoming a nuisance to humans and having a
negative impact on the environment. Although many authors
have documented the occurrence of I. iguana populations in
Florida, none fully illustrate this species’ expansive geographic
distribution or remark on its potential effects. Herein, we doc-
ument the current geographic distribution using voucher spec-
imens and field observations, potential ecological impacts, and
nuisance value of this non-native species in Florida.
Materials and Methods
Locality records of Iguana iguana were obtained from the liter-
ature and from systematic collections throughout the United
States. Fieldwork was conducted from May 1992 through
December 2006; I. iguana were collected by hand, noosing, and
shooting small tapered corks from a blowgun (for neonates
only). In addition, photographs were taken and used as vouch-
ers. Specimens were deposited in East Tennessee State University
(ETMNH), Indiana State University Vertebrate Collection
(ISUVC), Florida Museum of Natural History, University of
Florida (UF), United States National Museum (USNM), and
Yale Peabody Museum (YPM). All records with locality data
were plotted using ArcView v. 3.2 (ESRI).
Distribution and History of Introductions
The native range of Iguana iguana extends from southern
Mexico to central Brazil and Bolivia (Lazell 1973, Savage 2002),
Distribution, Natural History,
and Impacts of the Introduced
Green Iguana (Iguana iguana) in Florida
Kenneth L. Krysko1, Kevin M. Enge2, Ellen M. Donlan3, Jason C. Seitz4, and Elizabeth A. Golden5
1Florida Museum of Natural History, Division of Herpetology, University of Florida, Dickinson Hall,
Museum Road, Gainesville, Florida 32611-7800, USA (firstname.lastname@example.org)
2Florida Fish and Wildlife Conservation Commission, Joe Budd Wildlife Field Office,
5300 High Bridge Road, Quincy, Florida 32351, USA (email@example.com)
3Vegetation Management, South Florida Water Management District, 3301 Gun Club Road, West Palm Beach, Florida 33406, USA (firstname.lastname@example.org)
4Creative Environmental Solutions, Inc., 1425 NW 6th Street, Gainesville, Florida 32601, USA (email@example.com)
5Bill Baggs Cape Florida State Park, 1200 South Crandon Boulevard, Key Biscayne, Florida 33149, USA (firstname.lastname@example.org)
Abstract.—In this article, we document the geographic distribution, reproduction, potential ecological impacts, and nuisance value of
the non-native Green Iguana (Iguana iguana) in Florida. We further provide management recommendations for control of this species
in Florida. Locality records of I. iguana were obtained via the literature and both photographic and specimen vouchers, and also from
the field, where specimens were collected and observations made from May 1992 through December 2006. We compiled 3,169 records
of I. iguana in Florida. Iguana iguana was first reported (but not breeding) in Florida in 1966 from Miami-Dade County; however, it is
now reproducing and established in much of southern Florida, including many Florida Keys. We observed I. iguana mating as early as
December and as late as April. Ovipositioning usually takes place in sandy areas. Females were found to have vitellogenic follicles in
November, December, and February; carried oviducal eggs between February and April; and we found a single clutch of 41 eggs that
was oviposited in April. Neonates were observed from May through August. Iguana iguana feed on a variety of vegetation, as well as
insects, tree snails, and possibly small mammals. This species causes considerable damage to landscape vegetation and often is consid-
ered a nuisance by land managers and property owners. Burrowing by Green Iguanas causes erosion and undermines sidewalks, foun-
dations, seawalls, berms, and canal banks. They also force vehicular traffic to brake; deposit unsightly and unhygienic defecations on
moored boats, seawalls, docks, porches, decks, pool platforms, and inside swimming pools; potentially act as seed dispersers for invasive
plant species; and may transmit Salmonella to humans. A number of steps can be taken by Florida landowners to help control I. iguana
in the state: First, vegetation selected for landscaping should lack the showy flowers and colorful fruits that are eaten preferentially by
iguanas. Second, trapping and removing live lizards can be undertaken using live traps (e.g., Havahart, Tomahawk), snare traps, and
nooses. Third, artificial nesting sites can be easily constructed and monitored during the reproductive season so that iguana eggs can be
removed and destroyed. Finally, before purchasing pet iguanas, prospective owners should be educated on the life history details (e.g.,
large adult size, potential to inflict painful wounds, etc.) and complex husbandry requirements of this lizard, and be made aware that
releasing this or any other non-native animal into the wild is illegal in Florida.
GREEN IGUNA IN FLORIDA
4IGUANA • VOLUME 14, NUMBER 3 • SEPTEMBER 2007 KRYSKO, ET AL
including the Caribbean islands of Cozumel (J.C. Seitz, pers.
obs.), San Andrés and Providencia, Roatán, Utila, Swan Island,
Cayo Icacos, Curaçao, St. Vincent and the Grenadines,
Grenada, Îles des Saintes, Montserrat, Saba, St. Lucia, and
Trinidad and Tobago (Bakhuis 1982, Murphy 1997, Schwartz
and Henderson 1991). Green Iguanas have been introduced in
Grand Cayman (Seidel and Franz 1994), Guadeloupe (Lever
2003), St. Martin/St. Maarten (Powell et al. 2005), Puerto Rico
(Thomas 1999), Hawaii (McKeown 1996), the southern Rio
Grande Valley in Texas (Meshaka et al. 2004a, Bartlett and
Bartlett 2006), and Florida (Wilson and Porras 1983). The ori-
gin of the U.S. Virgin Islands population has been disputed for
some time (Lazell 1973), with some authors contending that
iguanas were introduced by man (see Thomas 1999).
We compiled 3,169 records of I. iguana from southern
Florida; 1,088 of these represent preserved specimens and pho-
tographic vouchers collected between 1965 and 2006
(Appendix) and 2,081 represent field observations. The species
is widely established along the Atlantic Coast in Broward,
Martin, Miami-Dade, Monroe, and Palm Beach counties, and
along the Gulf Coast in Collier and Lee counties. Although I.
iguana has been found farther north in Alachua, Highlands,
Hillsborough, Indian River, and St. Lucie counties, no voucher
specimens exist for these scattered localities (except Alachua, UF
122514) and these individuals are unlikely to represent estab-
lished populations due to low winter temperatures. 1
King and Krakauer (1966) recorded the first Florida
voucher specimen (UF 22910, Table 1) collected in 1965 from
Coral Gables, and subsequently reported I. iguana as an estab-
lished, but non-breeding species from four separate areas in
Miami-Dade County: East 7th Avenue and West 27th Street in
Hialeah, Caballero Boulevard and Hardee Road in Coral
Gables, southwest corner of Miami International Airport, and
Key Biscayne. More than 300 individuals were released between
May and September 1964 at the Hialeah site (King and
Krakauer 1966). Wilson and Porras (1983) reported I. iguana
from the Miami Seaquarium on Virginia Key, and Butterfield et
al. (1997) speculated that this species had probably been breed-
ing in Miami since around 1980. Although I. iguana is occasion-
ally observed in Everglades National Park (e.g., nine sightings in
1995–2004), a population has apparently not become estab-
lished, possibly because of the presence of potential predators
and competitors, and the lack of suitable nesting sites (Meshaka
et al. 2000, 2004a, 2004b). Iguana iguana was first documented
from Broward County in Davie (Townsend et al. 2002), and
Palm Beach County in Loxahatchee National Wildlife Refuge
and Palm Beach Gardens (Krysko et al. 2005). We pho-
tographed this species in 2006 in Port Mayaca, Martin County.
Bartlett (1980) first observed I. iguana in southwestern
Florida in Collier County, but did not identify a specific local-
ity. Krysko et al. (2005) documented the first voucher specimens
from Collier County (collected as early as 1998) in Golden
Gate. Iguana iguana has been established for at least a decade on
Marco Island (N. Richie, pers. comm.), and in 2005 this species
was observed along the mangrove fringe between Goodland and
Goodland Bay (K. Laakkonen, pers. comm.), the Florida
Panther National Wildlife Refuge (D. Giardina, pers. comm.),
Copeland (within Fakahatchee Strand Preserve State Park), and
in Naples. In Lee County, I. iguana has been reported from
Cape Coral (Bartlett and Bartlett 1999, Krysko et al. 2005), and
Bonita Springs between Williams Road and the Imperial River
since about 2000 (Spinner 2005).
Duquesnel (1998) first observed I. iguana in the upper
Florida Keys at John Pennekamp Coral Reef State Park, Key
Largo. Krysko et al. (2005) documented this species in the lower
Florida Keys from (east to west) Little Torch and Sugarloaf keys,
and Stock Island. More recently, these findings have been aug-
mented with voucher specimens from Key Largo, Windley Key,
Big Pine Key, Vaca Key, and Key West; and with observations
only from Plantation, Duck, Little Crawl, Bahia Honda, Middle
Torch, Summerland, Cudjoe, Lower Sugarloaf, Big Coppitt, and
Boca Chica keys.
Food Habits and Predators
Neonate and juvenile Iguana iguana feed on vegetation (i.e., new
shoots, leaves, blossoms, and fruits) and insects such as grasshop-
pers (Hirth 1963). In addition to these items, adults have been
reported to feed on bird eggs (Lazell 1973) and carrion (Loftin
and Tyson 1965). In Florida, neonates and juveniles feed on veg-
etation, insects, and tree snails (Townsend et al. 2005), whereas
adults are primarily herbivorous, but may take additional items
as well. A juvenile I. iguana appeared to be feeding on Firebush
(Hamelia patens) fruits in a Naples garden (J. Schmid, pers.
comm.). Fecal contents of a Homestead, Florida individual
included flowers, leaves, and fruits from non-native Jasmine
(Jasminum sp.) and Washington Fan Palms (Washingtonia
robusta; Meshaka et al. 2004b). At Bill Baggs Cape Florida State
Park (BBCF) on the southern tip of Key Biscayne, we have
observed I. iguana feeding on Nicker Bean (Caesalpinia bonduc),
Records (N = 3,169) of Green Iguanas (Iguana iguana) in southern
Florida. Open circles indicate preserved specimens and photographic
vouchers (N = 1,088) collected between 1965 and 2006, circles with
central dots indicate observations (N = 2,081). A dot may represent
more than one record.
and we have collected specimens that had eaten tree snails
(Drymaeus multilineatus; see Townsend et al. 2005) and an adult
(UF 137405) found dead-on-road (DOR) with mammal hair
in its mouth. At Crandon Park on Key Biscayne, I. iguana eats
cracked corn supplied to captive waterfowl, and adults removed
from an overbrowsed area defecated rat (Rattus sp.) hair (G.
Ward, pers. comm.). Two Green Iguanas were observed feeding
on a Spanish Stopper (Eugenia foetida) just before basking on a
Strangler Fig (Ficus aurea; J.G. Duquesnel, pers. comm.). 2,3
In its native range, I. iguana is preyed upon by a variety of
reptilian, avian, and mammalian species. In Venezuela, juveniles
that had emerged by the thousands over a 14-day period were
preyed upon by three crocodilian, two snake, three teiid lizard,
nine accipiter, four falcon, one owl, three heron, three cuckoo,
two passerine, and six mammalian species, including domestic
dog (Canis familiaris) and cat (Felis domesticus; Antonio Rivas et
al. 1998). Some of the predators identified in its native range
also occur in southern Florida: Boa Constrictor (Boa constrictor),
Spectacled Caiman (Caiman crocodilus), American Crocodile
(Crocodylus acutus), Giant Ameiva (Ameiva ameiva), Barn Owl
(Tyto alba), Broad-winged Hawk (Buteo platypterus), Swallow-
tailed Kite (Elanoides forficatus), White-tailed Kite (Elanus leu-
curus), Osprey (Pandion haliaetus), American Kestrel (Falco
sparverius), Crested Caracara (Caracara cheriway), Great Egret
(Ardea alba), and Smooth-billed Ani (Crotophaga ani; Antonio
Rivas et al. 1998, Greene et al. 1978, Swanson 1950, Wunderle
1981). Cats, Caracaras, and Kestrels are among the most com-
mon predators in Venezuela (Antonio Rivas et al. 1998).
Juvenile Green Iguanas in Florida are eaten by the Florida
Burrowing Owl (Athene cunicularia floridana), Yellow-crowned
Night-heron (Nyctanassa violacea), Yellow Rat Snake (Elaphe
obsoleta), and domestic dog (Engeman et al. 2005b, McKie et
al. 2005, Meshaka et al. 2004b). Potential predators of iguana
eggs are the Raccoon (Procyon lotor), Spotted Skunk (Spilogale
putorius), Fish Crow (Corvus ossifragus), Black (Coragyps atratus)
and Turkey (Cathartes aura) Vultures, feral pig (Sus scrofa), and
domestic dog (Hirth 1963, Sexton 1975).
Eggs and young Green Iguanas possibly are eaten by a vari-
ety of native wildlife species in Florida, and they might provide
an important source of food, particularly in areas with dense
iguana populations and few remaining native prey species.
Neonate I. iguana are frequently found on the ground, in shrubs,
or low in trees (Henderson 1974, Hirth 1963, Swanson 1950),
exposing them to different predators than adults, which are usu-
ally high in trees. In Florida, once I. iguana reaches about 60 cm
TL, it has few adversaries except humans, possibly domestic dogs,
American Alligators (Alligator mississippiensis; see Kern 2004), and
American Crocodiles, and is frequently found in open areas.
Green Iguanas of all sizes are collected by humans for the pet
trade, nuisance control, and human consumption. 4,5
In its native range, adult male Green Iguanas have larger home
ranges (up to 9,000 m2) than females and juveniles (Rand et al.
1989). In Costa Rica, mating occurs in October–November
(possibly December in Tortuguero) during the dry season
(Hirth 1963). Females are known to travel up to several kilo-
meters to reach suitable nesting sites, where they nest either
alone or communally (Alvarez del Toro 1960, Rand 1968,
Rand and Dugan 1983). Nesting sites are usually in sandy open
areas, such as riverbanks, islands, or beaches (Burghardt et al.
1977, Campos 2004, Haller and Rodrigues 2005, Hirth 1963),
and females exhibit nesting site fidelity (Bock et al. 1985). In
Panama, I. iguana sometimes shares nesting sites with American
Crocodiles, whose nest defense behavior may disrupt iguana
nesting activities (Bock and Rand 1989); similarly in
Honduras, iguanas eggs have been uncovered in a Spectacled
Caiman nest (Carr 1953). Female I. iguana typically dig an egg
chamber 10–120 cm deep and 100–463 cm long (Haller and
Rodrigues 2005, Rand 1968, Rand and Dugan 1980), but
complex nests shared by multiple females may have a system of
interconnecting tunnels up to 24 m long (Rand and Dugan
1983). Female I. iguana plug the nest tunnel, which is 10–15
cm wide and 7–10 cm high, with substrate using the snout
(Rand 1968). Ovipositioning of 10–71 eggs (Campos 2004,
Fitch 1985, Haller and Rodrigues 2005, Hirth 1963, Rand
1968, Swanson 1950) occurs in late afternoon (rarely in the
morning) between early February and April in Mexico and
Central America (Alvarado et al. 1995, Alvarez del Toro 1960,
Bock and Rand 1989, Hirth 1963, Swanson 1950). Nesting
IGUANA • VOLUME 14, NUMBER 3 • SEPTEMBER 2007 5GREEN IGUNA IN FLORIDA
A juvenile Green Iguana (Iguana iguana) on a non-native Golden
Dewdrop (Duranta erecta) in Naples, Collier County, Florida (photo-
graphic voucher UF 146274). This iguana appeared to be foraging on
fruit from an adjacent Firebush (Hamelia patens).
JEFFREY R. SCHMID
Two Green Iguanas (Iguana iguana) on a Strangler Fig (Ficus aurea) on
Key Largo, Monroe County, Florida (photographic voucher UF
149986). These iguanas were observed feeding on adjacent Spanish
Stopper (Eugenia foetida).
JAMES G. DUQUESNEL
may take place from December to February in the Lesser
Antilles (Lazell 1973), from late January to March in Colombia
(Muñoz et al. 2003), and September to December in Brazil
(Campos 2004, Haller and Rodrigues 2005). Incubation of
eggs takes approximately three months (Alvarez del Toro 1960;
Swanson 1950). In southern Florida, we observed Green
Iguana mating behavior, including male combat, as early as
December and lasting through April. Ovipositioning usually
takes place in sandy areas, but one known female nested in a
mulch pile on Key Largo (J. Duquesnel, pers. comm.). We col-
lected: (1) Four females with vitellogenic follicles (mean = 30.2
± 4.5 mm, 20–42 mm) from November, December, and
February; (2) 22 females with oviducal eggs (mean = 35.5 ± 2.9
mm, 12–62 mm) between February and April; and (3) A sin-
gle clutch of 41 eggs oviposited in April. Neonates are observed
from May to August in both the southern peninsula and
Nuisance Problems in Florida
From the 1960s through the 1980s, many residents in Miami
enjoyed watching the large exotic Iguana iguana, allowing them
to roam unmolested on their properties and at times even feed-
ing them. Prior to Hurricane Andrew in 1992, I. iguana was not
generally considered a nuisance species, but populations
exploded in the 1990s in many areas of southeastern Florida. In
1992, a large reptile dealer in Hollywood, Broward County, pur-
chased few I. iguana that were captured locally (R. Van
Nostrand, pers. comm.); now this species can be captured by the
hundreds in this county and in adjacent Palm Beach County to
the north. According to newspaper articles since 2003, I. iguana
populations have increased markedly to nuisance levels in
Pompano Beach, Pembroke Pines, Dania Beach, Plantation,
Davie, Delray Beach, and Boca Raton. In the past few years, I.
iguana began appearing in large numbers in the Keys, sometimes
crossing roads and forcing traffic to brake along U.S. 1, which
prompted the Florida Keys Invasive Species Task Force to solicit
advice from the Florida Fish and Wildlife Conservation
Commission (FWC) and Florida Museum of Natural History
(FLMNH) on how to control or eradicate these populations. 6,7
On Key Biscayne, the post-Hurricane Andrew I. iguana
population explosion was possibly due to opening up of the
canopy, subsequent replanting of non-native landscape vegeta-
tion favored as food by iguanas (see Meshaka et al. 2004a), and
creation of suitable nesting areas. This aggressive replanting of
ornamental vegetation occurred throughout southeastern Florida
after the widespread destruction caused by the hurricane. Before
the hurricane, Bill Baggs Cape Florida State Park (BBCF) was
extensively vegetated by non-native Australian Pines (Casuarina
equisetifolia), thus iguana food and iguanas were scarce. After
most of the Australian Pines were destroyed by the hurricane,
BBCF park staff eventually began efforts to restore natural habi-
tats and native vegetation. Fallen trees and other hurricane debris
at BBCF and the county-owned Crandon Park to the north on
Key Biscayne were mulched and bulldozed into piles, creating
exposed, well-drained mounds that served as ideal sites for I.
iguana to dig nesting burrows. Iguana iguana became so com-
mon at BBCF that, in 2003 alone, 824 iguanas were removed,
mostly by one of us (EMD; see also Townsend et al. 2003), who
also compiled these records into the park database. Meshaka et
al. (2004a) attempted to illustrate increasing and high popula-
tion densities of I. iguana at BBCF based solely on records main-
tained in the park database from 1 July 1998 through 30 June
2003 (reported therein as 0, 0, 1, 12, 384, respectively); however,
the park database records are incomplete. Although we also
believe that I. iguana has increased there (and other areas) since
the late 1990s, the values reported for 2003 are elevated solely
because of the collecting effort by EMD, who focused on remov-
ing non-native wildlife beginning in 2003 and ending upon leav-
6IGUANA • VOLUME 14, NUMBER 3 • SEPTEMBER 2007 KRYSKO, ET AL
Two adult male Green Iguanas (Iguana iguana) fighting on 24
February 2004 on a dock in Hollywood, Broward County, Florida.
Two Green Iguanas (Iguana iguana) being fed by humans on a dock on
Sugarloaf Key, Monroe County, Florida (photographic voucher UF 131549).
KENNETH L. KRYSKO
Green Iguanas (Iguana iguana) basking on a dock in Hollywood,
Broward County, Florida. Note iguana feces covering the deck.
IGUANA • VOLUME 14, NUMBER 3 • SEPTEMBER 2007 7
ing BBCF in March 2004. If one were to calculate and expand
on the actual numbers of I. iguana removed from BBCF from
1998 through 2006 (0, 0, 0, 9, 57, 824, 265, 189, and 89,
respectively), after the point in which EMD left BBCF, this
would erroneously illustrate a severe population crash.
Iguana iguana can cause considerable damage to residential
and commercial landscape vegetation and is now often consid-
ered a nuisance by land managers and property owners, who
sometimes have to install wire mesh or even electric fences
around herbs, shrubs, and trees to protect them from these vora-
cious lizards. Vulnerable young trees, and older trees with foliage
or flowers particularly attractive to iguanas, can be protected
from climbing lizards by encasing part of their trunks with sheet
metal, as long as other trees are not within leaping distance. For
many years, staff at Fairchild Tropical Botanic Garden in Miami
tolerated I. iguana and prohibited their removal, until escalating
populations started eating prized orchids (Orchidaceae) and the
historic Hibiscus (Hibiscus spp.) garden was overgrazed to the
ground and had to be relocated to a safer location. Other favored
food plants include Impatiens (Impatiens spp.), Rose (Rosa spp.),
Nasturtium (Tropaeolum majus), Caladium (Caladium spp.),
Purple Heart (Tradescantia [Setcreasea] pallida), Bougainvillea
(Bougainvillea spp.), and Hong Kong Orchid Tree (Bauhinia
blakeana; see Kern 2004, Johnson 2006). Iguana iguana will eat
most fruits (except citrus) and flowers, tender new growth, and
almost anything planted in a vegetable garden (Kern 2004). In
the 2000s, I. iguana ate most of the recently planted butterfly
garden at the Key Deer National Wildlife Refuge on Big Pine
Key (C. Bergh, pers. comm.). 8
Iguana iguana also is considered a nuisance by homeown-
ers in part due to unsightly and unhygienic defecations on
docks, moored boats, seawalls, porches, decks, pool platforms
and inside swimming pools. Iguana iguana can transmit the
infectious bacterium Salmonella to humans through their feces,
which conceivably could occur if iguanas defecate in swimming
pools or on food while people are eating outside. Some I. iguana
dig burrows that are used as refugia, which can be accompanied
by erosion that undermines sidewalks, foundations, seawalls,
berms, and canal banks (Kern 2004, Johnson 2006). Although
I. iguana usually uses burrows only as temporary refugia when
away from water, over 100 iguana burrows (up to 4.5 m long)
were observed in a seasonally flooded borrow pit in Venezuela,
which were used as nocturnal refugia despite the presence of
numerous trees (Rodda and Burghardt 1985). In treeless habi-
tats in Florida, such as cleared canal banks and vacant lots, nor-
mally arboreal lizards seek shelter in burrows, culverts, drainage
pipes, and rock or debris piles.
Large I. iguana basking on airport runways could pose a
hazard to planes. At least five known records document airplanes
colliding with iguanas at the international airport in San Juan,
Puerto Rico, where this species was introduced, and large igua-
nas would have a relative hazard score equivalent to ducks and
pelicans (Engeman et al. 2005a). Iguana iguana also can be
observed basking and grazing on golf course fairways in Florida,
but these lizards generally do not pose a hazard to golfers.
Iguana iguana is responsible for more complaints to the
FWC than any other non-native reptilian species in Florida.
Numbers of complaints continue to increase as iguanas expand
their range into new areas, and additional homeowners experi-
ence the dubious thrill of having the reptilian version of a sheep
devouring their landscape. Although many people enjoy watch-
ing I. iguana as long as they do not damage valued plants or
property, many other people are afraid of these large lizards,
especially visitors or new residents, who are not accustomed to
such large prehistoric-looking animals living in their neighbor-
GREEN IGUNA IN FLORIDA
Residence on Big Pine Key, Monroe County, Florida, with wire mesh
installed around flowering plants to protect against Green Iguanas
KENNETH L. KRYSKO
Adult male Green Iguana (Iguana iguana) above a culvert on a canal
bank along U.S. 27 in Medley, Miami-Dade County, Florida (photo-
graphic voucher UF 150123).
KEVIN M. ENGE
hood. Neighbors who were once friendly to each other have
even become rivals and no longer speak, as some families decide
to feed and protect iguanas while other families want to rid these
lizards from their properties (C.D. May, pers. comm.).
Nonetheless, I. iguana will continue to be a common sight in
neighborhoods because of the tolerance of some residents who
feed them, coupled with a scarcity of predators, abundance of
palatable ornamental vegetation (some vegetation with thorns
may ward off potential predators), sunny nesting sites, and the
presence of canals, lakes, and swimming pools for drinking water
and escape cover. Furthermore, the profusion of man-made
canals serve as dispersal corridors that allow iguanas to colonize
new areas. 9–11
Potential Impacts on Other Species
On Marco Island, Iguana iguana occasionally uses burrows of
the Florida Burrowing Owl (N. Richie, pers. comm.), a “Species
of Special Concern” in Florida. At Crandon Park, I. iguana
sometimes shares the same burrow as another non-native species,
the Black Spiny-tailed Iguana (Ctenosaura similis), but most
Green Iguanas utilize trees, particularly those in and around
ponds and canals. The stomach of a juvenile I. iguana from Key
Biscayne contained 12 tree snails (Drymaeus multilineatus), sug-
gesting that it had selectively eaten them (Townsend et al. 2005).
This snail species is common; however, iguanas could potentially
impact other more rare tree snails (Townsend et al. 2005).
The species composition of the plant community might
eventually be altered in areas with dense populations of I. iguana
due to excessive grazing and defoliation of vegetation, resulting
in death or lack of reproduction. In Mexico, I. iguana helps
maintain forest diversity by consuming and dispersing seeds of
many tree species (Morales-Mávil 1997). Iguana iguana is selec-
tive in its diet, and ingested seeds typically have higher germina-
tion rates than uneaten seeds (Benítez-Malvido et al. 2003). In
Florida, I. iguana may be an important seed disperser of non-
native invasive plant species, carrying seeds from people’s yards
into adjacent natural areas and hindering invasive vegetation
control efforts. Iguana iguana at BBCF feed on Nicker Bean, an
important food plant for larvae of the Endangered Miami Blue
Butterfly (Hemiargus thomasi bethunebakeri).
Population Control in Florida
Iguana iguana is now common in many urban areas of the
southern peninsula and Florida Keys, and may be flourishing in
larger natural areas of coastal Florida. Green Iguanas are
extremely popular in the pet trade and sometimes escape or are
intentionally (and illegally) released by owners when they grow
too large. Many pet enthusiasts are unaware (or unwilling to
accept) that releasing non-native animals, including I. iguana, in
Florida is illegal and potentially detrimental to the environment.
Future illegal introductions of non-native animals can be ame-
liorated by incorporating pet owner education into the invasive
species management process. Prospective iguana owners should
be educated on the life history details (e.g., large size of adults,
potential for inflicting painful wounds, etc.) and the complex
husbandry requirements of this species before a purchase. In an
attempt to facilitate disposal of unwanted exotic pets, the FWC
now allows people to return animals (as long as they do not
8IGUANA • VOLUME 14, NUMBER 3 • SEPTEMBER 2007 KRYSKO, ET AL
Two non-native Green Iguanas (Iguana iguana) and a non-native Red-
eared Slider (Trachemys scripta elegans) on non-native Melaleuca
(Melaleuca quinquenervia) along a canal in Opa-Locka, Miami-Dade
County, Florida (photographic voucher UF 150122). Two discarded
automobile tires and other debris litter the man-made canal bank.
KEVIN M. ENGE
Juvenile Green Iguana (Iguana iguana) on a non-native Silk Floss
(Chorisia speciosa) tree in Lake Worth, Palm Beach County, Florida
(photographic voucher UF 149868).
Adult male Green Iguana (Iguana iguana) at the front door of a resi-
dence in Fort Worth, Palm Beach County, Florida.
IGUANA • VOLUME 14, NUMBER 3 • SEPTEMBER 2007 9GREEN IGUNA IN FLORIDA
profit from the transaction by receiving more money than what
was originally paid) to the pet store where purchased without
requiring a costly license to sell wildlife.
Iguana iguana populations at the northern extent of their
introduced range in Florida, as well as individual escapees far-
ther north, are controlled by cold winter temperatures, except
when thermal refugia or urban heat islands are available. When
temperatures drop below 50 ºF, sluggish iguanas can be easily
plucked from trees or collected after falling from trees, especially
at night or on overcast days when basking does not increase
body temperature quickly. Well-established populations in
southern Florida appear to have exceeded the point of human
control, and many animal control officers and nuisance trappers
no longer respond to iguana complaints. Even if removal of I.
iguana is successful, more lizards will repopulate the site from
adjacent areas or when eggs hatch. Some private trappers charge
upwards of $100 to visit an iguana-infested site, and they usu-
ally will not guarantee success in catching and removing lizards.
However, David Johnson, “The Iguana Trapper,” claims to spe-
cialize in removing I. iguana from overpopulated residences and
subdivisions (Johnson 2006). During the past four years in his
Pelican Harbor neighborhood along the C-15 Canal in south-
ern Palm Beach County, Johnson (2006) has removed 406 igua-
nas, and during one week in April 2006, he caught 54 iguanas
at one residence in Pompano Beach. Some residents have taken
matters into their own hands; because I. iguana is a non-native
species, it is not afforded protection in Florida, and it is legal to
catch, trap, and humanely kill these lizards. However, permits
or permission must be obtained before collecting wildlife,
including non-native species, from a county, state, or national
park and other public land. Once a Green Iguana is captured, it
cannot legally be released again in Florida, limiting the captor to
choose between killing the iguana humanely, keeping it in cap-
tivity, or selling it. Selling iguanas is no longer lucrative due to
the availability of inexpensive farm-raised iguanas from Latin
America; some pet stores sell imported neonate iguanas for less
than $10 each. Wild-caught adult Green Iguanas seldom
become tame, but zoos and other exhibits are sometimes inter-
ested in acquiring large individuals (especially orange-colored
males) for display purposes, and foreign buyers may pay up to
$300 for exceptional specimens (G. Ward, pers. comm.). 12
Trapping methods for I. iguana include the use of live traps
(e.g., Havahart, Tomahawk) baited with fruit, such as bananas
or mangoes, or locking snares that can be set during the daytime
at burrow entrances, at holes under fences, or along seawalls
(Kern 2004), canals, and ponds. Johnson (2006) used a semicir-
cular mesh trap with a snare at each end (D-I-Y trap) and bait
in the center. However, the most common capture method is by
noosing with a long pole, especially while lizards are sleeping at
night or torpid during cold weather. Some commercial I. iguana
catchers use boats to noose lizards from trees at night, sometimes
stretching out nets to catch iguanas jumping from trees to the
water below (G. Ward, pers. comm.). Persistent harassment may
encourage I. iguana to move to the next-door neighbor’s yard;
this can be accomplished by launching pebbles or palm fruits at
them using a slingshot (Kern 2004), spraying them with a hose,
or through the use of loud vocalizations on the part of a person
or a dog combined with quickly approaching the lizard.
Shooting firearms is outlawed in residential areas. 13
Over the past few years, we have established a cooperative
effort with personnel at Crandon Park on Key Biscayne to
reduce their abundant I. iguana population. Despite our efforts
and those of commercial collectors, who have additionally
removed hundreds of iguanas annually, this species is still a com-
mon sight. People have been caught illegally releasing their pet
iguanas at Crandon Park because they thought it was an “iguana
nursery.” “Iguana crossing” signs were once posted on Key
Biscayne to advise motorists of a potential driving hazard. Over
time, heavily harvested I. iguana populations can be expected to
have lower densities, smaller individuals, and smaller clutch sizes
than unharvested populations (Muñoz et al. 2003).
Female Green Iguanas are known to travel up to several
kilometers to nest (see Alvarez del Toro 1960; Rand 1968; Rand
and Dugan 1983), suggesting that females return to the same
suitable nesting sites year after year. Desirable nesting sites can
be heavily used by females. A clearing about 6 x 7 m in size on
a 0.3-ha islet (not normally inhabited by I. iguana) in a
Panamanian lake attracted as many as 150–200 females annu-
ally (Burghardt et al. 1977). In the Florida Keys, where I. iguana
is expanding its range and is a nuisance, limestone is often near
the surface, and nesting sites are usually limited to sandy micro-
habitats along beaches or soil and mulch piles brought in from
the mainland for landscaping. Besides removing I. iguana from
the wild whenever possible, in areas where suitable nesting areas
are limited, we recommend establishing artificial nesting sites
and removing the eggs. Suitable nesting mounds using sand,
soil, or mulch can be placed in key problem areas for the express
purpose of luring female iguanas. Monitoring these sites during
the nesting season might help control the population, but care
must be taken to locate and remove all iguana eggs. An easier
solution than laboriously searching a mound of dirt for eggs
would be to construct a small artificial nest box that would con-
centrate iguana eggs. Werner and Miller (1984) designed a sim-
ple but successful nest box using six concrete blocks 40 x 20 x
10 cm (15 x 8 x 4 in) and two clay tubes 30 cm long x 20 cm
outside diameter (12 x 8 in). The interior of the nest chamber
is 40 cm long, 20 cm wide, and 10 cm high (15 x 8 x 4 in) and
filled with loose dirt. The 60-cm (24 in) long entrance tube,
which has a 15 cm (6 in) interior diameter, is one-third to half
Adult male Green Iguana (Iguana iguana) basking on a fallen tree dur-
ing a cool day at Crandon Park on Key Biscayne, Miami-Dade
County, Florida (photographic voucher UF 150121). Non-native
Senegal Date Palms (Phoenix reclinata) can be seen in the background.
KEVIN M. ENGE
filled with a 7-cm (2.75 in) layer of dirt; iguanas will fill this tube
while excavating the nest chamber, indicating that nesting
females or eggs are present and can be removed. This nest box
is set on the surface of the ground and covered with 3 cm (1 in)
of dirt; and the nest chamber is checked for eggs by removing
one or both of the concrete blocks that form the roof. In an arti-
ficial nesting chamber, Werner and Miller (1984) believed that
substrate composition is relatively unimportant (iguanas have
been observed nesting in different mixtures of soil and sand, and
even in ashes and refuse in garbage dumps), but solid walls and
a roof are essential. These artificial nest sites should be moni-
tored during the nesting season and all eggs or iguanas removed
before refilling the nest chambers with displaced dirt from the
entrance tubes. We recognize that this type of artificial nest box
cannot be moved easily once constructed. Thus, we suggest
using lighter-weight materials such as a similarly sized plastic,
rubber, or fiberglass shell (for the chamber) and PVC tube (for
the entrance), which will allow the nest box to be moved easily
to different sites. Furthermore, these artificial boxes can be used
to remove adult Green Iguanas as well as Spiny-tailed Iguanas
(Ctenosaura spp.), as both species utilize burrows throughout the
We thank A. Nichole Hooper, Anthony T. Reppas, Todd S.
Campbell, Julian C. Lee, Andy P. Borgia, Rick Rego, Steve A.
Johnson, Kurt W. Larson, Esther M. Langan, Larry D. Wilson,
Sean B. Thompson, Debbie T. Townsend, Steve H. Townsend,
Bill Love, F. Wayne King, Chris S. Samuelson, Brooke L. Talley,
Kristen L. Bell, Brian J. Camposano, Lorraine P. Ketzler, David
G. Cook, Thomas M. Cravens, Ronald St. Pierre, George J.
Ward, and Mark A. Flowers for assistance in the field; Stan
Chrzanowski, Jim Duquesnel, Keith Laakkonen, Mike Owen,
Thomas Owen, Carl May, Jeffrey R. Schmid, and Anthony
Flanagan for providing photographs and information; Jim and
Janice Duquesnel, Bill Love, Chris Bergh, Dennis Giardina,
Nancy Richie, Raymond Goushaw, Ray Van Nostrand, Carl
May, Kenyatta K. Nichols, and J.H. Altman for information of
iguana populations in Florida; and Audrey K. Owens for illus-
trating the artificial iguana nest box.
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10 IGUANA • VOLUME 14, NUMBER 3 • SEPTEMBER 2007 KRYSKO, ET AL
An artificial nest box constructed using concrete blocks and clay tubes
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inally half filled with a layer of dirt; the layer of dirt (observable by
looking into the tube from the outside) will exceed the half-full mark
when female iguanas excavate a nest chamber inside the box.
Illustration by Audrey K. Owens.
IGUANA • VOLUME 14, NUMBER 3 • SEPTEMBER 2007 11GREEN IGUNA IN FLORIDA
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Appendix. Voucher specimens of Iguana iguana examined from Florida counties.
Alachua: UF 122514; Broward: UF 123126–27, 134066, 146556, 149568–69,
149979–81, 150124; Collier: UF 141486, 146036, 146067, 146273–74,
149612; Lee: UF 133209–10; Miami-Dade: ETMNH-CC 418–32; ISUVC
3846–47, 3849–53, 3855–92; UF 22910, 131544–47, 131556–60,
131764–66, 132864–83, 133838–41, 134203–10, 134231, 134910,
135083–91, 135093–94, 135294, 135470–71, 135485–89, 135494–500,
135538–63, 135616–22, 135624, 135896, 135907–23, 135925–46, 137405,
140562–65, 140579–82, 140740, 141040–41, 141098, 141101–03,
141109–19, 141220–23, 141225–27, 141230–31, 141233–34, 141236–39,
141248–49, 141487–96, 141498, 141609–17, 141766–68, 141897–99,
141902–03, 141953, 142317, 142333–42, 142344–54, 142551–74,
142591–95, 142625–80, 142722–24, 142731, 142812, 142817–19,
142897–904, 143602, 143605, 143607–08, 143946–48, 144060,
144239–41, 144261–65, 144268–97, 144310, 144312–23, 144343–471,
144575, 145202–14, 145218–333, 145335–57, 149715–32, 149734–810,
149873, 149892–978, 149982, 150002–13, 150121–23; USNM 245339;
YPM 13950–52; Monroe: UF 131549, 133862, 134836, 137214, 141212,
145524, 149864, 149985–86, 150065, 150093; Palm Beach: UF 137086,
137183, 146557–72, 149863, 149868–70, 150079.