The Green Iguana, Iguana iguana, is a well established, large-bodied, exotic species in Florida (Meshaka et al. 2004a. The Exotic Amphibians and Reptiles of Florida, Krieger Publishing Company, Malabar, Florida. 155 pp.; Meshaka et al. 2004b. Iguana 11:154-161). Limiting factors of populations and causes of Green Iguana mortality in Florida are poorly understood and the only documented predators are the domestic dog (Canus familiaris) (Meshaka et al. 2004a), Yellow-crowned Night-heron (Nyctanassa violacea) (Engeman et al. 2005. Herpetol. Rev. 36:320), Florida Burrowing Owl (Athene cunicularia floridana) (McKie et al. 2005. Florida Field Nat. 33:125-127), and an unidentified species of hawk (HTS pers. obs.). Here, we report the first documented predation of a juvenile Green Iguana by a Raccoon (Procyon lotor) in a southern Florida state park. Additionally, we provide strong evidence of Green Iguana population density and recruitment suppression by Raccoons

Bush, Gary

Crossett, Steven M.

Engeman, Richard M.

Foley, Mark E.

Meshaka, Walter E., Jr.

Smith, Henry T.

English

DigitalCommons@University of Nebraska

University of Nebraska - Lincoln DigitalCommons@University of Nebraska - Lincoln USDA National Wildlife Research Center - Staff Publications U.S. Department of Agriculture: Animal and Plant Health Inspection Service December 2006 Raccoon Predation as a Potential Limiting Factor in the Success of the Green Iguana in Southern Florida Henry T. Smith Florida Department of Environmental Protection, Florida Park Service Walter E. Meshaka Jr. State Museum of Pennsylvania Richard M. Engeman USDA-APHIS-Wildlife Services, s_r100@yahoo.com Steven M. Crossett Hugh Taylor Birch State Park Mark E. Foley Hugh Taylor Birch State Park See next page for additional authors Follow this and additional works at: https://digitalcommons.unl.edu/icwdm_usdanwrc  Part of the Environmental Sciences Commons Smith, Henry T.; Meshaka, Walter E. Jr.; Engeman, Richard M.; Crossett, Steven M.; Foley, Mark E.; and Bush, Gary, "Raccoon Predation as a Potential Limiting Factor in the Success of the Green Iguana in Southern Florida" (2006). USDA National Wildlife Research Center - Staff Publications. 448. https://digitalcommons.unl.edu/icwdm_usdanwrc/448 This Article is brought to you for free and open access by the U.S. Department of Agriculture: Animal and Plant Health Inspection Service at DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in USDA National Wildlife Research Center - Staff Publications by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln. Authors Henry T. Smith, Walter E. Meshaka Jr., Richard M. Engeman, Steven M. Crossett, Mark E. Foley, and Gary Bush This article is available at DigitalCommons@University of Nebraska - Lincoln: https://digitalcommons.unl.edu/icwdm_usdanwrc/448 Raccoon Predation as a Potential Limit-ing Factor in the Success of the Green Iguana in Southern Florida   The Green Iguana, Iguana iguana, is a well es-tablished, large-bodied, exotic species in Flori-da (Meshaka et al. 2004a. The Exotic Amphibians and Reptiles of Florida, Krieger Publishing Compa-ny, Malabar, Florida. 155 pp.; Meshaka et al. 2004b. Iguana 11:154-161). Limiting factors of populations and causes of Green Iguana mortality in Florida are poorly understood and the only documented pred-ators are the domestic dog (Canus familiaris) (Me-shaka et al. 2004a), Yellowcrowned Night-heron (Nyctanassa violacea) (Engeman et al. 2005. Her-petol. Rev. 36:320), Florida Burrowing Owl (Athene cunicularia fl oridana) (McKie et al. 2005. Florida Field Nat. 33:125-127), and an unidentifi ed species of hawk (HTS pers. obs.). Here, we report the fi rst documented predation of a juvenile Green Iguana by a Raccoon (Procyon lotor) in a southern Florida state park. Additionally, we provide strong evidence of Green Iguana population density and recruitment suppression by Raccoons. Hugh Taylor Birch State Park (HTBSP) is a small, urban park located in Broward County, Florida, USA, within the City of Ft. Lauderdale. It consists of 56.7 ha of uplands and 14.2 ha of freshwater and tid-al wetlands for a combined total of 70.9 ha. HTBSP is completely encapsulated by urban infrastructure, and the Intracoastal Waterway (a large bulkheaded canal) truncates the entire western boundary.  At ca. 1130 h on 16 October 2006, a sunny day, temperature ca. 85°F, HTBSP Park Rangers SMC and MEF observed a Raccoon chase a ca. 20 cm SVL Green Iguana out of maritime hammock on to one of the park roads. The iguana cut back across the road surface apparently trying to reach the safety of trees/ woodland cover, and the Raccoon then caught it in its jaws and carried it back into the hammock. SMC estimated the entire sequence of events to cov-er less than 15 seconds. This observation brings the list of known predators of invasive Green Iguana in Florida to fi ve. Likewise, this predation observation provides additional support for our hypothesis that an inverted trophic pyramid dominated by artifi cially high midlevel predator biomass of the Raccoon ex-erted almost complete population suppression on an invasive, large-bodied, lower trophic level reptile for at least six years. In subsequent observation, nearly one month later, a large male Green Iguana basking at 1535 h on 9 November 2006 at HTBSP was fi rst circled by a young Raccoon and then attacked. Its response (Figure 1) and follow-up behavior suggest that even large adults are susceptible to attack by Raccoons, and at least during the day, can be suc-cessfully fended off (Figure 1).  Raccoon population densities in the park have always been artifi cially high as a direct result of un-lawful feeding by humans. Estimates of Raccoons in HTBSP during the 1990s ranged from ca. 75 to 125 animals (Smith and Engeman 2002. Canadian Field- Nat. 116:636-639). The threats of epizootic disease transmission (particularly rabies) to other wildlife, bites to humans, and vehicular traffi c hazards, re-sulted in a control program in November 2000 to reduce these threats. The HTBSP trap and remov-al program documented an absolute minimum den-sity of 238 raccoons/ km2 [ = 169 raccoons/175 acres] (Smith and Engeman 2002. Canadian Field-Nat. 116:636-639), which is the third highest Rac-coon density ever reported in North America, 4-200 times greater than the other reported rural densi-ties of 0.9-55.6 Raccoons/ km2 (Smith and Enge-man 2002. op cit.).  During the years of this extraordinary mid-lev-el predator density, few ground-dwelling reptiles were observed in the park and virtually all mast was stripped from trees annually (HTS pers. obs.). The Green Iguana was fi rst opportunistically ob-served by HTS in the park maritime hammock in 1994 and the date of their initial introduction is un-known; however, the very rare individuals encoun-tered in subsequent years were always large adults and in arboreal situations. During frequent visits from 1994 to 2000 for various projects, no evidence of Green Iguana recruitment was found in HTBSP. Since 2001, and after Raccoon removal, new hatch-lings have been observed annually and as of 2006, the Green Iguana has saturated the park in mixed size-classes in all ground, arboreal, and ruderal habitats (HTS and WEM pers. obs.).  The post-Raccoon removal spike in Green Igua-na presence at HTBSP and the depredation of a ca. 60 cm TL Green Iguana suggest to us the effective-ness of the Raccoon as a potentially severely lim-iting factor of Green Iguana abundance in south-ern Florida. In this connection, we propose that predation of the nest, as well, is a mechanism for suppression of the Green Iguana by the Raccoon. The case for nest predation and its effects on theField NotesJournal of Kansas Herpetology Number 20 (December 2006)  7Figure 1. A male Green Iguana (Iguana iguana) fends off a Raccoon (Procyon lotor) at Hugh Taylor Birch State Park in Broward County, Florida on 9 November 2006.Green Iguana remain to be tested but seem logical in light of the Raccoon’s keen ability to fi nd and de-stroy nests, up to 95% of Sea Turtle nests in Florida and down to 9.4% after Raccoon removal (Stancyk 1982. In Bjorndal, K.A. [ed.], Biology and Conser-vation of Sea Turtles, pp. 139-152, Smithsonian In-stitution Press, Washington, DC; Engeman et al. 2002. Ecological Economics 42:469-478; Engeman et al. 2005. Oryx 39:318-326).  Ironically, even as the targeted management benefi ts of removal of Raccoons were complete-ly achieved at HTBSP beyond expectations, the re-lease from predation pressure of the Green Iguana may well have resulted in the unexpected ecological consequence of a biotic burst of an exotic species in this urban park.   Henry T. Smith  Florida Department of Environmental Protection  Florida Park Service  13798 S.E. Federal Highway  Hobe Sound, Florida 33455, USA   *Walter E. Meshaka, Jr.  Section of Zoology and Botany  The State Museum of Pennsylvania  300 North Street  Harrisburg, Pennsylvania, 17120-0024, USA   Richard M. Engeman  National Wildlife Research Center  4101 LaPorte Avenue  Fort Collins, Colorado 80521-2154, USA   Steven M. Crossett, Mark E. Foley, and Gary Bush  Hugh Taylor Birch State Park  3109 East Sunrise Boulevard  Ft. Lauderdale, Florida 33304, USA   *Author to whom correspondence should be addressed. E-mail: wmeshaka@state.pa.usJournal of Kansas Herpetology Number 20 (December 2006)  8

Raccoon Predation as a Potential Limiting Factor in the Success of the Green Iguana in Southern Florida

UNL | Libraries

University of Nebraska - Lincoln 
DigitalCommons@University of Nebraska - Lincoln 
USDA National Wildlife Research Center - Staff 
Publications 
U.S. Department of Agriculture: Animal and 
Plant Health Inspection Service 
December 2006 
Raccoon Predation as a Potential Limiting Factor in the Success 
of the Green Iguana in Southern Florida 
Henry T. Smith 
Florida Department of Environmental Protection, Florida Park Service 
Walter E. Meshaka Jr. 
State Museum of Pennsylvania 
Richard M. Engeman 
USDA-APHIS-Wildlife Services, s_r100@yahoo.com 
Steven M. Crossett 
Hugh Taylor Birch State Park 
Mark E. Foley 
Hugh Taylor Birch State Park 
See next page for additional authors 
Follow this and additional works at: https://digitalcommons.unl.edu/icwdm_usdanwrc 
 Part of the Environmental Sciences Commons 
Smith, Henry T.; Meshaka, Walter E. Jr.; Engeman, Richard M.; Crossett, Steven M.; Foley, Mark E.; and 
Bush, Gary, "Raccoon Predation as a Potential Limiting Factor in the Success of the Green Iguana in 
Southern Florida" (2006). USDA National Wildlife Research Center - Staff Publications. 448. 
https://digitalcommons.unl.edu/icwdm_usdanwrc/448 
This Article is brought to you for free and open access by the U.S. Department of Agriculture: Animal and Plant 
Health Inspection Service at DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion 
in USDA National Wildlife Research Center - Staff Publications by an authorized administrator of 
DigitalCommons@University of Nebraska - Lincoln. 
Authors 
Henry T. Smith, Walter E. Meshaka Jr., Richard M. Engeman, Steven M. Crossett, Mark E. Foley, and Gary 
Bush 
This article is available at DigitalCommons@University of Nebraska - Lincoln: https://digitalcommons.unl.edu/
icwdm_usdanwrc/448 
Raccoon Predation as a Potential Limit-
ing Factor in the Success of the Green 
Iguana in Southern Florida 
  The Green Iguana, Iguana iguana, is a well es-
tablished, large-bodied, exotic species in Flori-
da (Meshaka et al. 2004a. The Exotic Amphibians 
and Reptiles of Florida, Krieger Publishing Compa-
ny, Malabar, Florida. 155 pp.; Meshaka et al. 2004b. 
Iguana 11:154-161). Limiting factors of populations 
and causes of Green Iguana mortality in Florida are 
poorly understood and the only documented pred-
ators are the domestic dog (Canus familiaris) (Me-
shaka et al. 2004a), Yellowcrowned Night-heron 
(Nyctanassa violacea) (Engeman et al. 2005. Her-
petol. Rev. 36:320), Florida Burrowing Owl (Athene 
cunicularia fl oridana) (McKie et al. 2005. Florida 
Field Nat. 33:125-127), and an unidentifi ed species 
of hawk (HTS pers. obs.). Here, we report the fi rst 
documented predation of a juvenile Green Iguana 
by a Raccoon (Procyon lotor) in a southern Florida 
state park. Additionally, we provide strong evidence 
of Green Iguana population density and recruitment 
suppression by Raccoons.
 Hugh Taylor Birch State Park (HTBSP) is a small, 
urban park located in Broward County, Florida, USA, 
within the City of Ft. Lauderdale. It consists of 56.7 
ha of uplands and 14.2 ha of freshwater and tid-
al wetlands for a combined total of 70.9 ha. HTBSP 
is completely encapsulated by urban infrastructure, 
and the Intracoastal Waterway (a large bulkheaded 
canal) truncates the entire western boundary. 
 At ca. 1130 h on 16 October 2006, a sunny day, 
temperature ca. 85°F, HTBSP Park Rangers SMC 
and MEF observed a Raccoon chase a ca. 20 cm SVL 
Green Iguana out of maritime hammock on to one 
of the park roads. The iguana cut back across the 
road surface apparently trying to reach the safety of 
trees/ woodland cover, and the Raccoon then caught 
it in its jaws and carried it back into the hammock. 
SMC estimated the entire sequence of events to cov-
er less than 15 seconds. This observation brings the 
list of known predators of invasive Green Iguana in 
Florida to fi ve. Likewise, this predation observation 
provides additional support for our hypothesis that 
an inverted trophic pyramid dominated by artifi cially 
high midlevel predator biomass of the Raccoon ex-
erted almost complete population suppression on an 
invasive, large-bodied, lower trophic level reptile for 
at least six years. In subsequent observation, nearly 
one month later, a large male Green Iguana basking 
at 1535 h on 9 November 2006 at HTBSP was fi rst 
circled by a young Raccoon and then attacked. Its 
response (Figure 1) and follow-up behavior suggest 
that even large adults are susceptible to attack by 
Raccoons, and at least during the day, can be suc-
cessfully fended off (Figure 1). 
 Raccoon population densities in the park have 
always been artifi cially high as a direct result of un-
lawful feeding by humans. Estimates of Raccoons in 
HTBSP during the 1990s ranged from ca. 75 to 125 
animals (Smith and Engeman 2002. Canadian Field- 
Nat. 116:636-639). The threats of epizootic disease 
transmission (particularly rabies) to other wildlife, 
bites to humans, and vehicular traffi c hazards, re-
sulted in a control program in November 2000 to 
reduce these threats. The HTBSP trap and remov-
al program documented an absolute minimum den-
sity of 238 raccoons/ km2 [ = 169 raccoons/175 
acres] (Smith and Engeman 2002. Canadian Field-
Nat. 116:636-639), which is the third highest Rac-
coon density ever reported in North America, 4-200 
times greater than the other reported rural densi-
ties of 0.9-55.6 Raccoons/ km2 (Smith and Enge-
man 2002. op cit.). 
 During the years of this extraordinary mid-lev-
el predator density, few ground-dwelling reptiles 
were observed in the park and virtually all mast 
was stripped from trees annually (HTS pers. obs.). 
The Green Iguana was fi rst opportunistically ob-
served by HTS in the park maritime hammock in 
1994 and the date of their initial introduction is un-
known; however, the very rare individuals encoun-
tered in subsequent years were always large adults 
and in arboreal situations. During frequent visits 
from 1994 to 2000 for various projects, no evidence 
of Green Iguana recruitment was found in HTBSP. 
Since 2001, and after Raccoon removal, new hatch-
lings have been observed annually and as of 2006, 
the Green Iguana has saturated the park in mixed 
size-classes in all ground, arboreal, and ruderal 
habitats (HTS and WEM pers. obs.). 
 The post-Raccoon removal spike in Green Igua-
na presence at HTBSP and the depredation of a ca. 
60 cm TL Green Iguana suggest to us the effective-
ness of the Raccoon as a potentially severely lim-
iting factor of Green Iguana abundance in south-
ern Florida. In this connection, we propose that 
predation of the nest, as well, is a mechanism for 
suppression of the Green Iguana by the Raccoon. 
The case for nest predation and its effects on the
Field Notes
Journal of Kansas Herpetology Number 20 (December 2006)  7
Figure 1. A male Green Iguana (Iguana iguana) fends off a 
Raccoon (Procyon lotor) at Hugh Taylor Birch State Park in 
Broward County, Florida on 9 November 2006.
Green Iguana remain to be tested but seem logical 
in light of the Raccoon’s keen ability to fi nd and de-
stroy nests, up to 95% of Sea Turtle nests in Florida 
and down to 9.4% after Raccoon removal (Stancyk 
1982. In Bjorndal, K.A. [ed.], Biology and Conser-
vation of Sea Turtles, pp. 139-152, Smithsonian In-
stitution Press, Washington, DC; Engeman et al. 
2002. Ecological Economics 42:469-478; Engeman 
et al. 2005. Oryx 39:318-326). 
 Ironically, even as the targeted management 
benefi ts of removal of Raccoons were complete-
ly achieved at HTBSP beyond expectations, the re-
lease from predation pressure of the Green Iguana 
may well have resulted in the unexpected ecological 
consequence of a biotic burst of an exotic species in 
this urban park. 
 
 Henry T. Smith 
 Florida Department of Environmental Protection 
 Florida Park Service 
 13798 S.E. Federal Highway 
 Hobe Sound, Florida 33455, USA 
 
 *Walter E. Meshaka, Jr. 
 Section of Zoology and Botany 
 The State Museum of Pennsylvania 
 300 North Street 
 Harrisburg, Pennsylvania, 17120-0024, USA 
 
 Richard M. Engeman 
 National Wildlife Research Center 
 4101 LaPorte Avenue 
 Fort Collins, Colorado 80521-2154, USA 
 
 Steven M. Crossett, Mark E. Foley, and Gary Bush 
 Hugh Taylor Birch State Park 
 3109 East Sunrise Boulevard 
 Ft. Lauderdale, Florida 33304, USA
 
 
 *Author to whom correspondence should be addressed. 
E-mail: wmeshaka@state.pa.us
Journal of Kansas Herpetology Number 20 (December 2006)  8


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Raccoon Predation as a Potential Limiting Factor in the Success of the Green Iguana in Southern Florida

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