The invasive spectacled caiman (Caiman crocodilus) in Florida, United States: invasion timeline, insights, and implications for Everglades restoration

Introduction

Freshwater ecosystems are highly affected by invasive species across the world resulting in significant ecological and economic impacts and conservation challenges (Diagne et al., 2021). Wetlands, lakes, and river ecosystems globally have been experiencing large biodiversity declines in past decades as a consequence of invasive species impacts (Reid et al., 2019). The reason behind these impacts is how drastically invasive species can alter ecosystems’ structure (richness, composition, and abundance) and function (trophic dynamics and interspecific competition; Gallardo et al., 2016). The successful establishment of invasive species in new environments is often linked to life-history traits (species invasiveness) as well as ecosystem invasibility (ecological opportunity), which together facilitate acclimatization and integration into invaded environment (Su et al., 2023).

The state of Florida in the United States (US) hosts one of the greatest numbers of established non-native herpetofauna globally (63 reptiles and amphibians; Krysko et al., 2016). This pattern is largely driven by the state’s tropical climate, ecosystem invasibility (i.e., disturbed habitats and altered-predator-depleted ecosystems), habitat availability, and wildlife trade industry, which has facilitated the establishment of numerous species (Fujisaki et al., 2010, 2015). This surge of non-native herpetofauna has had serious impacts on native wildlife (Mazzotti et al., 2015) and provides a real threat to the Comprehensive Everglades Restoration Plan (CERP), as it can diminish the positive effects of hydrological restoration on ecosystem biodiversity. One of these ‘of concern’ invasive species is the spectacled caiman (Caiman crocodilus), a mid-sized crocodylian from Central and South America established in Florida since the 1970s (Ellis, 1980).

The spectacled caiman is a habitat and diet generalist (Medem, 1981), making it a prolific invader likely only being limited by temperature (Brandt and Mazzotti, 1990, Campos et al., 2005) and salinity (Taplin et al., 1982). Spectacled caimans have been used in the pet trade since the 1950s leading to the introduction of the species in the US with current established populations in Florida (Ellis, 1980) and Puerto Rico (Thomas and Joglar, 1996). This species is also established in Cuba (Estrada and Ruibal, 1999) and San Andres Island, Colombia although the introduction path is less clear (Forero-Medina et al., 2006).

To fight an invasive species and understand its impact on an introduced ecosystem, the first step is to learn about the species’ biology and ecology, allowing researchers, agencies, and decision-makers to evaluate and recognize the risk of success and expansion of the species into novel and ecologically sensitive environments. Bearing this in mind, this review compiles and presents in a digestible way what we have learned about the biology and ecology of the spectacled caiman in Florida after about 70 years of invasion and around 45 of establishment, which can be of great use to managers and stakeholders currently fighting this invasive species. Our investigation included novel data on the species’ habitat and nesting preferences collected through monitoring, highlighting key environmental and biotic factors influencing potential spectacled caiman further spread into protected areas. Finally, we identify knowledge gaps and research priorities essential for future investigations into the impacts of spectacled caiman on the food webs of invaded ecosystems.

Spectacled caiman overview

The spectacled caiman has one of the widest ranges of all crocodylians in the Americas, spanning 17 countries from Mexico to Brazil (Figure 1a; Balaguera-Reina and Velasco, 2019). This species is native to mainland Central and South America with few insular native populations in Trinidad and Tobago and Galagos Island in Colombia (Medem, 1981, 1983). Spectacled caimans are mid-sized crocodylians, rarely exceeding 2.5 m in total length, with a broad skull topped with supraocular ridges and a body armored with osteoderms (Figure 2; Medem, 1981). Spectacled caimans inhabit a variety of ecosystems throughout their native range from swamps, marshes, and water bodies in forested areas to manmade water reservoirs and canals in disturbed, urban, and agricultural areas and range in elevation from 0 to 1,000 m above sea level (Balaguera-Reina and Velasco, 2019). This species also has a broad diet (diet generalist), which includes insects, fish, reptiles, birds, and mammals (Medem, 1981; Ayarzagüena, 1984).

Invasion path and origin

Spectacled caiman gained popularity in the pet trade in the US in the 1950s in response to the American alligator (Alligator mississippiensis) trade-ban (Figure 3; Moore, 1954). Early records of spectacled caiman in the wild in Florida started in the 1960s with locals reporting individuals in Palm Beach County (King and Krakauer, 1966). In the 1970s, spectacled caimans were first found and removed from the Homestead Air Reserve Base (HARB) and by 1980 it was determined that the spectacled caiman was established (reproducing and growing by itself in the wild) in South Florida (Ellis, 1980). Since then, records of spectacled caiman in South Florida ecosystems have increased in areas such as Miami canal system and Tamiami Trail (Wilson and Porras, 1983), adjacent to Everglades National Park (ENP; Butterfield et al., 1997, Meshaka et al., 2000), Biscayne Bay coastal wetlands, the C-111 spreader canal western project (Godfrey et al., 2023), and as far north as Port St. Lucie (EDDMapS, 2025).

Spectacled caimans have been and are still active in the pet trade in the US and Florida as the species is not currently listed as prohibited, allowing importation, transport, trade, possession, and breeding in the state (Florida statutes 379.3761 and 379.3762). Most spectacled caimans imported since 1950s came from Colombia, making it the main source of spectacled caiman introduced in Florida (Ellis, 1980). A total of 330,705 spectacled caimans were imported into the US from 1977 to 2024 (CITES Secretariat and UNEP-WCMC, 2022), from which a total of 18,525 were imported directly into Florida between 1999 and 2018 (USFWS-LEMIS) with Miami as main port of entrance (18,180 records). Origin of imports in Florida have varied since 1999 from countries that are part of the native range of the species (Guyana -12,211 exports, Guatemala -4,650 exports, Colombia -1,268 exports) to countries where the species is not native (South Africa -223 exports and Italy -72 exports). Yearly data showed a peak in 1999 (10,841 individuals) and a very low number in 2018 (6 individuals).

Molecular work done by Roberto et al. (2021) analyzing samples from spectacled caimans collected between 1977 and 2013 corroborated Colombia as a main source of introduced spectacled caimans in Florida, describing the Magdalena River basin as the most likely area of origin. Parks et al. (2024) complemented this work by analyzing a larger and more recent pool of samples showing evidence of multiple introduction events (at least 3) in South Florida based on haplotype diversity and haplotype distribution. These authors also recorded the presence of two distinct molecular lineages of spectacled caiman in South Florida originating from at least two different regions: the Magdalena River Basin in Colombia (putative Caiman crocodilus fuscus) and the Upper Branco River Basin in northern Brazil-southern Guyana (putative Caiman crocodilus crocodilus). The spectacled caiman lineage from northern Brazil-southern Guyana is currently localized and only present bordering the Everglades National Park (C-111 spreader canal and 8.5 square mile area; Figure 1b, c) whereas the spectacled caiman lineage from Colombia is more broadly distributed from Everglades Holiday Park to HARB.

Habitat and diet in Florida

Spectacled caimans in South Florida are mainly found in manmade habitats such as canals, artificial ponds/lakes, and ditches, although recent records have documented occurrence in natural areas such as marsh and slough areas within Water Conservation Area (WCA) 3 and ENP (specifically in Shark River Slough). Habitat overlap with native crocodylians (American alligators and American crocodiles -Crocodylus acutus) have been observed across the Biscayne Bay Coastal Wetlands, WCA 3, and ENP, although more commonly with American alligators than with American crocodiles. There are no specific studies on spectacled caiman habitat use in South Florida, so it is not clear whether this species has a habitat preference and how much they overlap with native crocodylians. Nonetheless, Godfrey et al. (2023) found that spectacled caimans were most observed in either shallow-water habitats such as marshes and ditches or in deep-water habitats such as canals and ponds/lakes across South Florida.

There are only few studies assessing spectacled caiman diet in South Florida. Ellis (1980) reported that the spectacled caiman diet at HARB shifted by size, with juveniles preying upon amphibians, small fishes, and invertebrates, and adults preying upon larger fish and birds. Krysko et al. (2010) and Friers and Flaherty (2016) reported spectacled caimans predating on a non-native walking catfish (Clarias batrachus) and native blue land crab (Cardisoma guanhumi). A more recent study done by Godfrey et al. (2025) complemented previous studies, reporting spectacled caimans preying upon at least 36 species (Table 1); from arachnids to mammals, including native (25) and non-native (11) species. They also found that adult caimans had higher dietary diversity and evenness compared with subadults and juveniles, females have higher diversity and evenness than males, and caimans captured in Florida’s dry season (February through May) exhibited higher diversity and evenness than those captured in the wet season (September through November).

Table 1. Spectacled caiman prey items identified in Florida (modified from Godfrey et al., 2025).

Although there are no records of spectacled caimans preying upon any endangered or threatened species, water snakes (Nerodia sp.) have shown a steep decline in the last decade across main park road at ENP (Whelpley pers. comm.), which can be of concern as it was also found as a common prey item for spectacled caiman (Godfrey et al., 2025). Even though this decline cannot be directly linked to spectacled caimans, knowing that spectacled caiman prey upon water snakes provides another layer of concern on what could be causing the population reduction of these native species within ENP. The trophic breadth identified in spectacled caimans in Florida implies that it can be exerting negative pressure on the abundance and availability of food resources for other native species. The reduction of local prey populations could generate cascading effects that alter key ecological processes and compromise community stability (Mooney and Cleland, 2001).

Reproduction and nesting

Data indicated that spectacled caimans have been reproducing in South Florida since the late 1970s. However, little information has been collected regarding reproduction and nesting of this species in Florida. Ellis (1980) reported the only confirmed caiman nest recorded in South Florida at HARB, which contained 37 eggs averaging 60 mm in length, 37 mm in width, and 45 g. Incubation time was 85 days with hatching likely in September based on when hatchlings were observed at HARB, although this was not confirmed by the author. Hatchlings measured on average 21 cm in total length and weighed 29 g.

Mazzotti and Miller (2023) recorded what seems to be a caiman nest adjacent to Cemex Lake in mid-September 2023, 48 m away from the location where seven spectacled caiman hatchlings were captured. This nest was composed of mounded Australian pine (Casuarin sp), needles (Figure 4a). Eggshell fragments were found within this nest, in addition to an intact-hollow egg (60.60 mm length, 39.01 mm width; Figure 4b) that matches known spectacled caiman egg dimensions. Additionally, there were no other species of crocodylian hatchlings found within this area where/when the nest was found, providing more support to suggest that this was a caiman nest. Godfrey et al. (2023) concluded, through removals and necropsies of spectacled caiman year-round, that caiman nesting in South Florida occurs from mid-June to mid-July and hatching appears to happen in early September fairly matching what have been reported by the species in the native range (Thorbjarnarson, 1994).

Control efforts and potential impacts on Everglades restoration

Few and sparse efforts to control/eradicate spectacled caimans have been documented in South Florida since their establishment in the 1970s. Ellis (1980) reported the first extirpation effort at HARB between 1977–1978 removing a total of 44 spectacled caimans. No indications of continual removals can be tracked until 2009 when the US department of Agriculture personnel at HARB started recording caiman removals, totaling 44 spectacled caimans removed up to 2019. This means a total removal of 88 spectacled caimans from HARB across a ~40-year period. Opportunistic removal effort by authors started in 2012, and a systematic removal effort was consolidated in 2017 (Godfrey et al., 2023), which is still on going, removing (up to November 2025) 342 spectacled caimans from CERP project footprints, specifically, Biscayne Bay Coastal Wetlands, C-111 Spreader Canal Project, and ENP. This is currently the only active effort to control or manage spectacled caiman populations and their effects on Everglades ecosystems in Florida.

An expert panel to determine research and management priorities for Florida’s invasive reptiles identified spectacled caiman as having a “highest impact concern” (Engeman and Avery, 2016). As Everglades restoration proceeds two concerns are preeminent, how will spectacled caimans in and near CERP projects respond to restoration activities and how will this response affect valued ecological components such as American alligators and American crocodiles? These concerns take on particular significance when considering the situation in the Amazon basin, where evidence suggests that spectacled caiman may be limiting the recovery of black caiman (Melanosuchus niger) through interspecific competition (Laverty and Dobson, 2013). Furthermore, Thorbjarnarson and Hernandez (1992) hypothesized that the expansion of spectacled caiman populations into areas formerly occupied by Orinoco crocodiles (Crocodylus intermedius) prior to removal inhibited the reintroduction of Orinoco crocodiles in Venezuela. Although there are not specific studies quantifying interspecific competition of spectacled caimans and native crocodylians (American crocodiles and American alligators), it is hypothesized that large spectacled caiman populations could limit the recovery of native crocodylians hampering Everglades restoration objectives. Further research quantifying (magnitude and direction) spectacled caimans’ effects on native crocodylian populations around restoration projects such as Biscayne Bay Wetlands Complex, C-111, Frog Pond, and 8.5 square mile area are warranted.

The goal of the Biscayne Bay Coastal Wetland Project is to restore historical patterns of freshwater flow to Biscayne Bay to reduce salinity and hypersaline events in the mangrove fringe (U.S. Army Corps of Engineers, 1999, 2023). American crocodiles are predicted to increase in growth, survival, abundance, and body condition (RECOVER, 2009). However, lower salinities may also attract caimans, potentially limiting the response of crocodiles. Caimans also pose a threat to alligators and ENP.

The C-111, Frog Pond, and 8.5 square mile area restoration projects are all at or near the headwaters of Taylor Slough in ENP. Spatially, invasion of Taylor Slough by caimans is one levee away and may already have occurred. However, no surveys have been conducted in this area for caimans or alligators. The current seasonal nature of the wetlands in Taylor Slough makes them suitable habitat for caimans, while the water management infrastructure of ponds, canals, and marshes designed for restoration purposes provides ideal current habitat for caiman (Godfrey et al., 2023). The distribution and abundance of alligators and caimans in Taylor Slough should be determined and monitored as ecosystem restoration proceeds.

Remarks and conclusions

Contrary to what was previously assumed, spectacled caiman populations in South Florida have different origins (Colombia and northern Brazil-southern Guyana), potentially increasing their chances of surviving and thriving in the environment due to an increased genetic diversity if admixture. We hypothesized that the reason for these two populations remaining spatially delimited is that the C. c. crocodilus (northern Brazil-southern Guyana) is a more recent introduction that has not spread yet into areas where C. c. fuscus is present. Nonetheless, admixture is expected if these populations are not managed and let to grow. We also hypothesized that a broader genetic spectrum (more haplotypes/genetic lineages) may be found in Florida as spectacled caiman importations in the last two decades have covered a wide range of countries (e.g., Guatemala). Thus, it is of high interest for management purposes to understand the genetic diversity of spectacled caimans currently inhabiting wild areas in Florida but also the ones in captivity or traded as it could be a potential input if not appropriately managed. This represents a crucial factor, as determining whether ongoing introductions are happening would allow us to identify the potential geographic origins of these animals and, in turn, recognize key factors that may be hindering the successful eradication of the species. Future genetic studies are needed to thoroughly evaluate the genetic variability of spectacled caimans in Florida, providing critical insights for effective management and control strategies.

Spectacled caimans have been recorded and removed from most habitats present within the CERP footprint, using new habitats within CERP projects as they expand (Godfrey et al., 2023), which conflicts with CERP goals and objectives (National Research Council, 2015). Spectacled caimans have the potential to impact South Florida’s ecosystems by competing with native crocodylians as well as other predators that rely on aquatic/terrestrial prey as well as by preying upon threatened or endangered species (e.g., young American crocodiles, indigo snakes -Drymarchon couperi). Efforts should be made to test these hypotheses by researchers and managers as implications of spectacled caiman impacts in the Everglades are currently unquantifiable. Likewise, ecological and physiological evidence must be collected to analyze niche overlap with respect to native crocodylians, providing the biological information needed to quantify impacts.

It is expected that CERP projects will have a positive effect on freshwater habitats, recovering water table, flow, and bringing a more natural water dynamic, which can also provide more suitable habitat for uncontrolled spectacled caiman populations. All this highlights the need for more thorough efforts to remove, control, and monitor invasive populations that can be favored by CERP modifications. It was defined by an expert panel that evaluated research and management priorities for Florida’s invasive reptiles that spectacled caimans have a “highest impact concern” (Engeman and Avery, 2016), once more highlighting the need for robust monitoring and control efforts.

The number of studies on spectacled caiman in Florida has increased in recent years. However, a substantial gap remains in our understanding of key attributes needed for effective management in South Florida. Aspects such as spectacled caiman movements, activity areas, and habitat use are fundamental, as they provide the basis for implementing control measures that spatially and temporally target habitats that facilitate dispersal and establishment (Clout and Williams, 2009; Holway and Suarez, 1999). A clearer understanding of these spatial and temporal dynamics would not only improve removal efficiency but also help anticipate potential range expansions and ecological impacts.

Evidence from its native range shows that spectacled caimans can migrate and/or aestivate depending on hydrological conditions (Medem, 1981; Bonilla-Liberato et al., 2023). Such information is critical in South Florida where seasonal changes in water levels are common, as it would reveal whether caimans remain in their usual activity areas during low-water periods through aestivation, or instead disperse to new areas in search of suitable water conditions. Understanding these dynamics is crucial for improving the timing and location of removal efforts in relation to location and hydrological cycles.

Based on our review, we conclude that the management approach most effective for control or extirpation of caimans would be to conduct consistent, persistent, and thorough removal surveys both along standardized routes and opportunistically. In particular, surveys should be conducted during the nesting season and during water level fluctuations which may increase detection and access. Nest surveys should be conducted during mid-July to late-August to optimize removal of unhatched nests and attendant females. If the desired condition of control or extirpation is met (no encounters for several years) the monitoring should continue to ensure that the desired condition is maintained.

There is a potential for spectacled caimans to have a negative impact on Everglades ecosystem restoration. The creation of ponds, canals, and marshes as part of restoration infrastructure provides habitat for caimans immediately adjacent to (sometimes within) natural areas meant to be restored, while changes in environmental conditions (in this case lower salinities within the restored site) may make habitats more suitable for caimans. This emphasizes the need for continued removal efforts and monitoring with CERP project footprints.

Correction note

A correction has been made to this article. Details can be found at: 10.3389/famrs.2026.1895071.

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Footnotes

Edited by: Sara L Ashpole, St. Lawrence University, United States

Reviewed by: César P. Ley-Quiñónez, National Polytechnic Institute (IPN), Mexico

Marco Suárez-Atilano, National Autonomous University of Mexico, Mexico

Mauricio González Jáuregui, Autonomous University of Campeche, Mexico