Anoles of South America Part 3: Introduced Anoles

In North America, especially in places like Florida, invasions of introduced species have revealed novel insights into the competition between species as well as the formation of non-analog species assemblages during such events. Anolis lizards, in particular, have demonstrated a strong ability to invade novel environments possibly even displacing native species in many cities in the United States. Yet the same appears not to be true in South America possibly because similar invasions are only just now occurring. In previous posts I considered diversity of cis– and trans-Andean South American anoles. In this post, I will review what can be inferred about the introduced species of anoles in South America using data accumulated on iNaturalist.org.

Certain introductions have been reported, but not yet observed on iNaturalist, such as Anolis sagrei in Rio de Janeiro (Oliveira et al. 2018). However, there are a handful of examples of anole introductions in South America that can be explored in terms of their progress as becoming invasive. As it turns out, most of the anole introductions appear to be fairly early along in the process of invasion making their documentation a useful exercise for future study by anole enthusiasts.

Despite the lowland Amazon rainforest’s vast size, introduced anoles have not been an issue there until very recently. Where introductions do appear to be occurring in South America, they seemed to have started in coastal cities. The first area of interest are the coastal cities in the northeast of South America.

Anolis aeneus in Guyana

Anolis aeneus has been known from Guyana for several decades and is possibly over a century old (review by Williams 1977, see also Schwartz and Henderson 1991). This species appears to be established in Georgetown, Guyana, and has been observed on iNaturalist since 2012. By the end of 2024 there were still only 34 observations of this species in all of Guyana, but this includes at least a pair of observations away from Georgetown in the interior of that country. So, while A. aeneus is considered introduced in Guyana (see image below), it does not appear to be far along in the process of invasion at this point or moving especially rapidly.


Figure above shows all iNaturalist observations of introduced anoles in Guyana, Suriname, and French Guiana.

 

Anolis marmoratus and A. sagrei in Suriname and French Guiana

A larger ongoing invasion appears to involve the introduced Guadeloupean Anole (Anolis marmoratus) in French Guiana (see image above). Anolis marmoratus was first reported in French Guiana in 1975 as already well established in Cayenne, French Guiana (Hoogmoed and Lescure 1975). On iNaturalist, this species has been reported in the vicinity of Cayenne since at least 2004 but with only a handful of observations each year until very recently.

Annual observations of A. marmoratus from 2021-2023 were 7, 6, and 8, respectively, including one or two additional observations in Kouro about 40 km along the coast to the northwest. However, in 2024 observations jumped to 18 and came from every neighborhood of the twin cities of Cayenne and Remire-Montjoly as well as another seven observations in Roura 15 km to the south and eight in Kouro. While A. marmoratus appears to be established and spreading in French Guiana, it might begin experiencing competition from another well-known invasive anole that appears to be recently introduced in the area: Anolis sagrei.

The first report of Anolis sagrei in northeast South America came from Paramaribo, Suriname, in 2022 when a single observation was added to iNaturalist from within that city. This species was not among those listed as introduced to Suriname by Hoogmoed (1980), although other species of anoles were mentioned, but not yet observed on iNaturalist in Suriname.

In 2024, three observations of A. sagrei were made in the same area of French Guiana. In both cases, it is too early to tell if these are established populations and if they will spread, but the known invasive habits of A. sagrei in places like south Florida make this seem a likely occurrence.

Anolis sagrei in Guayaquil, Ecuador

In western South America, there have been occasional single observations of Anolis sagrei in places like Zamona, Ecuador, along the Napo River in the Amazon occurred in 2022. However, this observation has not been corroborated so far. Until additional observations are made, it is not possible to determine if we are seeing the beginnings of invasions in any of these places. Yet, A. sagrei already has a well-established foothold in another South American location that is worth examining: Guayaquil, Ecuador, reviewed recently by Narváez et al. (2024)(see image below).


Figure above shows all iNaturalist observations of Brown Anoles in the vicinity of Guayaquil, Ecuador. Image courtesy Jaime Camacho via iNaturalist.

Anolis sagrei was first observed on iNaturalist in 2007 in a park in Guayaquil, in southwestern Ecuador, but first reported in about the year 2000. This observation was of a lizard on the peninsula formed by the confluence of the Daule, Babahayo, and Guayas Rivers. It was not observed again until 2016 in that same park, but soon it became apparent it was probably there all along, which is why continued monitoring is essential for understanding invasions.

In 2017 Anolis sagrei was observed six additional times, but had now expanded to occur in several different places in the city having moved about 4 km from the original location and even jumped the Daule River. That same year also saw a single observation of A. sagrei in the northwestern Ecuador city of San Lorenzo, but this has never been repeated so it is hard to tell if this the beginnings of a new invasion or not. By 2018 it was at least 6 km from the original site and in 2019 A. sagrei was observed 17 times having reached the forested outskirts of Guayaquil to the west some 10 km from original location. Thus, even as late as 2019, A. sagrei appears to have been in the early stages of the invasion, but with a big leap forward in 2020.

In 2020, A. sagrei appears to have begun moving along the roads to the north and west of Guayaquil and tripled its occurrence to 49 observations in and around the city. Half of those observations in 2020 occurred on the peninsula where the species was first noted in iNaturalist. But 2020 also saw a leap for this species with an observation for the first time in Portoviejo nearly 200 km to the northwest of Guayaquil.

The next year, 2021 saw another 50 observations, with over half occurring outside the area where they were first noted. In that year, the suburbs of Guayaquil to the north and west of saw strong growth in observations. Similarly, 2022 added another 48 observations in the vicinity of Guayaquil. In 2022, the population had reached a zoo near Victoria 15-20 km to the north of Guayaquil. Thus, by the early 2020’s A. sagrei had become firmly established in the greater Guayaquil areas and this species took another leap forward in 2023.

In 2023, 85 observations spanned nearly every neighborhood of Guayaquil and its outskirts. Interestingly, even by 2023 A. sagrei had still not jumped the Guayas River to Duran on the east bank. Nor had it colonized the forested reserve of Isla Santay in the Guayas River between these two cities. However, in 2023 A. sagrei did make a big leap northwest to the coastal city of Manta about 20 km west of the aforementioned Portoviejo.

Guayaquil continued to be the center of observations for A. sagrei in 2024 with another 52 observations, but now observations are being reported elsewhere along the coast including Olon, which is about 100 km west of Guayaquil. However, the observations near Manta, Portoviejo, and San Lorenzo have not been repeated so far. Nor has the species appeared to jump the Guayas River to either Isla Santay or Duran.

Isla Santay is of particular interest because of the known population of the native Anolis festae that occurs there. If A. sagrei were to arrive on Santay it could lead to the extirpation of A. festae at that site or at least a novel competitive environment for that native anole. This is where directing a community of observers, such as on iNaturalist, might be of service to monitor these areas for the novel spread of A. sagrei as well as the persistence of A. festae.

If we take 2007 as the initial year of introduction, A. sagrei appears to be expanding its range at about 5 km per year, but with some leaps out beyond that probably via human-aided dispersal. And even though community data such as provided by iNaturalist are not controlled for in terms of effort, they do provide a fascinating window into an ongoing invasion by a known invader. However, A. sagrei isn’t the only invader of South America.


Figure above shows iNaturalist observations of Brown Anoles in Guayaquil, Ecuador binned in three-year intervals.

 

Anolis porcatus in Santos, Brazil

A lesser-known invasion of South America appears to involve Anolis porcatus in southeastern Brazil. This invasion appears to be even more recent than A. sagrei in Guayaquil and is worth detailing. Anolis porcatus was first observed on iNaturalist in Santos, Brazil (a coastal city just south of São Paulo) in March 2016 at about the same time it was reported in the literature (Prates et al. 2016, Samelo and Barella 2016). This was the only observation of this introduced species until 2018 when five additional observations recorded this species in three separate locations in São Vincente 8-10 km to the west of the original location.


Figure above shows all iNaturalist observations of Cuban Green Anoles in the vicinity of Santos, Brazil. Image courtesy Nereston Camargo via iNaturalist.org.

In 2019, an additional nine observations of A. porcatus occurred in Santos and São Vincente. Thus, by the end of 2019 it appears A. porcatus had established in four different locations. However, observations were still only occasional at this time.

In 2020 A. porcatus jumped to Cubatão, a city another 5 km to the north of São Vincente, and in 2021 it jumped to Praia Grande 5-6 km along the coast to the southwest of São Vincente. By 2023 there were another 21 observations of this species in and around the area including the forested outskirts to the north of Cubatão. In 2024 another 18 observations of the species suggested A. porcatus was now firmly established around Santos.

In addition to the above observations, in October 2024 A. porcatus was noted for the first time southwest along the coast near Itanhaém about 45 km from the original source location in Santos. Thus, similar to A. sagrei in Ecuador, A. porcatus appears to be making leaps from city to city, possibly via human-aided dispersal.

If we take 2016 as the initial year of introduction, A. porcatus appears to be expanding its range at about 5 km per year and should reach the outskirts of São Paulo in another year or two if this rate holds. This introduction does not yet appear to be affecting any of the native anoles since the closest natural populations of any Anolis occur in Rio de Janeiro several hundred km to the northeast.


Figure above shows iNaturalist observations of Cuban Green Anoles in Santos, Brazil binned in three-year intervals.

When A. porcatus does reach Rio, it could begin competing with the native Amazon Green Anole (A. punctatus), which looks and behaves very similarly. The protected forested corridor along the coast means that there is no meaningful barrier to movement from São Paulo to Rio for the introduced A. porcatus at the moment. Likewise, it seems only a matter of time before A. porcatus moves southwest along the coast toward Curitiba some 200 km away.

Summary

To summarize, there have not been many instances of introduced anoles in South America for whatever reasons. Nearly all of these start near the coast, likely because invaders are hitching rides in shipping containers or other ocean transport. Right now, the most advanced invasion seems to be taking place in Guayaquil, Ecuador with more recent invasions likely taking place in French Guiana and near São Paulo. Each of these introductions appears to be in the early days of invasion with establishment only clear in and around those locations where originally observed. The expansion of introduced species seems to involve expanding within local areas of these cities and only then expanding by leaps and bounds to nearby cities after several years of establishment. With the rise of community-based observations on platforms such as iNaturalist we can make predictions about when these introduced species will arrive in nearby cities. Likewise, we can leverage the local populace for use in environmental monitoring to better understand potential invasive dynamics of these introduced species for which anoles serve as a useful model system. Whether highly invasive anoles such as A. sagrei can ever invade species-rich environments such as the Amazon or other non-coastal areas remains to be seen. Yet platforms such as iNaturalist may allow us to observe such events in real time if the community of observers can be cultivated and maintained.

Literature cited

Hoogmoed, M.S. 1980. Introduced species of reptiles in Surinam. Notes on the herpetofauna of Surinam VIII. Amphibia-Reptilia 1:277-285.

Hoogmoed, M.S., J. Lescure. 1975. An annotated checklist of the lizards of French Guiana, mainly based on two recent collections. Zoologische Mededelingen 49:141-171.

Narváez, A.E, F. Ayala-Varela, S. Cuadrado, K. Cruz-García, M.H. Yánez-Muñoz, L. Amador. 2024. Updated distribution of the brown anole in continental Ecuador: a case of urban spaces favoring the establishment of an opportunistic exotic species. BioInvasions Records 13:373-384.

Oliveira, J.C.F., T.M. Castro, M.C. Drago, D. Vrcibradic. I. Prates. 2018. A second Caribbean anole lizard species introduced to Brazil. Herpetology Notes 11:761-764.

Prates, I, L. Hernandez, R.R. Samelo, A.C. Carnaval. 2016. Molecular identification and geographic origin of an exotic anole lizard introduced to Brazil, with remarks on its natural history. South American Journal of Herpetology 11: 220-227.

Samelo, R.R., W. Barrella. 2016. Geographic distribution: Anolis porcatus (Cuban Green Anole). Herpetological Review 47:256.

Schwartz, A., R.W. Henderson. 1991. Amphibians and Reptiles of the West Indies: Descriptions, Distributions, and Natural History. Univ. Florida Press, Gainesville.

Williams, E.E. 1977. Anoles out of place. The Third Anolis Newsletter. pp. 110-118.