Following the Expansion of Anolis sagrei in Ecuador

While reading reports on the colonization events of the brown anole and its impacts on local fauna, I never thought I would have the chance to see this lizard, so interesting from an ecological point of view, in the wild. However, years ago, thanks to an invitation from a colleague in Guayaquil, I participated in the first report of the occurrence of Anolis sagrei in Ecuador. At that time, only a few individuals were seen, and encounters were casual in two specific locations. However, since 2018, I have had the opportunity to start monitoring the brown anole in Guayaquil, Guayas province.

In past experiences searching for native anoles over five years in forests and other vegetation formations in Ecuador, I knew the local anoles are animals that hide a lot and are not seen frequently. I was used to recording few encounters over long distances (finding five or at best 10 individuals after several days and nights of searching). To my surprise, the scenario changed in Guayas. During our first excursion, we found more than ten individuals in five minutes within an area of five square meters in the middle of the city. These animals did not hide or try to escape; instead, they initiated displays.

This marked the beginning of our efforts to search for them not only in the areas reported by Amador et al. (2017) but also in various places throughout the city. This included garden areas and urban parks, as well as remnants of forest found in the city’s outskirts. Thanks to these observations, we gathered information on their diet, behavioral activity, and ecology, which will surely help us understand why they are so successful in these environments.

In this study, we managed to report not only the sites where we personally searched but also incorporated casual observations from citizens using citizen science tools like iNaturalist. Thanks to this, we now know that the species has spread to different provinces in the country (Esmeraldas and Manabí provinces), including one in the Amazon region (Orellana province). It’s interesting that thanks to this tool, we included points where we would not have thought to look for them. Additionally, the brown anole is very charismatic, and many people have felt an affinity and attraction to the little creatures that move their dewlaps, hence fortunately, the records provided by citizens were of good quality, allowing us to corroborate identification and data accuracy.

The adaptability of this lizard is evident in its ability to occupy different spaces, including urban areas such as parks, gardens, and natural areas along riverbanks. Consequently, new questions arise: where did these animals come from? How long ago did they arrive? Does their current distribution result from one or multiple introduction events? What impact will this lizard have on local species in terms of displacement or competition? We know it is a dominant species, but we still lack indications of its effect, particularly in Isla Santay reserve, where two other native species are found in sympatry (Cruz-García et al. 2023). Since we registered that several families of insects that are considered agricultural pests are part of their diet, may they have a positive or negative impact on humans? (Narvaez et al. 2020)

We feel obligated to review how the dispersal processes of this lizard can be controlled. However, more information on the species’ actions is needed to start recommending control measures or other actions at the local level. These lizards have been found in nurseries around the city, which are also used to support reforestation efforts in areas of native vegetation, facilitating the dispersal processes and the possible ecological consequences associated with their spread.

In sum, we have a love-hate relationship with the brown anole. As behavioral ecologists, we recognize that Anolis sagrei represents an excellent model for studying the biological invasion process, and we hope to share more about our findings from the past seven years soon. However, we are also concerned about how to manage this species. Probably, containment or eradication measures may need to be established to prevent problems experienced in other regions from occurring with Ecuadorian anoles.

We want to share our experience with other enthusiasts of this fascinating invader and our efforts to understand its dispersal mechanisms, ecological and behavioral adaptations, and the strategies suggested for its management. By doing so, we hope to collaborate and contribute to a broader understanding and effective management of the brown anole.

You can read the full article here.

I would like to acknowledge the invaluable contribution of Fernando Ayala-Varela to this blog.

REFERENCES

Amador, L., Ayala-Varela, F., Nárvaez, A. E., Cruz, K., & Torres-Carvajal, O. (2017). First record of the invasive brown anole, Anolis sagrei Duméril & Bibron, 1837 (squamata: iguanidae: dactyloinae), in South America. Check List, 13(2), 2083-2083.

Cruz-García, K., Barreno, M., Cuadrado, S., Moretta-Urdiales, M. D. M., Molina-Moreira, N., Salas, J. A., … & Narváez, A. E. (2023). Amphibians and reptiles of Isla Santay (Durán, Ecuador). Check List, 19(3), 347-369.

Narváez, A. E., Ghia, T., Moretta-Urdiales, M. M., & Moreira, N. M. (2020). Feeding habits of Anolis sagrei, an introduced species, in urban ecosystems of Guayas Province. Urban Ecosystems, 23(6), 1371-1376.

Narváez, A. E., Ayala-Varela, F., Cuadrado, S., Cruz-García, K., Yánez-Muñoz, M. H., & Amador, L. (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(2), 373-384.