By Lelani Del Pinto & Samuel Fisher
Southern California has remained relatively unaffected by invasive reptiles for the past few decades. While there have been few invasive species noted, Californians use of citizen science tools has made it easier to detect novel invasive species. One source of invasive species passage is plant nurseries. Multiple sources studying invasive species across the world have noted they have played a major role in various A. sagrei invasions.
At our sites we found plant nurseries at three out of the five survey locations. Anolis sagrei was first detected during an invasive lizard survey in which we (Lelani Del Pinto and Samuel Fisher) were determining the spread of parthenogenetic whiptails (Aspidoscelis sonorae) from Arizona, when we stumbled upon the unexpected A. sagrei population. A new survey began immediately among a tiny strip mall and not one but approximately 30 A. sagrei were seen.
With a new mission in hand, we next turned to iNaturalist which showed a few scattered records of A. sagrei across Orange County. None of the citizen records were from the strip mall at which we conducted our first survey. Doing a literature search, we found one short note about A. sagrei in California, but no other publications for the state. We established five separate sites based on iNaturalist records as well as the other population we found. After that we surveyed all of the sites and accounted for all of the lizard species seen.
Each site with citizen records proved to have at least a couple of hectares of invaded A. sagrei land. Our methodology was focused on trying to understand the total distance the separate A. sagrei populations had spread; by trying to create a minimum convex polygon, we hoped to get an idea about the minimum size of each of these disjunct populations.
As we were already keeping track of all lizard species we found, we quickly noticed a somewhat problematic trend. It seemed that in localities where A. sagrei was present, the native Sceloporus occidentalis was nowhere to be found. Due to the lack of presence of S. occidentalis in the surveyed sites in which A. sagrei was observed, we think there is reason to pursue further surveying to ensure our native western fence lizard is not threatened by this invader.
While the full extent of the invasion is yet to be determined, further studies could prove the issue is more problematic than anticipated, especially if more A. sagrei come into California and eventually establish through the help of the nursery trade. Secondly any downstream effects caused by invasive A. sagrei should be closely watched because extirpations of S. occidentalis may prove troublesome. Sceloporus occidentalis is known to have an important role in our ecosystem and reduces lyme disease.
The results of our study help to show that within southern California, A. sagrei has the potential to become an invader as it has in many other places such as Florida, Hawaii, and Texas. The impact of the potential A. sagrei invasion in southern California will hopefully be further studied and handled appropriately. We hope you check our paper out to learn the details about where brown anoles have recently spread!
References
Fisher SR, Del Pinto LA, Fisher RN. 2020. Establishment of brown anoles (Anolis sagrei) across a southern California county and potential interactions with a native lizard species. PeerJ 8:e8937 https://doi.org/10.7717/peerj.8937
Mahrdt CR, Ervin EL, Nafis G. 2014. Geographic distribution: Anolis sagrei (Cuban Brown Anole). Herpetological Review 45:658–659.