Invasive Common Wall Lizard Continues to Spread, Saanich

Observation by Eva Gibbons:

A single, invasive common wall lizard (Podarcis muralis) observed along Epsom Drive, likely introduced by accidental transportation in 2020. I have lived along Epsom Drive, between Cedar Hill Golf course and Cedar Hill Road for 22 years. I have seen a common wall lizard once, in late spring of 2020 at our address. I knew through my work with invasive species that this was the invasive lizard that is prolific on Vancouver Island. I was surprised by its appearance at our house and this first record for our neighbourhood. We dispatched the lizard once confident it was not the native Northern Alligator Lizard (Elgaria coerulea). My dad suggested that the lizard was accidentally transported in a trailer of soil recently purchased from Stanhope farm in Central Saanich (near Tanner Road x Patricia Bay Highway).

I consulted iNaturalist to find observations in my neighbourhood and Stanhope farm for that time frame. The nearest reports of common wall lizards my residence were recorded June 2020, 380m and 960m from my address (straight line distance). Less than 100m from Stanhope farm there was a research grade observation of a common wall lizard made in September 2019 (Silverman, 2019). My observation is aligned with the thought that common wall lizards dispersed through accidental transportation (ISCBC 2020; Engelstoft et al., 2020; Long, 2020).

Connections: The Local and the Global

After identifying this as a curious event I’d like to investigate, I found Dr. Gavin Hanke’s webinar with the Invasive Species Council of BC (ISCBC) from 2020 discussing the common wall lizard invasion in British Columbia. He explains that while common wall lizards were released in 1967, 1970, and 1986 in the greater Victoria area, it was not until after 2004 that seemed to become more abundant (Government of BC, n.d.; ISCBC, 2020; Engelstoft et al., 2020; Long, 2020). Research conducted in 1991 at the site of the original release found limited dispersal (1.4km) over two decades (Allan et al., 1993). Dr. Hanke attributes this post 2004 boom in dispersal and abundance to accidental transportation (populations got to a size where accidental transport became likely) and species characteristics that enable them to thrive (aggressive, 40-100m range dispersal, survival in urban/disturbed habitat, reproduce rapidly, dietary generalists, and native climate similar) (ISCBC, 2020; Long, 2020). Invasive species are not just a local issue to southern Vancouver Island. Invasive species are one of the leading threats to global biodiversity and the rate introductions is alarming and accelerating globally (Armenteras et al., 2019 p.142 and 150; Farley and Voinov, 2016 p.390; IPBES, 2019 p.13). Further, the invasion of the common wall lizard here is not an isolated event, there are other places where they have invaded, such as Cincinnati in Ohio and Southern England as noted in Allan et al. (1993) and by Dr. Hanke (ISCBC, 2020). A North American iNaturalist project has been created for tracking common wall lizards (Engelstoft, 2018). The failure to act quickly to detect, eradicate, and control invasives often is followed by exorbitant costs and environmental impacts (Armenteras et al., 2019 p.143). The local example of the common wall lizards’ delayed ‘invasion’ after introduction is a cautionary tale where an exotic species reaches the tipping point, and becomes invasive.

References Allan, M., Gregory, P. T., & Prelypchan, C. J. (1993). The ecology of introduced Common Wall Lizard (Podarcis muralis) in Saanich, Vancouver Island. BC Ministry of Environment. https://a100.gov.bc.ca/pub/eirs/finishDownloadDocument.do;jsessionid=284E41283964807DB1129E0C83E74D28?subdocumentId=7621 Armenteras, D., Hills, J., McRae, L., & Zastavniouk, C. (2019). Chapter 6 Biodiversity. In Global Environmental Outlook 6 (pp. 141–173). UN Environment Programme. https://www.unep.org/resources/global-environment-outlook-6 Engelstoft, C. (2018, December 14). Common Wall Lizard Spread in North America Project. iNaturalist Canada. https://inaturalist.ca/observations?nelat=63.00953953466313&nelng=9.792534347720032&place_id=any&project_id=31368&subview=map&swlat=-14.744248219670967&swlng=160.96440934772005 Engelstoft, C., Robinson, J., Fraser, D., and Hanke, G. (2020). Recent Rapid Expansion of Common Wall Lizards (Podarcis muralis) in British Columbia, Canada. Northwestern Naturalist, 101: 50-55. https://bcreptilesandamphibians.trubox.ca/wp-content/uploads/sites/1420/2022/01/engelstoft-2020.pdf Government of BC. (n.d.). Invasive Species Alert!: Common/European Wall Lizard . Government of BC. https://www2.gov.bc.ca/assets/gov/environment/plants-animals-and-ecosystems/invasive-species/alerts/european_wall_lizard_alert.pdf
https://reader.elsevier.com/reader/sd/pii/S0301479716305023?token=9775BCB7C2BCCB90A9F1B9DA79602E5A35DBAC9BED679617BCFBC6E7CBBF37C29A8DDDE56F3FDFB246DD94FA5DD6554B&originRegion=us-east-1&originCreation=20220926054335 IPBES. (2019). Summary for policymakers of the global assessment report on biodiversity and ecosystem services of the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services. S. Díaz, et al (eds.). IPBES secretariat, Bonn, Germany. https://doi.org/10.5281/zenodo.3553579 ISCBC. (2020). Exotic reptiles in BC. YouTube. YouTube. https://www.youtube.com/watch?v=GilOvbcwZuc. Long, C. (2020). Lizards, Lizards Everywhere! CRD. https://www.crd.bc.ca/ Ministry of Forests. (2022, August 18). Invasive amphibians and reptiles. Province of British Columbia. https://www2.gov.bc.ca/gov/content/environment/plants-animals-ecosystems/invasive-species/priority-species/amphibians-reptiles Silverman. (2019, September 20). Common wall lizard (Podarcis muralis). iNaturalist Canada. https://inaturalist.ca/observations/33087927