Pet problems: Biological and economic factors that influence the release of alien reptiles and amphibians by pet owners

The trade of non-native animals as pets the main pathway for new invasive species if they become released into the wild. Here, we examined the trade in non-native reptiles and amphibians as pets in the United States. We found c. 1,700 species traded in the past two decades of which 126 species have been recorded as released in the wild. Using machine learning models, we show that larger-bodied, longer-lived species, who sold for cheaper prices were more likely to have been released. We propose policies and education focused on species with these characteristics in order to curb the impacts of new invasive species that originated as pets.

By Oliver C. Stringham & Julie L. Lockwood in Research

June 24, 2018


The number of alien reptiles and amphibians introduced and established worldwide has increased over the last decades. The legal pet trade is now the dominant pathway by which individuals of these species arrive in their non‐native locale. Despite its importance, specific factors of pet trade pathway that influence the release (introduction) of exotic reptiles and amphibians have not yet been examined. We set out to identify broadscale and easily measured biological and economic factors that influence the release of these exotic pets by their owners. We hypothesize that biological factors reflect the cost of care, and economic factors reflect the value that owners place on their pet, both of which can influence the probability when a pet is released. We collected life history and economic data on the 1,722 species of reptiles and amphibians sold within the US as pets over the last 18 years. We also compiled a list of pet trade‐attributed releases in the US (i.e., all free‐living species regardless of whether they successfully established). We used boosted regression trees to correlate species release status with their life‐history traits and economic attributes (r2 = 0.51, AUC = 0.89). We found that species with a high probability of being released were imported at higher quantities over our period of record, have a relatively large adult mass and commanded cheaper retail prices. The number imported and price interacted with longevity and adult mass to produce nonlinear increases in release probability. The most important interaction revealed that large‐bodied species imported in high quantities have a three times higher release probability compared to large‐bodied species imported in lower quantities. Policy implications: Our results provide guidance towards targeting exotic pet reptile and amphibian species that are at a high risk of being released. Species that are both prevalent in the pet trade and large‐bodied or long‐lived have the highest probability of being released. This will aid in developing education and policy solutions aimed at decreasing the rate at which these pets are released, thus curtailing the invasion process before these species can establish and impacts can occur.

Posted on:
June 24, 2018
2 minute read, 345 words
conservation invasive species wildlife trade exotic pet trade
See Also:
Response to the Department of Agriculture, Water and the Environment's 'Proposed amendments to the Appendices of CITES for Australian Native Reptiles'
Challenges and perspectives on tackling illegal or unsustainable wildlife trade
Scientists' warning to humanity on illegal or unsustainable wildlife trade