Why People Release Their Exotic Companions
Invasive reptiles and amphibians can impose severe ecological and socio-economic damage, sometimes even driving native species towards extinction. Although individuals sold as exotic companion animals are never intended to be let loose, the observed presence of such traded species in nature suggests that a portion do end up being released. In fact, the exotic animal trade has become the main source of alien reptile and amphibian species’ introductions worldwide.
Companion animal release events are already known to be geographically localized and proportional to the number of people living with exotic animals in a given area. In order to help to guide efforts aimed at curbing companion animal releases, researchers in the United States studied how various biological traits and economic factors influence release outcomes. The researchers combined exotic animal market data with detailed records of reptile and amphibian releases within the US.; 1,722 species were identified as being traded in the U.S., with lizards and snakes being the most sold animal groups – 739 and 490 species, respectively.
The following parameters were hypothesized to have an effect on predicted release:
- Level of care – the probability of release increasing when there is a mismatch between the perceived and actual level of care needed to maintain the animals:
- Adult Size – although smaller-bodied animals may be more likely to be released accidentally, larger species tend to be released more often due to them outgrowing their housing.
- Longevity – long lived species are at a higher risk of being released.
- Offspring – species producing many young may be released more often.
- Economic factors – keepers may place less value on low-cost companion animals and therefore be more likely to release them when care becomes costly or inconvenient:
- Market Abundance – less-rare animals are more likely to be released.
- Market Price – exotic animals traded at lower prices are at a higher risk for release.
- Time On Market – the longer animals are being traded, the more releases occur.
The findings confirm that the quantity of animals imported, price, and adult mass had the largest effects on release probability. Meanwhile, longevity, reproductive output, and time on market had positive relationships with release probability, albeit less significant ones. The most notable confounding factors were large-bodied species imported in high quantities, who had a threefold higher release probability compared to the same species imported in lower quantities.
All in all, the results indicate that there are biological and economic factors that clearly increase the probability of exotic reptiles and amphibians being released in the U.S. Interestingly, although larger-bodied reptiles and amphibians are more likely to be released, other research suggests that smaller species are more likely to establish self-sustaining populations. Similarly, despite import quantity strongly increasing release probability, this does not translate directly into higher probability of successful establishment.
The knowledge gained from the study could allow for the development of effective policy and education tools that could decrease the prevalence of certain exotic animals (i.e. those with high release probability) on the market, or to encourage guardians to responsibly dispose of unwanted companion animals, for example via “buy-backs” or “amnesty events.” Effective approaches could include warning consumers about the zoonotic risks of exotic animals. Similarly, the authors propose that available resources and information should also include how the animal’s adult size and longevity increase care requirements. Animal advocates will appreciate these findings, especially having in mind the recent efforts in the field of invasion risk assessment.