T

wo of the processes most threatening biodiver-

sity – the illegal wildlife trade and the intro-

duction of alien species – can intersect with

potentially negative effects. Our investigation

of illegal reptile-keeping in Victoria found that

12 of the 28 reptiles known to be kept illegally could become

established and form self-sustaining breeding populations in

the wild.

Moreover, our research indicates that the keeping of illegal

reptiles in Victoria is not only a likely environmental issue but

also a potential human health hazard. Of the 28 illegal reptiles

reported in our study, ten of them are highly venomous snakes

that aren’t native to the country.

The Risk Posed by Illegally Kept Reptiles

There is a blanket ban on importing and keeping alien reptiles

in Australia. This may have the unintended consequence of

fostering the illegal trade in reptiles, as species that are rarely avail-

able may become more sought-after by wildlife enthusiasts.

Victorian authorities have been conducting a long-running

campaign to seize illegal species within the state. Strategies have

included an amnesty for people to relinquish alien species, and

active policing efforts to seize illegally kept reptiles.

Our investigation gathered information about alien reptile

species reported in the state during the period 1999–2012, and

this gave us an insightful snapshot of the diversity of alien

reptiles present within the borders of the state. We then used

this information to evaluate the risks posed by illegal reptile-

keeping in Victoria.

The first step in our research was to understand historical

patterns of reptile establishment success in mainland Australia

and the island territories of Christmas Island, the Cocos

(Keeling) Islands and Lord Howe Island over the period 1840–

2005. We asked:

• which alien reptile species have been introduced in the past
  (i.e. ever been found in the wild in Australia)?


• of those introduced, which ones are established in Australia?


• are there any differences between the species that were
  successful and those that failed to establish?
  Comparing the features of failed and successful alien reptiles
  through a statistical model provided insights into the factors
  determining the establishment success of alien reptiles in
  Australia. Our results revealed that successful alien reptiles
  were smaller in body length and were released or escaped a
  higher number of times into the wild than their failed counter -
  parts. Both factors have influenced the establishment success
  of alien reptiles in other parts of the world.
  Once we had constructed a model for predicting the estab-
  lishment success of alien reptiles in Australia, we proceeded to
  estimate the risk of establishment of the 28 illegally kept reptile
  species in Victoria.
  We used a statistical
  model based on
  historical species
  introductions to
  predict what will
  happen if the illegally
  kept reptiles are
  released in mainland
  Australia.
  Our findings indi-
  cated that the prob-
  ability of illegal

36 ||MAY/JUNE 2017

The Illegal Wildlife Trade as a

Source of New Alien Species

PABLO GARCÍA DÍAZ, JOSHUA ROSS, ANDREW WOOLNOUGH & PHILL CASSEY

The illegal wildlife trade is increasing the likelihood that foreign reptiles will become

established in the wild – with consequences for both biodiversity and human health.

Yellow anacondas (Eunectes notaeus)

have been illegally kept in Victoria

despite being one of the most likely

alien reptiles to become established

in the wild. Bernard Dupont CC CC-by-2.0