Breaking out of the zoo: study finds high risk of species escape

Lax security at zoos is putting ecosystems at risk for invasion by exotic species according to a new study by researchers in Spain.

Marıa Fabregas and fellow study-authors evaluated 63 of the existing 83 zoological parks in the country. They found that 221 out of the 1,568 evaluated enclosures were not secure against animal escape.

Of these, 98 (48.3%) were deemed insecure because the public could release the animals directly.

Zoos already are the 2nd biggest contributor of exotic species invasions in Europe. At least, 82 non-native terrestrial vertebrate species have been introduced to the continent as a consequence of zoo escapes.

The study did not mention the specific species - though after searching, I found references to the sacred ibis as an example. 

The study found that non-secure enclosures held 183 different species - 141 of which are non-native to the Spanish region and 21 of which have been already listed in the European Inventory of Alien Invasive Species.

Birds were the most likely to be housed in non-secure enclosures. The researchers did not include free-flying birds in their analysis - so the risk estimates for species escape are probably conservative.

The study found more secure enclosures in zoos with qualified curators in charge of the collection and those that belonged to AIZA - the national zoological association.

This study will hopefully serve as a wake-up call for zoos in Europe and beyond. Zoos make an important contribution to species conservation - so my hope is that this negative study will turn into something positive.

The authors note that zoos could use their collection to educate people about the dangers of invasive species such as green iguanas and red sliders, which have established in the wild after being released by pet owners. 

In terms of making zoos more secure against escaping animals the authors write,

"From our point of view, the situation could be managed better by the zoo community itself through a specific set of measures, including more demanding accreditation processes by professional associations."

"Other strategies could include the identification and labelling of those species especially harmful for the environment, both to warn zoo personnel about the potential risk of NIS within their animal collection as well as raising awareness amongst the public about the risk of releasing NIS into the wild."

--by Rob Goldstein

Fàbregas, M., Guillén-Salazar, F., & Garcés-Narro, C. (2010). The risk of zoological parks as potential pathways for the introduction of non-indigenous species Biological Invasions DOI: 10.1007/s10530-010-9755-2