A new code for preventing animal escapes from zoos

Himalayan porcupines and Egyptian fruit bats do not belong to the European fauna, yet a few years ago they were well established in the wild, respectively in Devon (UK) and in the Canary islands. Wildlife managers decided to remove them to mitigate their impact on the new environment. Nevertheless, the problem could be easily prevented, because the introduction of the two species was probably a consequence of zoo escapes.

Specific and comprehensive analysis regarding invasive alien species (IAS) originated by escapes and/or releases from zoological gardens and aquaria in Europe are lacking, but there are evidences of some IAS populations still thriving and clearly originating from such pathways (even though in terms of relative risk, zoos and aquaria have a limited responsibility compared to other pathways i.e. pet trade, hunting, horticulture, etc.). A famous case is the one of the ruddy duck, a species of North American origin, which represents a major threat to the European white-headed duck, and is now being targeted by costly management programs. Another famous “escape” is the one of the tropical alga Caulerpa taxifolia unintentionally introduced from a public aquarium into the Mediterranean Sea. There is also an episode regarding the transmission of disease, like in the case of the deadly amphibian fungus Batrachochytrium dendrobatidis (Bd) accidentally introduced within the endangered population of the Mallorcan midwife toad (although before Bd was identified as a pathogen, and relevant screening methods were established). Surprisingly, there are also several records of marine mammals (including even beluga whales and sea lions) introduced from coastal dolphinaria and oceanaria, particularly in the Black Sea.

In Poland the Canada goose was unintentionally introduced also through escapes from a local zoo. Photo © Vibe Kjaedegaard

The identification of pathways and the implementation of best practices and voluntary measures to prevent the threats posed by IAS are currently recognised as critical issues in relation to the European policy on IAS. On the other hand, modern zoos are privileged allies of conservationists for the fundamental role they play on biodiversity conservation programs and related awareness raising activities (it is estimated that over 140 million people visit European zoos every year). For this reason, the Bern Convention and the Invasive Species Specialist Group (ISSG) of the IUCN, in collaboration with the European Association of Zoos and Aquaria (EAZA) have developed the European Code of Conduct for Zoological Gardens and Aquaria on Invasive Alien Species.

The publication in English (link updated on 27/11/2016)

The objective of this document is to provide guidance to zoological gardens and aquaria to strengthen their role for biodiversity conservation in Europe, by contributing to mitigate the problems related to the spread of IAS. This should be done through the following measures:

• Prevent the introduction and spread of IAS and related pathogens and diseases;
• Promote the need to raise awareness on biological invasions;
• Support IAS related research projects and other relevant conservation initiatives.

In line with the Convention on Biological Diversity (CBD) targets for 2020, as well as the EU biodiversity strategy to 2020, the code includes five main recommendations:

1. Adopt effective preventative measures to avoid unintentional introduction and spread of IAS;
2. Take into account the risks of IAS introductions in all wildlife and habitat management projects;
3. Proactively engage in awareness raising and outreach activities focusing on IAS and their impacts;
4. Adopt best practices for supporting early warning and rapid response system for IAS;
5. Be aware of all relevant regulations concerning zoological gardens and aquaria and IAS

The code - which includes a description of measure to implement the five recommendations above - has been formally approved at the last Standing Committee meeting of the Bern Convention on 30 November 2012. At the same meeting, with the aim of ensuring responsible and proactive policies and applying these in a coherent manner across Europe, the Standing Committee praised the innovative approach of such voluntary instrument, and adopted the Recommendation No.161 (2012). The aim is to invite all Bern Convention parties to implement the code, by drawing up their own national codes of conduct based on the European version, and by collaborating with zoological gardens and aquaria in implementing good practices aimed at preventing the spread of invasive alien species.

Another major achievement of the new code has been the formal acknowledgement received by the recent 11th Conference of the Parties of the CBD held at Hyderabad (India, 8-19 October 2012) which in its Decision XI/28. Invasive alien species:

“welcomes the development of voluntary codes of conduct on these separate pathways, such as the “Code of conduct on zoological gardens and aquaria and invasive species” developed by the Bern Convention, the IUCN Invasive Species Specialist Group and the European Association of Zoos and Aquaria, and requests the Executive Secretary to compile information and to work with experts to avoid and/or minimize the risks particular to these separate pathways”

Shutting the stable door before the horse bolts.
Drawing © Riccardo Scalera

Europe keeps investing in invasive alien species

Over 7 million euro are now available for projects aiming at increasing knowledge and understanding on biological invasions, as well as alien species impact in relation to both public perception and climate and other environmental changes. These are the themes specifically addressed by the new BiodivERsA 2012-2013 Pan-European call for research proposals specifically dedicated to "Invasive Species and Biological Invasions". The deadline for mandatory pre-registration is 14th of December 2012.

The European partners in the BiodivERsA network have already joined important efforts to organize and fund a pan-European call for research projects on invasive alien species (IAS) and biological invasions in the past. For example, within the 2008 joint call the BiodivERsA partners had funded the project RACE - Risk Assessment of Chytridiomycosis to European Amphibian Biodiversity. This project focuses on Chytridiomycosis, an amphibian disease responsible of causing die-offs and even extinctions of many amphibian populations around the world. The disease is caused by Batrachochytrium dendrobatidis (also called Bd for short), a fungus that for this reason is also considered one of the 100 World’s Worst Invasive Alien Species by the IUCN/SSC Invasive Species Specialist Group. In this context RACE aims at assessing the risk that Bd poses to European amphibians and at developing tools and protocols to enable surveillance of Bd across Europe. RACE also aims at improving the understanding where in situ mitigation and captive-breeding conservation efforts are most necessary to preserve European amphibian biodiversity. The findings should then be formalised into a European Threat Abatement Plan (ETAP).

African clawed frogs, a potential vector of Bd. Photo © Riccardo Scalera

Many research projects focusing on invasive alien species have been financed so far in Europe under the auspices of the various Framework Programmes (a scheme which also BiodivERsA belongs to). For example, according to the result of a specific study published on Biological Invasion journal, focusing on the period 1994-2006, the EC has funded a total of 90 research projects dealing with IAS, for a total budget of more than 88 million euro. Of these, 70 projects focused entirely on IAS and the other 20 had only a part of the activities related to this issue. That is a very important contribution to face the threat of biological invasions despite the lack of either a specific strategy or a dedicated financial instrument in the EU. Beside, this response complies with the priorities of the Sixth Environment Action Programme of the European Community for 2002-2012, and shows that concrete steps are being undertaken in the right direction to support the European Commission’s policy according to which IAS are recognised as a key pressure on biodiversity and a priority for action.

Short story of a pet turning into pest

Every year since 1928 a competition takes place in Angels Camp, California: the Jumping Frog Jubilee, a popular event inspired by Mark Twain’s famous short story The Celebrated Jumping Frog of Calaveras County. At the time - the story was first published in 1865 - the now endangered California red-legged frog (Rana aurora draytonii) was very common in that area: thus this was probably the species used for the competition and to which the story refers. However, at the end of the 19th century a new non-indigenous species entered the scene: the American bullfrog (Rana catesbeiana). Soon after being introduced into the area, the bullfrog replaced the indigenous red-legged frog within the Calaveras competition, and since 1986, thanks to Rosie the Ribiter and its jump over 6.5 m, the American bullfrog has held the world record!



Mark Twain portrait by Frederick Waddy

Nevertheless the greatest ultimate jump that the species managed to perform, with substantial help from human agency, has been through the Atlantic Ocean, from the New to the Old World. And it was definitely a very fortunate jump!

Like many other frogs, this typical edible species has experienced several introductions throughout the world for human consumption, often linked to the restaurant trade, but also for the pet trade. This “gourmet” indigenous to North America, was considered particularly suitable for aquaculture and has been frequently farmed for commercial production in countries outside its native range. The result is that the species is now spreading in several countries and islands worldwide, mainly as a consequence of escapes from breeding facilities (but also from garden ponds), or following intentional releases aimed at establishing wild populations to be regularly harvested. Thus, not surprisingly today the American bullfrog is thriving into many countries throughout the world, including several European countries (e.g. Belgium, France, Germany, Greece, Italy, the Netherlands, Spain, and U.K.).

The American bullfrog in Italy © Photo: Riccardo Scalera

Unfortunately, the species is also considered a serious ecological threat for indigenous species. Indeed it is a voracious opportunistic predator, eating a wide range of preys, from insects and other invertebrates to several vertebrates, including amphibians and reptiles, small mammals, and birds. Competition dynamics with indigenous species are also known to occur, as it may compete for food with indigenous amphibians, at either adult or larval stages. The American bullfrog may also bring the inherent risk of spreading harmful pathogens, like Chytridiomycosis. This fatal disease caused by the fungus Batrachochytrium dendrobatidis has been associated with a number of amphibian declines and extinctions in geographically disparate parts of the world.

In economic terms, although extensive studies on the impact of this species are not available, figures related to local situations show that their management may be very expensive. In the U.K., for instance, early efforts to remove the first breeding bullfrog population to protect native wildlife cost some 32 000 Euro. In Germany the annual cost for measures to control a few bullfrog populations (in only five ponds) was calculated to be 270 000 Euro, but the cost for control would rise to 4.4 billion Euro in the event that this species spreads throughout Germany.

Text excerpted from:

• Scalera R, 2007. An overview of the natural history of non indigenous amphibians and reptiles. In: Gherardi F. (editor) Biological Invaders in Inland Waters: Profiles, Distribution and Threats. Invading Nature: Springer Series in Invasion Ecology, Springer, Dordrecht, The Netherlands, Pp. 141–160.
• Scalera R, 2007. Virtues and shortcomings of EU legal provisions for managing NIS: Rana catesbeiana and Trachemys scripta elegans as case studies. In: Gherardi F. (editor) Biological Invaders in Inland Waters: Profiles, Distribution and Threats. Invading Nature: Springer Series in Invasion Ecology, Springer, Dordrecht, The Netherlands, Pp. 669–678.