Biol Invasions (2010) 12:3627–3636 DOI 10.1007/s10530-010-9755-2
ORIGINAL PAPER
The risk of zoological parks as potential pathways for the introduction of non-indigenous species Marı´a C. Fa`bregas • Federico Guille´n-Salazar Carlos Garce´s-Narro
•
Received: 10 November 2009 / Accepted: 29 March 2010 / Published online: 4 April 2010 Ó Springer Science+Business Media B.V. 2010
Abstract Zoological parks have been associated with an increasingly frequent origin for accidentally released animal species. Such species have become invasive in some cases. The goals of this study are to evaluate the risk of potential animal escape at zoological parks by assessing the security of animal enclosures, and to identify which factors could be affecting such security. We visited a random sample of 1,568 animal enclosures belonging to 63 Spanish zoological parks, and assessed their security with a defined criteria based on the suitability of the physical barrier of the enclosure and the impossibility for the public to release the animals. To our criteria, we found 221 enclosures which were non-secure against animal escape. Such enclosures were unevenly distributed among 47 zoological parks (74.60% of the sample), and housed non-indigenous species in 79.64% of the cases (21 species listed by the European Inventory of Invasive Species). Seven factors were analyzed to assess their effect on enclosure security. Six of them
M. C. Fa`bregas (&) F. Guille´n-Salazar Departamento de Fisiologı´a, Farmacologı´a y Toxicologı´a, Facultad de Ciencias de la Salud, Universidad Cardenal Herrera, 46113 Moncada (Valencia), Spain e-mail:
[email protected] C. Garce´s-Narro Departamento de Produccio´n Animal, Sanidad Animal y Ciencia y Tecnologı´a de los Alimentos, Facultad de Veterinaria, Universidad Cardenal Herrera, 46113 Moncada (Valencia), Spain
were found to have an effect, and three were selected by a logistic regression model as the main predictors for secure enclosures. Such factors are discussed, and measures are suggested to reduce the risk of zoological parks as a potential pathway for the introduction of non-indigenous species. Keywords Non-indigenous species Invasive alien species Zoological parks Introduction pathways Enclosure security Animal escapes
Introduction Biological invasions are a significant component of human caused global change (Vitousek et al. 1997). Over the past few centuries, non-indigenous species (hereafter NIS), defined as species or lower taxon introduced outside its natural past or present distribution (CBD-COP 2002), have caused untold damage to the human population, negatively affecting health (Bright 1998) and agriculture (Mack et al. 2000; Pimentel et al. 2000), as well as economy (Pimentel et al. 2001). According to the Convention on Biological Diversity, those NIS whose introduction and/or spread threaten biological diversity become invasive alien species or IAS (CBD-COP 2002). This phenomenon has been widely documented (Simberloff 1996; Parker et al. 1999) to the point of being recognized as the second major threat to global
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biodiversity, right after habitat loss and landscape fragmentation (Schmitz and Simberloff 1997; Walker and Steffen 1997; Macdonald and Thom 2001). This threat is the principle for the inclusion of biological invasions under ‘‘Threats to Biodiversity’’ in the framework of the Convention on Biological Diversity (BIP 2006). The goal of the Convention on Biological Diversity regarding biological invasions is to control threats from IAS through two specific targets: to prevent their introduction by controlling their routes of entry and to develop management plans for major NIS that threaten ecosystems, habitats or other species (UNEP 2004a, 2004b, 2005). Once a NIS is established, eradication is often impossible, and mitigation and control are difficult and expensive (Kolar and Lodge 2001). Therefore, a reduction in the introduction of NIS via routes of entry is the single most direct and potentially effective means of reducing the threat to biodiversity from IAS (Carlton and Ruiz 2005). Non-indigenous species can reach an ecosystem through a variety of pathways (DAISIE 2008). Escape from captivity (either for production or leisure purposes) is one of the most common ways of vertebrate introduction (Williamson 1996). In that regard, zoological parks seem to be more and more frequently the origin of accidentally released animals (Clergeau and Ye´sou 2006). These centers house great numbers of wildlife species in their facilities, and although some of them have native fauna in their collections, most animal species are not indigenous to the place where the zoological park is located, therefore becoming a potential source of NIS if animals escape (IUCN 2002a). In fact, animal escapes from zoological parks worldwide have been previously documented (Csurhes 2003; Jiguet et al. 2008), and some of these escaped species have become invasive (Roll et al. 2008; Clergeau and Ye´sou 2006; Jousson et al. 2000). In Europe, 82 non-indigenous terrestrial vertebrate species have been introduced as a consequence of escapes from zoological parks, becoming such centers the second most important known pathway for the introduction of NIS in this region (DAISIE 2008). Considering the importance of zoological parks as introduction pathways for NIS, our first goal is to evaluate the risk of potential animal escape at zoological parks by assessing the security of the enclosures housing the animal collection. Also, given that the security of an animal enclosure within a
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zoological park can be affected by several factors, including the nature of the species housed, the design of the enclosure assessed, or the management of the zoological park itself, our second goal is to determine which factors affect such security and propose measures to better address IAS within the zoo community.
Methods Data collection took place in Spain, where 63 out of the 83 existing zoological parks (defined as permanent establishments where animals of wild species are kept for exhibition to the public, with the exception of circuses and pet shops, hereafter ‘‘zoos’’) officially registered at the country in 2003, participated in the study (unpublished report of the Spanish Ministry for the Environment). These centers voluntarily agreed to participate in a broader study aimed at assessing the situation of Spanish zoos when the national legislation relating to the keeping of wild animals in zoos (Ley 31/2003) came into force due to the incorporation of the European Community Zoos Directive 99/22/EC into national legislation (Rodrı´guez-Guerra and Guille´n-Salazar 2006). The participating zoos filled out a comprehensive questionnaire that included, amongst other data, a complete list of the species and specimens which made up their zoological collections. The study sample comprised 1568 enclosures (Table 1); 1,469 enclosures to which the public had no access (i.e. the animals were observed from outside) and 99 enclosures where the public could access the exhibits, either in a vehicle or by foot (i.e. walk-in enclosures). We randomly chose 30 species from each participating zoo. When a zoo had less than 30 species, all the enclosures were evaluated. Prior to the selection process, the following domesticated species were excluded from the analysis: honey bee (Apis mellifera), mithan (Bos frontalis), yak (Bos grunniens), zebu (Bos indicus), Bali cattle (Bos javanicus), European cattle (Bos taurus), water buffalo (Bubalus bubalis), Bactrian camel (Camelus bactrianus), dromedary (Camelus dromedarius), dog (Canis familiaris), goat (Capra hircus), goldfish (Carassius auratus), Guinea pig (Cavia porcellus), pigeon (Columba livia), donkey (Equus asinus), horse (Equus caballus), cat (Felis catus), chicken (Gallus gallus), llama (Lama glama), alpaca (Lama
The risk of zoological parks Table 1 Security of enclosures by taxonomic classification of housed species
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Zoological group
Mammalia
Number of enclosures in the sample
Number of non-secure enclosures
Percentage of non-secure encl osures within the taxon
Number of species in non-secure enclosures
444
42
9.46
37
119
18
15.13
15
Primates
90
6
6.67
6
Rodentia
31
6
19.35
5
Carnivora
153
5
3.27
4
51
7
13.73
7
569
124
21.79
98
Anseriformes
96
46
47.92
33
Psittaciformes
158
23
14.56
20
Passeriformes Galliformes
41 61
11 6
26.83 9.84
10 6
Artiodactyla
Other Aves
Pelecaniformes
11
7
63.64
5
Other
202
31
15.35
24
Reptilia
219
36
16.44
30
Squamata
149
15
10.08
14
Testudines
53
18
33.96
13
Crocodylia
17
3
17.65
3
Amphibia
14
2
18.18
2
Anura
11
1
9.09
1
3
1
33.33
1
229
15
6.55
14
Caudata Fish Perciformes
128
7
5.47
7
Characiformes
17
0
0
0
Other
84
8
9.52
7
Invertebrates
93
2
2.22
2
Lepidoptera Actiniaria
32 3
1 1
2.15 33.33
1 1
Other Total
58
0
1,568
221
pacos), turkey (Meleagris gallopavo), house mouse (Mus musculus), helmeted guineafowl (Numida meleagris), rabbit (Oryctolagus cuniculus), sheep (Ovis aries), brown rat (Rattus norvegicus), and pig (Sus scrofa). As the evaluation of zoos as potential pathways for NIS was studied by assessing enclosure security against escape, free-flying birds or any other species which were not housed in an enclosure but wandered freely in the zoo were not considered in the study. The evaluation of the participating zoos, including the security of their enclosures, was carried out through the application of an evaluation guide
0
0 183
specifically developed for this task (Guille´n-Salazar 2003). A team of seven biologists and veterinarians with broad experience in the zoo profession and/or in zoo inspection processes participated in the design of the evaluation guide. This guide was based on the standards of modern zoo practice (DETR 2000) as well as on the accreditation systems of the American Association of Zoos and Aquariums and the European Association of Zoos and Aquaria. In order to assess enclosure security, two aspects of the enclosure were examined: (1) The existence of a complete, well maintained, and appropriate physical barrier to prevent the escape of the animals housed at the
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enclosure (including sewage lines, filtration systems and, in general, any opening or valve that could allow the escape of an animal or part of it such as eggs) and (2) The impossibility for the public to release the animals directly (i.e. capturing the animal and removing it from the enclosure) or indirectly (i.e. opening doors or windows not properly locked or supervised by the staff). For the purpose of this study an enclosure was considered ‘‘secure’’ only when both conditions were simultaneously met. Otherwise the enclosure was categorized as ‘‘non-secure’’. Data were collected by three evaluators between October 2003 and May 2004. They were previously trained by the research director on the application of the evaluation guide, and started the evaluations once the indexes of concordance (Martin and Bateson 1993) used to assure inter-observer reliability reached 95% amongst them. Visits to the participating zoos were arranged and performed together with the person in charge of each center, who provided any information requested by the evaluators. Each zoo was visited (and its enclosures assessed) by a single evaluator, who took photographs of each enclosure and performed the evaluation supported by a data sheet (‘‘Appendix 1’’). When a species was held in more than one enclosure in the same zoo, the enclosure with more specimens was selected for evaluation. After the visit, the evaluators and the research director met, to review and confirm the results. Once the enclosures were classified as secure and non-secure, seven variables were analyzed to assess their effect on the variable ‘‘enclosure security’’: (1) Taxonomic group of the species held: mammals, birds, reptiles, amphibians, fish and invertebrates; (2) Species hazardousness to people (defined as species capable of causing harm to their keepers or to the public due to their physical strength or specific weapons including poison and behavior; EAZA 2008): harmless versus hazardous species, according to the list of hazardous species of the European Association of Zoos and Aquaria (hereafter EAZA); (3) Species natural distribution: indigenous versus non-indigenous species (i.e. NIS) to the Spanish territory, according to the National Catalogue of Threatened Species (Spanish Ministry for the Environment 2003); (4) Species invasiveness: invasive (i.e. IAS) versus non-invasive species, according to the European Inventory of Invasive Species for the
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Spanish region (DAISIE 2008); (5) Enclosure accessibility: walk-in enclosures (i.e. where the public is allowed to enter the enclosure) versus enclosures observable from outside; (6) Existence of a qualified curator (i.e. a curator with at least a MSc in Biology) in charge of the zoological collection at the zoo where the evaluated enclosure belonged to: presence versus absence of a qualified curator in staff; (7) Membership of the center being evaluated to a professional association of zoos (in this case, Asociacio´n Ibe´rica de Zoos y Acuarios, hereafter AIZA): AIZA members versus non-AIZA members. Firstly, each of the explanatory variables was analyzed with a bivariate procedure (chi-squared test) to assess its effect on the dependent variable (i.e. enclosure security). Then all variables were analyzed together using a multivariate analysis (forward stepwise logistic regression model) to detect which of them better predicted enclosure security (secure/non-secure) while addressing interdependence relationships among the explanatory variables. The chi-squared based Hosmer and Lemeshow test was used to test the overall fit of the logistic model, and the Wald statistic to test the significance of individual logistic regression coefficients for each of the explanatory variables (Likelihood Ratio method). Statistical significance was set at a = 0.05 for all tests.
Results We found that 221 out of the 1,568 evaluated enclosures were non-secure so therefore the animals could possibly escape (14.09% of the total). Such enclosures were widely distributed among 47 out of the 63 participating zoos, revealing that 74.60% of the zoos in the sample had at least one non-secure enclosure in their facilities (Fig. 1). A deficiency in the suitability of the physical barrier was the main cause for lack of security, affecting 71% of the nonsecure enclosures (157 enclosures). Animal release by the public was possible in 44.30% of the 221 cases (98 enclosures), and in 15.38% of the cases (34 enclosures), lack of security was a combination of both aspects. Table 1 summarizes the results regarding taxonomic classification of the animals held at the evaluated enclosures. Our data indicated that over half of the non-secure enclosures housed birds
The risk of zoological parks
3631
40 Error bars: 95,00% CI
30
20
10
0 1-20%
21-40%
41-60%
61-80%
Fig. 1 Zoological parks classified by their percentage of nonsecure enclosures in the evaluated sample. The horizontal axis represents the percentage of non-secure enclosures in a zoological park. Numbers in the vertical axis stand for the frequency of zoological parks within each of the categories indicated in the horizontal axis
(56.11%), followed by mammals and then reptiles. Birds not only had the highest representation in the sample (36.28% of the evaluated enclosures held birds), but also were the zoological group with the highest proportion of non-secure enclosures (21.79% of the birds were held at non-secure enclosures). Pelecanifomes and Anseriformes were the taxonomic orders with highest proportion of non-secure enclosures (63.34 and 47.92% respectively). Non-secure enclosures held 183 different species (Table 1), 141 of these were NIS to the Spanish territory. As some species were housed in more than one zoo, the total number of non-secure enclosures housing NIS was higher (167 enclosures). Additionally, 21 enclosures were found to house species listed in the European Inventory of Alien Invasive Species (DAISIE 2008). The animals held at those 21 nonsecure enclosures belonged to 17 species, where ten of them were reported as established (i.e. the species has formed self-reproducing populations where introduced, DAISIE 2008) in some Spanish areas (Table 2), and three species (coypu, Myocastor coypus; sacred ibis, Threskiornis aethiopicus, and redeared slider, Trachemys scripta) were identified as IAS (DAISIE 2008). It is worth mentioning that although the sacred ibis was eradicated from the Spanish peninsula in 2001 (Clergeau and Ye´sou 2006), we found a non-secure enclosure housing this
species at one zoo located near the area where the species had once been eradicated. Six of the seven explanatory variables analyzed were found to have an effect on enclosure security. The distribution of secure and non-secure enclosures varied depending on the taxonomic group of the species under evaluation (v2 = 58.444, df = 5, P \ 0.0001). Likewise, enclosures housing hazardous species (v2 = 4.578, df = 1, P = 0.032), walk-in enclosures (v2 = 22.409, df = 1, P \ 0.0001), enclosures in zoos with a qualified curator in charge of the zoological collection (v2 = 7.596, df = 1, P = 0.006) and enclosures in zoos belonging to AIZA (v2 = 32.580, df = 1, P \ 0.0001) tended to be secure against animal escape. Additionally, the distribution of secure and non-secure enclosures was also significantly different for the variable ‘‘invasiveness of the species’’ (v2 = 5.360, df = 1, P = 0.021), but in this case the percentage of non-secure enclosures was higher when the enclosures held an IAS (22.10%) than when the species held was a noninvasive one (13.58%). The only variable that did not significantly affect enclosure security was the species natural distribution (indigenous vs. non-indigenous species or NIS) (v2 = 0.030, df = 1, P = 0.863). The model generated in the logistic regression procedure fitted the analyzed data (Hosmer and Lemeshow test: v2 = 16.731, df = 6, P = 0.019), selecting the species taxonomic group, enclosure accessibility, and membership to a professional association of zoos (i.e. AIZA) as the independent variables that better explained enclosure security (Table 3). Such variables predicted 86.60% of the cases correctly.
Discussion Reports of animals escaping from zoos have been previously documented worldwide (Csurhes 2003; Jiguet et al. 2008). The data presented here relates to the risk of potential escape of zoo animals due to lack of security at their enclosures, instead of examples about actual escapes. We found that 14% of the evaluated enclosures were non-secure against animal escape, either due to problems associated with the physical barrier surrounding the enclosure and/or the possibility of the public to release the animals. Given that 75% of all the Spanish zoos participated in the
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Table 2 Species listed in the alien invasive species European inventory for the Spanish region (DAISIE 2008) and housed at nonsecure enclosures Alien species
Number of non-secure enclosures
Colonization status in Spanish Peninsula
Colonization status in Balearic Islands
Colonization status in Canary Islands
Invasive
1
Established
Absent
Absent
Yes
Agapornis personatus
1
Established
Not established
Not established
No
Alopochen aegyptiacus
1
Not established
Not established
Absent
No
Amazona aestiva Aratinga acuticaudata
1 1
Not established Established
Not established Absent
Absent Absent
No No
Cygnus atratus
2
Not established
Not established
Absent
No
Lamprotornis purpureus
1
Absent
Absent
Not established
No
Nandayus nenday
1
Not established
Absent
Established
No
Pavo cristatus
1
Absent
Absent
Not established
No
Phasianus colchicus
1
Established
Absent
Absent
No
Poicephalus senegalus
1
Not established
Not established
Established
No
Streptopelia roseogrisea
1
Established
Absent
Established
No
Threskiornis aethiopicus
1
Extinct
Absent
Not established
Yes
Elaphe guttata
1
Not established
Absent
Not established
No
Iguana iguana
2
Not established
Absent
Established
No
Testudo graeca
1
Absent
Established
Not established
No
Trachemys scripta
3
Established
Established
Established
Yes
Mammalia Myocastor coypus Aves
Reptilia
Total
21
Colonization status: Extinct (Once established, now extinct); Not established (the species has not formed self-reproducing populations); Established (the species has formed self-reproducing populations where introduced); Absent (no records of presence of the species for that region). (DAISIE 2008)
study, we consider that our results reflect quite accurately the situation in Spain. As our results correspond to a sample, and free-flying birds were not analyzed in our study (but comprise part of some zoological collections), the actual number of enclosures from which animals could potentially escape could reach near one thousand. This is the first time (to our knowledge) that the risk of escape from zoo enclosures has been evaluated. Similar analyses in other regions would help to address the importance of zoos as potential pathways for the introduction of NIS, especially considering that in Europe alone, 82 non-indigenous terrestrial vertebrate species have been introduced as a consequence of escapes from zoos (DAISIE 2008). Preventing the introduction of NIS has been regarded as the most direct and potentially effective means to reduce the threat to biodiversity from IAS
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(Carlton and Ruiz 2005). However, not all the species liable to escape represent an actual threat to the ecosystem. First of all, as a general trend most organisms die in transit or soon after release (Lodge 1993). Moreover, in the particular case of escapes, the success of any given animal in completely achieving freedom (other than chance) depends on its particular physical features and behavior. We would expect large body-sized species less capable of succeeding at their escape than small ones, as the former are more conspicuous to people. In the same way, hazardous species are probably less capable to reach the wild due to the imminent hazard they represent to the general public. Locomotion patterns also play an important role in the escape, both in terms of speed and fashion; those animals able to fly are more prone to succeed in their escape, simply because they become harder to catch successfully.
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Table 3 The relative importance of the independent variables on enclosure security in the forward stepwise logistic regression model. Likelihood ratio test was used for significance Variables in the equation
Walda
df
P-value
AIZA membership
25.432
1
\0.001
Taxonomic group
59.672
5
\0.001
Enclosure accessibility
35.606
1
\0.001
Constant
24.727
1
\0.001
Variables not in the equation
Score
Species hazardousness
2.254
b
df
P-value
1
0.133
Species natural distribution
.625
1
0.429
Species invasiveness
.307
1
0.580
Qualified curator in staff
.015
1
0.903
a
Wald statistic
b
Rao’s efficient score
Unfortunately, over half of the non-secure enclosures in the sample held birds, most of them NIS to the Spanish territory. Thirteen of those non-secure enclosures held bird species listed by the European Inventory of Alien Invasive Species, one of them (Threskiornis aethiopicus) already invasive (DAISIE 2008). The fact that birds are the zoological group with more enclosures with potential risk of escape is a reason for concern as many species within this group have all the characteristics mentioned above. Therefore, special attention should be paid to those enclosures holding species that are capable of flying, harmless to the public (especially if they are apparently naı¨ve, like former pet species), are small sized, or satisfy all the criteria discussed above. Although IAS are acknowledged as a threat to biodiversity by the mission statements and codes of practice of the zoo community (AIZA 2008; EAZA 2001, 2008; IUCN 2002b; WAZA 2005), according to our results, the potential environmental risk posed by NIS or IAS is not reflected in the security of their enclosures. The fact that most IAS are not directly harmful to humans could explain this lack of security. Our data seem to support such an idea, as none of the non-secure enclosures housing NIS (listed by the European Inventory of Invasive Species, DAISIE 2008) were hazardous to humans. Furthermore, none of the species (other than a few jellyfishes) listed in ‘‘the 100 worst invasive species for Europe’’ (DAISIE 2008) are directly hazardous to humans. In this sense, some NIS that have succeeded in invading new
ecosystems were former pets once released or escaped into the wild (e.g. green iguanas, Iguana iguana or red-eared sliders, Trachemys scripta). Considering that these species are quite frequent in zoos, they represent an excellent opportunity to raise awareness among the visiting public about the ecological harm associated with the release of nonindigenous fauna into the wild. Zoos belonging to a professional association (i.e. AIZA in the case of Spain) were found to have less non-secure enclosures than non-members. This could be explained by several factors. Firstly, professional associations are strongly committed to global conservation as stated in the Zoo and Aquaria Conservation Strategy (WAZA 2005). In fact, the Strategy specifically acknowledges the problem of biological invasions by stating that zoos ‘‘should ensure that exotic (i.e. non-indigenous) animals in their care do not escape and do not pose a risk to indigenous species’’ (WAZA 2005). Another important factor is qualifying for membership of professional associations. In order to qualify zoos are evaluated on a comprehensive set of aspects, including security of the enclosures to prevent animal escape, where the suitability of the physical barrier (in terms of the design and the construction materials) as well as its maintenance are assessed. However, as we detected non-secure enclosures at AIZA zoos, establishing stricter accreditation processes in the future could probably reduce the number of non-secure enclosures, and therefore the potential risk of zoos as introduction routes for NIS. In this regard, the existence of a legal framework within the European Union that requires governments and/or local authorities of all Member States to carry out inspection and authorization processes of existing and new zoos, also represents a powerful way to improve zoo security. Management perspective and future directions Non-indigenous species are a global concern and their control should be promoted internationally (Mooney 1999). Although our study sample was limited to Spain, a similar situation might be occurring in other European countries, as well as in other regions worldwide. We consider that enclosure security in zoos should be taken more seriously as these centers (as shown in our results) are a potential pathway for
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the introduction of NIS. 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. Governmental agencies and departments in those countries which already consider IAS in their legal frameworks and policies should accurately address enclosure security in their official inspections and authorization processes. As for those countries which still lack specific legislation regarding maintenance of NIS or IAS in zoos, it is now an urgent issue that policymakers take action as preventing the introduction of NIS is the most effective (and less expensive) measure to protect ecosystems against biological invasions. Acknowledgments We thank the Spanish Ministry for the Environment for funding the broader study that generated the data we used in this paper. We also want to thank the participating zoos for their assistance during this study. The manuscript greatly benefited from comments from Dr. V. Rodilla (Universidad Cardenal Herrera, Spain) and Dr. S. Sa´nchez-Pen˜a (Universidad Auto´noma Agraria Antonio Narro, Me´xico), as well as from those made by two anonymous referees.
Appendix 1 Questions regarding the security of the enclosures against animal escape included in the data sheets used by the evaluators when assessing enclosure security (from Guille´n-Salazar 2003). For the purpose of this study an enclosure was considered ‘‘secure’’ only when both conditions were simultaneously met. Otherwise the enclosure was categorized as ‘‘non-secure’’. Condition 1 The enclosure has a complete, well maintained, and appropriate physical barrier to prevent the escape of the animals housed within (including sewage lines, filtration systems and, in general, any opening or valve that could allow the escape of an animal or part of it such as eggs). Each of the following questions should be answered negatively to meet this condition.
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a. b.
c. d. e.
f.
g.
Could the barrier be knocked down by the animals held in the enclosure? Could the animals exit the enclosure by leaping or climbing the barrier (including the use of vegetation, tools, etc.)? Could the animals escape by digging under the barrier? Could the animals go through the barrier (especially young individuals)? Are there any pipes or ducts (sewage lines, water channels, etc.) in the enclosure that could allow the escape of the animals held in it? In the case of being a drive through or walk through enclosure, a double gate entry and exit system should be in place with sufficient space to allow the gates to be securely closed at the front and rear of any vehicle (or person) which may enter or need to enter the enclosure. Could the animals held inside exit the enclosure through any of the gates? Could the integrity of the barrier be compromised by any external factor (e.g. a fallen tree on the barrier)?
Condition 2 The public cannot release the animals held at the enclosure directly or indirectly. Each of the following questions should be answered negatively to meet this condition. a.
Could the public capture the animals and remove them from the enclosure? b. Are there any doors or windows that could be opened by the public due to lack of continuous supervision by zoo personnel and/or because they are not properly locked? c. Are there any objects surrounding the enclosure such as rocks, branches or forgotten tools that could be used to free the animals held at the enclosure (e.g. by tearing down the fences comprising the physical barrier of the enclosure)? Note: Violations with premeditation, planning and preparation that could be considered as an offense are not considered.
References AIZA (Asociacio´n Ibe´rica de Zoos y Acuarios) (2008) Estatutos de la Asociacio´n. Available from: http://www.aiza. org.es/pdf/politica/estatutos_es.pdf Accessed 26 Feb 2009
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