New research on zoos in Spain found that 75 percent of them are at risk of their animals escaping.
The study, published in the journal Biological Invasions, determined that 71 percent of that overall figure referred to animals that could escape due to insecure housing by getting through or over the physical barrier around their enclosure.
The rest could get out "because the public could release them or remove them from their cages or tanks," according to María C. Fàbregas, lead author of the study and a researcher at the Ethology and Animal Welfare Unit of Cardenal-Herrera University (UCH) in Valencia.
For the study, she and her team examined 1,568 animal houses in 63 Spanish zoos. Birds are the animals most likely to escape, but lions, bears, monkeys, crocodiles and other more toothy animals are also on exhibit at these zoos.
Birds turn out to pose the greatest threat. It's not a Hitchcock "Birds" thing. Instead, it has to do with exotic species escaping and taking over the ecological niches of native birds.
"As zoos house a large number of exotic (non-indigenous) species, they could become an entry channel for these species if they escape, with the potential environmental risk that this implies", Fàbregas told Plataforma SINC.
"Species that could pose a danger to public health are usually housed in secure accommodations. But those that could represent a danger to the environment if they escaped (invasive species) tend to be in insecure housing," points out Fàbregas, who added that birds are more likely to be in such housing.
This latest study was part of an overall effort by the Ministry of the Environment, Rural and Marine Affairs (MARM) in Spain to create the first inventory of zoos and aquariums in the country.
"Of the 1,568 animal houses studied, 221 were insecure against the threat of the species housed in them escaping, 167 housed non-indigenous species (potentially dangerous to the environment), and of these 21 housed invasive species," Fàbregas and her team wrote in the paper.
"(I)nvasive species are one of the leading causes of biodiversity loss," she continued, "but they can also have negative effects on human health, agriculture and the economy. Controlling their entry routes is the most effective way of tackling this threat."
Some of these potentially harmful animals do not pose a direct physical threat to people, and they may even be coveted as attractive, exotic pets. For example, pets like the red-eared slider turtle (Trachemys scripta), green iguanas (Iguana iguana), parrots, and even parakeets can hurt local ecosystems if they escape, according to the scientists.
The team says that zoos, already recognized as a source of invasive species, should adopt "all the measures available to them to prevent their animals from escaping. Preventing non-indigenous species from entering the environment is the best way of tackling the problem of biological invasions."
The researchers recommend that animals not be allowed to walk freely within zoo grounds. They also call for physical barriers marking zoo boundaries to prevent individuals from escaping through drains, sewers or any other channels.
One measure that is already common in some zoos is for them to have their own waste water treatment system, particularly at parks with aquariums or those near the coast. The goal is to prevent pathogens and parasites from getting out, as well as "any other potentially dangerous biological material (seeds, larvae, fragments of aquatic plants, etc.)," says Fàbregas.
Images: SINC
Tags: Amphibians and Reptiles, Animal Behavior, Animals, Human Behavior, Humans
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