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Study Describes Another Problem With Zoos

An Environmental Risk Usually Ignored Is Identified

Published 01/25/10
By Barry Kent MacKay, Senior Program Associate

Some recently published research indicates that 75 percent of the zoos in Spain are at risk of having their animals escape, due to inadequate caging or barriers. The study was published in the scientific journal Biological Invasions, and divided the risk between those exhibits with inadequate containment and those where animals could escape “because the public could release them or remove them from their cages or tanks.” The concern of lead researcher Maria C. Fabregas and her team was specifically for the environment and conservation.

A male ruddy duck (Painting by Barry Kent MacKay)

There’s good reason for such concern in Spain. It was 60-some years ago that an American species of bird, the ruddy duck, escaped from captivity in Britain. For years it occurred as a harmless oddity, but in 1983 birds directly descended from those English escapees showed up in Spain, where there is an endangered species called the white-headed duck. Ruddy ducks began breeding with the white-headed ducks, producing fertile offspring. This process is called “genetic swamping” and the concern is that it could lead to the elimination of the white-headed duck, a species that also occurs, in small, discreetly isolated populations, in the Middle East. If the ruddy duck reaches those populations, there will be neither the means nor the will to protect the white-headed ducks.

A white-headed duck (Painting by Barry Kent MacKay)

It’s a grim choice. Risk the extermination of the white-headed duck, or keep killing ruddy ducks. Neither option sits well with those who care about animals and the environment.

There are a great many examples of both deliberate and unintended introductions of exotic, non-native species into the environment. Most people are aware, for example, of the damage to the environment done by cane toads, camels and rabbits in Australia (although many hypocritically ignore similar damage done by various livestock species such as sheep and cattle), but have we learned our lesson?

Not at all. One of Born Free USA’s campaigns is to have passed into federal legislation a bill, the Captive Primate Safety Act, designed to prevent the import of exotic animal species likely to cause environmental problems if they get loose. It’s an uphill battle against various special-interest groups who prefer to put native species at risk.

Originally, many non-native animals, such as foxes in New Zealand, mongooses in Jamaica and starlings in America, were put there by European settlers who wanted to bring familiar species to their new homes. Many species were moved around to placate hunters and anglers, with some streams in the United States now harboring as many non-native as native species, to the detriment of the latter. The fur and the exotic pet industries have both been responsible for many introductions. Visit London or many other European capitals and you may be surprised to see jade-green parakeets flocking by. These are rose-ringed parakeets originally from tropical and subtropical Asia. Might they harm, displace or endanger rare native species? It’s too soon to know, but there is a lot of concern.

Zoos as a source of such “alien” species have largely been overlooked, with poorly funded roadside and small private zoos posing the most serious risk. Concerns for public safety sometimes lead to animals who are potentially dangerous to the public being securely held, but there is no similar concern for those who pose a potential environmental risk should they escape. When Hurricane Andrew slammed into southern Florida in 1992, among other things it caused about half a dozen purple swamphens to get loose. Others escaped from private collections. The species is now well-established in the wild, and although no specific damage has been caused nor any species put at risk, thousands have been “removed” by wildlife managers, simply as a precautionary measure.

In preference to causing such problems, or being faced with their bloody solutions, it is better to prevent the impact of alien species occurring in the first place. At the very least zoo enclosures should be secure — as they are required to be by law throughout the European Union. In Florida alone there are an estimated 200 exotic species in the wild, of which some, such as boa constrictors in the Everglades, are both well established and causing ecological problems, resulting in orders from the state that they be killed on sight.

Prevention of such disasters should be the legislated mandate of every zoo, private or public. As Fabregas said, invasive species “… are one of the leading causes of biodiversity loss, 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.”

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