Letting the cat out violates European nature protection rules: Tilburg Univ. professors

Allowing cats to roam outside without human supervision is illegal according to European rules for nature protection, lawyers and Tilburg University researchers Arie Trouwborst and Han Somsen conclude. The domestic cat is a danger to nearly 370 endangered species and is considered one of Europe's top three most harmful exotic animals. The domestic cat is originally from Africa, Trouw reports based on interviews with Trouwborst, an associate professor, and Somsen, a full professor at the Tilburg Law School.

In the Netherlands alone, an estimated 140 million animals are killed by cats each year. The Netherlands counts between 2 and 3 million pet cats and tens of thousands of strays. Among the victims are birds, small mammals, reptiles, fish and amphibians. 

Even without hunting, cats can damage other species' populations. The mere presence of a cat can cause so much stress to birds that they breed less or feed their young less, according to the newspaper. Roaming domestic cats sometimes also breed with wild cats, resulting in the latter type occurring less and less. 

This is not only harmful to biodiversity, it is also illegal, according to the two legal scientists. Under the European Birds and Habitats Directive, the Netherlands is obliged to protect certain species and their habitats, and to limit potential threats. Allowing cats to roam around without supervision violates that directive, the lawyers argue 

"Even if it is not your intention to harm wild animals when you leave the cat flap open, that is what happens on a large scale", Somsen said. Trouwhorst added: "Every other pet does not go outside without an owner, from dogs to snakes. The exceptional position of the cat is actually very crazy." 

According to Trouwhorst, cats can get enough exercise in a well-sealed garden or on a leash, like dogs. "In busy cities with a lot of traffic, cats are often kept indoors for their own safety, and that works out fine." It will take some getting used to for cats and their owners, but measures are inevitable, the lawyers believe. "The damage caused by the cat is too great to remain an exception to the law."