‘Man’s best friend’, or vicious invader?
Photo by Renzo Stanley (Flickr)
by Mairi-Netta Young
Having contributed to the extinction of nearly a dozen species – consisting mostly of birds - dogs have been named the third most significant human-induced predators after cats and rats. Scientists believe that dogs are threatening the existence of nearly 200 species worldwide – 30 of which are listed as critically endangered.
Despite this alarming evidence, very little conservation attention has been turned to this issue. Many dog owners are unaware of the impact their ‘harmless’ pet can have if allowed to wander freely in the wild.
A study, conducted in Chile, found that feral and free-ranging dogs have been documented predating and harassing the majority of large terrestrial mammals; this includes three species of canids (mammals from the dog family) and three species of deer.
And the problem continues to worsen. At current, it is estimated that there are one billion domestic dogs worldwide. The numbers of feral dogs, however, is not very well known. Head of an invasive species specialist unit at the IUCN, Piero Genovesi, suggested that as population increases, the number of dogs will also increase, making it “a matter of serious concern.”
Studies published in Biological Conservation have shown that countries with the highest number of feral dogs tend to have the highest number of species affected by their harassment – suggesting that the matter lies within the abandoning of domestic dogs. The areas found to be most affected are regions in Asia, Central and South America, the Caribbean and parts of Oceania.
So, why are dogs an issue?
It is said that dogs affect wildlife in five general ways; predation, ecosystem disturbance, disease transmission, competition for prey, and interbreeding with closely related species. Factors which have led to the extinction of at least eight species of bird, including the New Zealand quail.
Much of the evidence for such factors have come from social media; from photographic evidence of a snow leopard being hunting by three feral dogs in Tibet and polar bears being harassed by free-ranging dogs - to the viral footage of ‘Fenton’ chasing wild deer in England. Other evidence comes from rehabilitation centres such as in Chile, where 70% of pudu (the world’s tiniest deer) brought to the centre have been attacked by dogs.
Perhaps the most serious effect of dogs is their role in the spread of diseases to other species. Arnulf Koechncke, director of species conservation with WWF in Germany, says that rabies and canine distemper are the most notable examples, stating that “there have been repeated outbreaks of these disease among critically endangered Ethiopian wolves, for instance, as well as of rabies in India and Nepal.”
So, how to fix the problem?
For many decades, conservationists have battled with the idea of culling feral and free-ranging dogs in badly affected areas - a controversial issue that tends to generate vast opposition. As well as the public’s disagreement, many scientists also argue that a cull would be unsustainable. “Killing campaigns to reduce or eliminate dog populations is not only inhumane but ineffective, creating a population vacuum that is quickly filled by an influx of new dogs from other areas” says Kelly O’Meara of the Humane Society International. Believing instead, that “the key to addressing conflicts in an effective and sustainable way is to gradually reduce the dog population through humane dog management programmes, involving the spaying and neutering of dogs to curb the overall numbers, and then mass vaccination to ensure the population is healthy and disease free.” – an arguably vast and expensive task.
Conservations, however, remain uncertain that there is any suitable solution at current. And, until this solution is found, our ‘best friends’ will continue to threaten the world’s wildlife.
