February 6, 2011
Feral, Loose Dogs Threaten Wildlife
A biologist at Utah State University said in a newly published paper that man's best friend may be a formidable enemy to wildlife, pointing out the harmful effects loose dogs have on other animals.
Based on data from existing research and from their own case studies, Julie Young of Utah State and four other scientists concluded that feral and free-roaming canines may be responsible for wildlife woes, by hunting, harassing, or transmitting diseases to them.
While it is widely accepted that the introduction of non-native species can be harmful to natural ecosystems, dogs are not usually seen as invasive species.
"Dogs occur where humans occur, but we have tended to overlook their impact on wildlife mostly because we think of them as our companions," said Young, co-author of "Is Wildlife Going to the Dogs?," which is published in the journal BioScience.
Research in Idaho showed the presence of dogs had affected some deer populations, and in Colorado, a study showed that wildlife such as bobcats are avoiding trails where people often walk their pet dogs, Young cited.
Packs of feral dogs on the Navajo reservation in Arizona have chased livestock, decimating populations of smaller mammals such as rabbits. Feral dogs are also seen as a disease vector for rabies among people and other animals, said Young.
Loose dogs were also suspected as the main culprits in a distemper outbreak in northern Wyoming in the 1980s that was linked to the catastrophic deaths of endangered black-footed ferrets.
While studying three endangered species -- wild sheep, gazelles and antelopes -- in central Asia, Young said the issue of dogs affecting wildlife came to her attention. The steep rate of injury and death wildlife sustained from free-roaming dogs prompted Young and her team to take a closer look at the phenomenon on a global scale.
In doing so, they found that dogs, with an estimated worldwide population of 500 million, can cause more damage to wildlife, livestock and other animals than can wolves and other top predators.
Young cited one study that concluded, through genetic testing, that dogs -- not wolves -- were responsible for a flood of livestock killings in the mountainous Basque country between Spain and France. And investigators found that feral dogs were responsible for most of the domestic sheep kills in the French Pyrenees in the mid-1990s.
Despite leash laws in many countries and laws permitting prosecution of dog owners whose pets chase and kill wildlife, violators are rarely punished because enforcement agencies do not have the manpower and are under-funded to enforce such laws, Young said.
While many dog owners would not agree with the findings of the study, Young said there are low-cost, common-sense solutions to the problem. Public dog-training programs and vaccinations against rabies and distemper are good places to start for many dog owners.
"Some people might think it's cute to watch their dog flushing sage grouse (an imperiled bird in Western states) but the grouse might abandon its nest because of it," said Young. "It's better for people to make the change instead of having it imposed on them."
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