Why are dogs allowed on hiking trails in national forests, but not in national parks? To state it more bluntly, why are the two federal government agencies at odds with each other? Either way, it’s a question that deserves an answer. The case for not allowing dogs on most backcountry trails in most national parks seems compelling, at least on the surface. Most parks publish their policies regarding pets on backcountry trails on their websites. Before digging deeper into this subject I assumed that these policies were developed by wildlife biologists, and were therefore backed by at least some science. But are these truly valid reasons? This blog post will attempt to answer that question.
Overall, the justifications for banning dogs on backcountry trails by the various national parks are fairly similar. Immediately below is a composite listing of these reasons from a sampling of park websites. The second section of this post cites data and research that support many of the claims by the National Park Service:
• Dogs may become prey for larger predators such as bears, mountain lions, wolves, coyotes, bobcats and even great horned owls. Moreover, if your dog disturbs and angers a bear or a moose, it may lead the angry bear or moose directly back to you. Wild canines are also highly territorial, especially during the summer denning season, and will kill loose dogs they encounter in their territory.
• Dogs can carry diseases into the park's wildlife populations. Conversely, they can also contract diseases from wildlife.
• Dogs are predators that can threaten, chase and even kill wildlife. They can also scare birds and other animals away from nesting, feeding and resting sites.
• The scent left behind by a dog can signal the presence of a predator, which disrupts or alters the behavior of park wildlife. Small animals may hide in their burrow the entire day after smelling a dog, and may not venture out to feed.
• Dogs can encounter insects that bite and transmit disease, or plants that are poisonous or full of painful thorns and burrs.
• Pets may dig or trample fragile vegetation, and pollute water sources.
• Dogs bark and disturb the quiet of the wilderness. Unfamiliar sights, sounds, and smells can disturb even the calmest, friendliest, and best-trained dog, causing them to behave unpredictably, bark excessively or even bite someone. Park visitors should be able to enjoy native wildlife in their natural environment without disruption from other visitors’ pets.
• Many people, especially children, are frightened by dogs, even small ones. Uncontrolled dogs can present a danger to other visitors.
As already mentioned, there are several published studies that support many of these assertions. The following are a few examples:
In 2008 the National Park Service published the results of a field research study, titled, “The Effects of Dogs on Wildlife Communities”, which discusses many of the points mentioned above in much more detail; in particular, how dogs impact wildlife. Conducted near Boulder, Colorado, the study found that the “presence of dogs correlated with altered patterns of habitat utilization for mule deer, small mammals, prairie dogs, and bobcats”. The assertion here is that dogs force animals to move away from trails, or force them to hide for extended periods of time. The paper also asserted that “Recreational trails with abundant dog scent could appear to carnivores to be linear dog territories, necessitating increased vigilance and activity”, meaning that the presence of dogs on trails is associated with increased activity of carnivores (bears, wolves, coyotes and mountain lions) in areas that are frequented by hikers.
A comparable study, conducted by Peter B. Banks and Jessica V. Bryant from the School of Biological, Earth and Environmental Sciences, University of New South Wales, Australia found that “dog walking in woodlands leads to a 35% reduction in bird diversity and 41% reduction in abundance, both in areas where dog walking is common and where dogs are prohibited.” This was also reported in Science News.
The Conversation (and Newsweek) by Dr. Al Glen from Landcare Research, New Zealand and Dr. Abi Vanak from the Ashoka Trust for Research in Ecology and the Environment, India, claims that “dogs are implicated in the extinction of at least 11 species”… and are “also a known or potential threat to 188 threatened species worldwide: 96 mammal, 78 bird, 22 reptile and three amphibian species. This includes 30 critically endangered species”, many as a result of predation, but also through disturbance and disease transmission.
A recent BBC article also asserts that dogs threaten almost 200 species worldwide (the article also includes a video of dogs harassing two bull elk).
The very first point in the list above states that dogs can become prey for predators such as bears, mountain lions, wolves and coyotes. Problems also arise for pet owners when a dog disturbs or angers a bear or a moose. These issues are also specifically addressed by scientific research. According to a study conducted by Stephen Herrero and Hank Hristienko, both leading authorities on bear behavior, dogs were involved in more than half of all black bear attacks on humans between 2010 and 2013. “The study found that in most of those cases, the dogs were running off leash and drew the bears to their owners.”
press release warning Coloradoans about the increase in moose encounters throughout the state. The release quoted District Wildlife Manager Elissa Slezak of Summit County, who stated that “moose react to dogs as they would to wolves - one of their primary predators. Moose will often attack even the most gentle dog as if it were a wolf, especially if the dog barks at or chases the moose. Unfortunately, the dog typically runs back to its owner bringing an angry, 1,000-pound moose back with it. The dog often gets away but the owner cannot escape and ends up injured instead. We've seen several instances where that exact scenario played out and the dog owner was seriously hurt."
In order to formulate the policies of the 17,000 acres of parks and natural areas managed by the City of Portland, Oregon, the Metro Government compiled and examined “54 peer-reviewed scientific journal articles and several research reports relating to the impacts of dogs in natural areas, including numerous literature reviews on the impacts of various types of recreation on wildlife and habitat”, which ultimately led to the banning of dogs on most trails within those spaces. What they found was categorized under four broad categories:
Physical and temporal displacement: “Displacement may be the most significant impact due to the amount of habitat affected. The presence of dogs causes wildlife to move away, temporarily or permanently reducing the amount of available habitat in which to feed, breed and rest. Animals become less active during the day to avoid dog interactions. Furthermore, the scent of dogs repels wildlife and the effects remain after the dogs are gone. The research is clear that people with dogs disturb wildlife more than humans alone. These effects reduce a natural area’s carrying capacity for wildlife, and also reduces wildlife viewing experiences for visitors.”
Disturbance and stress response: “Dogs cause wildlife to be more alert, which reduces feeding, sleeping, grooming and breeding activities, and wastes vital energy stores that may mean life or death when resources are low, such as during winter or reproduction. Animals release stress hormones and their heart rates elevate in response. When stress becomes too high, animals may flush, freeze, or hide. Repeated stress causes long-term impacts on wildlife including reduced reproduction and growth, suppressed immune system and increased vulnerability to disease and parasites.”
Indirect and direct mortality: “Dogs chase and kill many wildlife species including reptiles, small mammals, deer and foxes. A Canadian study found that domestic dogs were one of the top three predators that killed white-tailed deer fawns. In northern Idaho winter deer grounds, an Idaho Fish and Game conservation officer witnessed or received reports of 39 incidents of dogs chasing deer, directly resulting in the deaths of at least 12 animals (several other examples of wildlife deaths due to dogs are cited here). Dogs transmit diseases to wildlife and vice versa, including rabies, Giardia, distemper and parvovirus. Large carnivores such as cougars are especially vulnerable to domestic dog diseases including canine distemper.”
Human disease and water quality impacts: “Dog waste pollutes water and transmits harmful parasites and diseases to people. A Clean Water Services DNA study found that dog waste alone accounts for an average of 13% of fecal bacteria in stream study sites in the Tualatin River Basin. The City of Gresham found extremely high levels of E. coli bacteria in water quality samples of a very specific stretch of a stream, where dog feces were found along stream banks behind several yards with dogs.” In 1991 dog waste was labeled as a non-point source pollutant by the Environmental Protection Agency (EPA) due to it being the host to an array of diseases, as well as fecal coliform bacteria.
The Portland, Oregon Metro Government document cites many other statistics from an array of studies that supported their decision making.
So, if most, if not all of the reasons cited by the National Park Service are valid, many of which are backed by science, why does the U.S. Forest Service continue to allow dogs on backcountry trails, especially in designated Wilderness Areas where the land is supposed to remain in a natural state in perpetuity, and where impacts from human activities are supposed to be minimal? Seeing wildlife in their natural environment is one of the highlights of venturing into the woods and mountains for many hikers. This privilege should be vigorously protected. By no means am I advocating for the complete banning of all dogs on all national forest lands. However, I do believe we need more balance; more consideration for wildlife, and more protection of sensitive water sources. Doesn’t the U.S. Forest Service have a fundamental responsibility to protect the habitat and the long-term sustainability of wildlife? I believe the U.S. Forest Service and wildlife biologists should conduct studies to determine where dogs are appropriate and inappropriate on trails in our national forests and other wilderness areas. I also believe that stricter enforcement is needed for those who blatantly break existing rules, or any new rules. Certainly the fines that could be collected would pay for the increase in backcountry rangers who could be used to patrol sensitive areas.
Ramble On: A History of Hiking