Effects of Dogs on Wildlife Communities

This is a very important study in the Boulder community as it was user to justify the exclusion of dogs from Hall and Heil ranches North of Boulder and it continues to feed policy discussions

The paper spends several pages referencing literature on dogs from around the world, much of it from the “third world”–which establishes that feral dogs or domestic dogs running wild have the capacity to do harm to other animals. While some of this is interesting, such as the fact that a dog would eat a wombat in Australia, it is not really relevant to the issue of whether dog owners should be able to recreate with the family pet on Boulder Open Space.

The real focus of the study is to determine what, if any, effect the presence of dogs on a trail corridor might have on the presence of other mammals. To that end the study uses a combination of remote cameras, track plates, pellet plots, and scat surveys to look at trails in Hall and Heil ranches where dogs are not permitted to compare them to sections of trail in Boulder Mountain Park.

The conclusions in general are:

– Mule deer tend to move away from trails that people use for recreation regardless of             whether the dogs are also allowed on those trails

– Where dogs are NOT allowed “deer activity was decreased within 50 m of trails.”

Where dogs are allowed, “deer activity was decreased within 100 m trails.”

– Small mammals such as squirrels, rabbits, chipmunks, and mice also show decreased
activity close to trails where dogs are allowed, “though these species activity
resumes normal levels within 50 m from trails…”

– There were more prairie dog burrows within 25 m and 10 m of trails where dogs were    not present than where dogs were allowed, although the presence of dogs did not significantly affect presence of prairie dog burrows within 50 m of such trails.

– This ones interesting, “Native carnivores” show increased activity along trails that permit dogs as opposed to trails where dogs are not permitted. This finding was particularly true of the red fox; although bobcats were the exception to this finding, as measures of bobcat activity decreased on the trails that allowed dogs.

The key point here is that there is no reference to the the presence of dogs on some trail corridors tending to decrease the activity of certain mammals within 25, 50, or even 100 m of the trail. Does that have any impact on the ability of the species to feed, breed and survive?

Lenth et al certainly know their stuff as far as methodology is concerned, but the results do not suggest that dogs in Boulders Open Space have a significant impact on the wildlife.

A similar report is on the effect of dogs on Night Jars, good methodology but the conclusion is really that dogs dont actually have an impact on the birds in the study to successfully breed..

As this report has been used to make public policy, its important to note that it does not try to address the key issues. This study will simply be regarded by those who hear of it, or see it cited, as proof of something far more than was actually studied or demonstrated.