dog walking and birds

September 26, 2007

in Science

Four-legged friend or foe? Dog walking displaces native birds from natural areas. P. B. Banks and J. V. Bryant. 2007. Biology Letters. Early online, DOI:10.1098/rsbl.2007.0374.
This paper has received a lot of press as it is on a perennially hot-button topic. Australian researchers did a careful examination of the impacts of dog walking at 90 sites near Sydney. They looked at a variety of bird species within 50 meters of a trail, and observed their reactions to walkers with dogs, walkers without dogs, and neither. The results were clear:

“…Dog walking in woodland 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.”

It should be noted that all dogs were leashed, and it is my experience that dog walkers frequently let their dogs off leash in wooded areas (I am not alone). That this effect was evident in areas where dogs were commonly walked as well as places where dogs were not allowed indicates that birds do not get used to dogs nearby. Ground-dwelling bird species were impacted at a higher percentage, but people without dogs caused only about half the disturbance.

Before I hear from irate dog owners, let me address some of the JPS (just plain stupid) arguments that tend to crop up. You can see many of them in one form or another in the comments of this random article on the paper.

  • Development/habitat loss/humans in general are the biggest problem facing birds, not dogs. This is true. Heart disease is one of the leading causes of death in the United States. That doesn’t mean we ignore every other large and small disease, disorder, or injury that causes mortality.  If we added up the impacts of every other threat to bird survival, I’m sure it would come close to or equal the impact of habitat loss. If we all do our part in reducing or eliminating the lesser impacts, the world would be a better place.
  • Cats are worse. Outdoor cats are awful, I agree. Keep them inside. Then walk your dog around the block or take it to a dog park. And see above.
  • These people are hypocritical. Have they never killed a bird with a car? Had a bird hit their window? See point number one, again.
  • Nature always finds a balance. The birds just go somewhere else. The “balance” is increasingly ending up in favor of a few highly adaptable species and simplified, altered ecosystems. In a rapidly urbanizing world, these birds end up not having another place to go, or must attempt to survive in marginal, inappropriate habitat, or in increased competition with other birds seeking the same safe haven.
  • The birds just fly away then come back. There is no lasting impact. Many studies have looked at how disturbance (predator, human, etc.) has long-reaching effects on birds, such as time away from foraging, increased energy output, nests left untended, chemical reactions in the body that reduce fitness, etc.
  • I suppose foxes and wolves will be next! Because of their territorial nature (and the fact many do not survive well in urban areas), other canids do not occur in the density and abundance of domestic dogs. My study site is part of a 300-acre urban natural area. There are red and gray foxes and coyotes. There are more dogs walked through our area — where they are prohibited — in any given week than the population of all three native candids combined. And that’s not counting the feral dogs, which have been released or dumped there.
  • Dogs have a right/I have a right to walk wherever I want. Nobody is trying to tell you can’t walk your dog. Just don’t walk it through natural areas. If you can’t find someplace near where you live to walk your dog, or your dog needs to run free, maybe you need to live someplace else or not have a dog. I don’t have a horse. By the way, if dogs have rights, so do birds.
  • Maybe it was the researchers that scared off the birds. What are the effects of researchers on bird populations? Obviously, having a human observer in place creates an effect. However, that effect was equal for all observations, and the dog impact was still seen and profound. And there are negative impacts associated with some types of wildlife research, but all researchers have an ethical and legal obligation to minimize these impacts or not perform the studies. At least we end up learning something from research; we don’t learn anything from disturbing birds walking our dogs.

Usually, I summarize two or three papers in my TOC Alerts. I’ve rambled on enough, though.

John September 26, 2007 at 11:00 am

I was surprised not to get any angry reactions when I linked to this a week or two ago.

John September 26, 2007 at 11:05 am

Oh, and I think that your response to the "nature finds a balance" argument is very good. It becomes a lot harder for natural ecosystems to bounce back when we keep inflicting artificial or domesticated elements into them.

Phantom Midge September 26, 2007 at 8:19 pm

I found this to be very interesting and I'm glad there is some research being done on this issue. Now, I am a dog owner and love to take her with me on walks but I can also be responsible and keep her on a leash.

Of course, this may be because I used to work as a park naturalist I got tired of asking over and over for people to please leash their dogs (and, yes, most responses involved swearing).

More than just the intrusion/startle factor of dogs, I am wondering if anyone has studied the impact of dog waste on natural areas? Another aspect that many dog owners around here seem to neglect is to pick up after their pet. (They give a bad rap to good dog owners everywhere)

Nuthatch September 26, 2007 at 8:35 pm

I imagine not too many people are lining up to do that study!

Mark Nicholson September 28, 2008 at 9:07 pm

I notice this study is done on the fringes of Sydney, presumably quite nice areas and certainly > 30 meters of woodland. But my council is using this study as evidence to restrict dogs in a long standing off lead park (all but a dedicated dog park). The park is mainly open ground (a former tip) deep in an urban setting bordering an open drain and golf course. I am a dog walker and do also agree with the need for greater protection for native flora and fauna in urban environments. And for that reason I don't not take my dog to sensitive areas at all (and live in an area where there is/was a suitable area). However I don't think it's your intention to have your research misused in this way – is it?.

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