New research showing that dog-walking in bushland significantly reduces bird diversity and abundance will lend support to bans against the practice in sensitive bushland and conservation areas.
Until now, arguments and debate about the ecological impacts of dog-walking have remained subjective and unresolved because experimental evidence has been lacking.
But the first clear evidence that birds perceive dogs as predators and avoid dog-walking areas is published today in Biology Letters, reporting research by UNSW biologist Peter Banks.
"We found in field studies that dog-walking in bushland causes a 35 percent reduction in bird diversity - the number of species - and a 41 percent reduction in abundance - the number of individual birds in an area," says Dr Banks.
"The effect occurs even in areas where dog-walking is common and where they are prohibited, indicating that birds don't become accustomed to continued disturbance by dogs.
"This evidence clearly supports the long term prohibition of dog-walking from sensitive conservation areas," Banks says.
The revelation has immediate implications for popular recreation activities such as bird-watching and eco-tourism, where visitor satisfaction has a strong relationship to the number of species seen.
The experiment was conducted at 90 sites in the Hornsby-Berowra-Cowan regions, 35kms north of Sydney, Australia. The area was chosen because it contains remnants of bushland with trails that are either frequently dog-walked or where dog-walking is prohibited.
The experiment used three conditions to study dogs' impact on birds: (1) a person walking a dog on a lead on a trail; (2) a person walking alone on a trail; (3) a control condition with no dog walking or humans.
Observers monitored all native birds seen or heard within 50 metres of a 250-metre trail. Monitoring commenced 20 seconds after the walker/dog-walker had set off and continued for 10 minutes.
Ground-dwellings birds appeared most affected: 50 percent of bird species observed in control sites were absent in dog-walked sites. The effect of dog-walking was most pronounced in the area immediately adjacent to the site where dogs were walked, according to Dr Banks.
"There were 76 fewer birds within 10 metres of the trail when dog-walking occurred compared to control sites, suggesting birds were seeking refuge away from the immediate vicinity of threat."
The particular sensitivity of ground-dwelling birds to dog-walking was of concern because it could lead to a "cascade" of behavioural changes that could further threaten these species, Dr Banks says.
Dog-walking was also likely to affect the accuracy of wildlife surveys that are used to map bird distributions around the world.