Taking your dog for a walk could be having an impact on local birdlife, a study suggests.
Our four-legged friends are viewed differently by birds
An Australian team found dog-walking was prompting birds to take flight, causing numbers to plummet by 41%.
The researchers, writing in the Royal Society journal Biology Letters, said the birds were fleeing because they viewed the dogs as potential predators.
Charity Birdlife International said the longer-term effects of the dogs' presence now needed to be looked at.
Peter Banks, the lead author of the paper from the University of New South Wales, said: "There is an obvious link between people wanting to walk their dogs and the potential disturbance effect on wildlife, and there has been a lot of debate around this, so we wanted to resolve this issue."
The researchers looked at 90 woodland trails a few kilometres north of Sydney, half regularly used by dog-walkers and half where the animals were prohibited.
Dogs were walked, on leads, along the 250m-long (820ft) trails, followed 20 seconds later by an observer who counted the birds seen and heard. The experiment was repeated for walkers without dogs and for a control scenario where there were neither walkers nor dogs.
Dr Banks said: "The key finding is that dog-walking certainly does have an impact on birds - and we were quite surprised by the magnitude of the impact."
The team found that dog-walking was causing bird numbers to drop by an average of 41% at each site and the numbers of species counted fell by 35%.
The results were similar in sites often frequented by dog-walkers and those where the practice was prohibited, suggesting that birds did not get used to the dogs' presence, despite frequent encounters.
Humans walking alone also caused a disturbance to bird numbers, but on average less than half of that caused by dog-walking.
The team also found that two humans walking together without a dog had no more impact on the birds than a lone walker without a dog, suggesting that birds were responding uniquely to the presence of dogs.
Dr Banks said: "The birds were clearly showing an aversion to dogs - they clearly perceived dogs as a potential predator."
The team is now planning to look at how long the birds stay away for, but Dr Banks said that even if it was a short period of time this could have a potential impact on nesting and feeding.
The researcher added that the results of the study could be useful for conservation and wildlife management, and although the work was carried out in Australia, the results were applicable to other areas around the world.
He said: "We hope that this information will be useful when people are weighing up decisions about access by people and by people with their dogs.
"For example, in places where there is a very high value conservation area, perhaps dogs really shouldn't be allowed there; but there may be other areas where those conservation issues are not as great and maybe those are where dog-walking can be allowed."
Martin Fowlie, a spokesman for Birdlife International, said the study confirmed what conservationists already suspected.
He said: "This is not a surprising result; there is already evidence that dogs can disturb birdlife, but it is interesting that someone has now quantified it.
"It would now be really interesting to see how long those reductions in bird numbers last, to see whether it is a few minutes, hours or days."