With cinema-goers currently enjoying the tale of Fantastic Mr Fox, the real-life version is on the increase in the Bristol area, according to the UK's expert on the species.

The disease mange virtually wiped urban foxes in Bristol in the early 1990s, but they have fought back and there are now an estimated thousand breeding adults in the city.

That's nothing like the level of previous times – in fact numbers are only half what they were at their peak – but Professor Stephen Harris, based at the University of Bristol, says the city is a great place for them to thrive.

Professor Harris, based at the School of Biological Sciences in Woodland Road, has been fascinated by foxes since he was a small boy growing up in the east end of London after the war when foxes moved into the bombed-out landscape.

Bristol, with suburban estates full of semi-detached houses, big gardens and open spaces is ideal for the animals.

"Bristol is a self-contained city, there's lots of that housing stock around," says Professor Harris, who studies foxes from the back garden of his Stoke Bishop home.

"Having a very hilly lay-out, the city was developed by hand, not by machinery, and bits that were too steep to clear – rocky bits – have been left so you've got little refuges throughout the city that animals like."

Professor Harris knows the foxes that visit his own garden as individuals. "It's rather like a soap opera," he says. "Foxes don't live that long. Fifty per cent die every year, there's a big turnover. Things happen, like accidents, and you have the opportunity to watch the pattern of their lives, how they interact and how their social status changes.

"They are highly intelligent animals, many people say they are more intelligent than dogs. They are both intelligent and interesting. Like any animal that you would consider as being moderately intelligent, they have characters. As all dogs are different, so all foxes also are."

Professor Harris says that as he watches some together in his garden, he notices their characteristics. Some are very relaxed, some are more wary, and some just seem to love being out in the garden with him.

One in 10 households in the northwest Bristol area (Coombe Dingle, Henleaze, Sea Mills, Sneyd Park, Stoke Bishop, Westbury-on-Trym and Westbury Park), where he and his research team carry out their studies, regularly leave food out for foxes.

But while Professor Harris says watching their behaviour can be rewarding, he advises people against regarding foxes as pets.

Leaving food in the garden is perfectly okay, he says, but problems can start when people try to make foxes tame enough to eat from their hands.

"If they become tame they can become problematic," Professor Harris says. "Some people can be quite concerned if they see a bold fox walking up to them, thinking it's going to attack them rather than just because they are so used to approaching people.

"Some people feed them in their kitchen and, of course, that's a problem because they can go into other people's houses and wreck them, damage them, and cause mayhem. I recommend just putting food in the garden and watch them come."