The City's Own Strand of the River

As we walk along the southern bank of the Danube Canal, I am reminded of how important this park-lined waterway is to the natural balance of life in Vienna; how integral it is to the city, while remaining a world apart.

I turn to my companion Franz Essl, an ecologist with the Austrian Environment Agency, who agrees. It’s more than just a question of ecology.

"It’s important for other reasons," he says. "About 200,000 people live within a couple of hundred metres of it. For some, it’s their only regular contact with nature."

Just a few moments ago, I had waited for Essl on Friedensbrücke – one of the bridges that spans the canal. It was morning rush hour and the bridge was overrun with schoolchildren, people on their way to work and an incessant flow of cars, vans and buses. A large dump truck held up traffic as men in high visibility jackets made repairs and a steady run of trams added to the tumult. Sometimes, even in Vienna, things can get a little clamorous. But nature can provide respite – one reason that Essl believes the Danube Canal is so important.

Wending its way through the city for around 17km and touching some seven districts as it goes, the canal is a remnant of what was once a peripheral arm of the Danube River, before it was regulated in the mid-nineteenth century to protect Vienna from flooding. A map shows how the canal cuts much more of a meandering path than the re-routed river, which now passes – broad and straight – to the north-east of the city.

On the canal’s cold, black water, a cormorant dives for fish for minutes at a time. Small flocks of black-headed gulls in winter plumage are dotted about, and individuals shiver down on thin wings to skim the surface in search of food. The odd mallard splashes nearby and hooded crows call intermittently. A grey heron is a regular on this patch, too, but is not about today; instead, two swans glide across the water.

"Actually, the swans are alien to Austria," says Essl, following my gaze. "The first breeding pair wasn’t recorded here until the 19th century."

On the canal bank, Essl brushes apart snow-covered brambles with his boot to expose small holes in the mud. "It could be muskrat – Ondatra zibethicus," he says. Introduced from North America for fur, muskrats are strong-swimming, medium-sized rodents, who mark their territory with a musky odour secreted from scent glands. Sensing my excitement, Essl goes one better. Last year, he tells me, he saw that several trees had been gnawed and felled – evidence of a beaver, but he hasn’t seen it for six months or so.

We stop near a native Mediterranean species that is flourishing on the canal bank – a large fig tree, or Ficus carica. It seems to be decades old and we ponder its origins – discarded seeds at a family picnic during the 1960s, perhaps.

But now we’re cold and need a coffee to warm us, so we leave the canal to rejoin the city, which, just a metre or so above us, seems frenzied in comparison.