CRI听力:Impacts of Air Pollution on Birds

An Australian report has shown that urban life is not ideal for birds, especially the native White Ibis.

The Ibis is found in most Sydney parks and rubbish tips, scavenging for food and wreaking havoc with flower beds.

But now the long-legged bird has become a barometer of the city's health.

A team of scientists tested the pollution levels in Ibis eggs over 11 sites across the city's coast.

The findings were compared with those nesting in natural environments further inland.

The results show that things are far from pristine in the cities.

The researchers found that the urban-dwelling Ibis have much higher levels of toxicity than their countryside counterparts.
Research scientist Camila Ridoutt said the imbalance was significant.

"The pollutant levels in urban sites are much higher than those found in the inland sites."

In fact pollution levels were as much as seven to nine times higher.

Camila Ridoutt says the ibis eggs found in the city were smaller, lighter and thinner-shelled. She says this suggests fertility complications.

"You can infer there's a relationship with the higher pollutant levels and the potentially lower reproductive success in urban areas compared to inland areas."

Those who've had their lunch stolen by the stalking bird may not be concerned about its demise, but it's not just the ibis that's in bad health.

Richard Kingsford from the Australian Wetlands and Rivers Centre research group or AWRC says birds of prey will inevitably be exposed to the toxins.

He says Australians should learn from other countries that have had problems with pesticides.

"And other animals feed on those, particularly things like sea eagles for example. And we know from the 1960's in North America when really the whole issue of DDT broke wide open when people found egg shell thinning in birds of prey - eagles and so on - and so that's a concern. The higher up you get in the food chain the more you get the concentration of these sorts of pollutants."

It's a worrying sign for cities with avian residents.

But for now scientists are concerned toxicity levels could increase in the larger inland flocks, where consequences would be devastating.

For CRI, I am Li Dong.