Tehran's notoriously bad air pollution has long
been a health hazard for its 12 million people, but now the toxic mix of fumes
has sent a different set of residents fleeing – the city's black crows.
Environmentalists say the
hitherto pollution-resistant population of crows have fled in large numbers in
recent days after air quality reached crisis levels. Unregulated urban
development has also destroyed the birds' habitats.
The crow exodus occurred less
than three weeks after high levels of carbon monoxide and other gases in the
air drove off other species of bird, including nightingales and pigeons.
Experts fear the departure of the
crow – long decried in Iranian culture as a symbol of bad news and gossip –
could be the death knell for wildlife in Tehran,
where many plants have already lost their smell and colour as a result of the
polluted atmosphere.
Mohammad Bagher Sadough, the head
of the city's environment agency, said the crow exodus was a sign of a
disturbed ecosystem. Eventually the remaining bird species will also leave,
turning the city into an urban desert of high-rise buildings and traffic jams.
"Pollution is not the only
element in the flight of crows and others birds, but it is among the most
important," he told the Mehr news agency. "Habitats have been
destroyed and the perpetuation of bird life has become impossible.
"The continued existence of
crows, particularly with the departure of other birds, had given us hope that
wildlife could survive in the city. With their migration that hope is fading
and our concern over the destructiveness of urban environments has
deepened."
Dr Jamshid Mansouri, an Iranian
biodiversity expert, said the birds would be forced to seek new habitats in
rural environments, where they were threatened by predators and possible
extinction.
"If the process continues,
eventually no birds will be able to live in
The polluted air is traditionally
at its worst in winter, when a thick curtain of smog hangs over the city for
days on end – frequently forcing residents to wear protective face masks. On
occasions the poor air quality has prompted the authorities to close schools
and urge people with respiratory ailments to stay indoors.
The city council estimates that
80% of the toxic gases are caused by cars, with large numbers of motorbikes
compounding the problem. A new report by