Pollution was so bad in the French capital last week that the authorities advised asthmatics to stay at home and halved fares on public transport in a drastic attempt to lure drivers from their cars. Although weather conditions and the amount of traffic were similar to London's, it is argued that Paris has taller buildings and narrower streets, trapping the foul air. But in the middle of August every resident who can go away does so, leaving the pollution to the tourists - and the pigeons.
"Generations of pigeons in Paris are terribly dehydrated and malnourished," says Nadia Fontenaille, president of the Society for the Protection of City Birds. "What's more, these neglected creatures have very delicate pulmonary systems, and the pollution can have a dangerous effect on their health."
Until about 20 years ago the problem of overpopulation in the pigeon community was kept under control by a bird feed with a difference - it contained a contraceptive with a 97 per cent success rate. But the drug was taken off the market and replaced by a much more expensive and less effective alternative. The result has been an explosion in pigeon numbers, which in turn has caused malnutrition.
Feeding pigeons in Paris is a punishable offence, carrying a fine of up to pounds 300. Lack of food and water, combined with the effects of pollution and illness, means the death rate is high: more than two-fifths of all young pigeons never reach adulthood and nearly a third of adults die each year according to Techmo Hygiene, a pest company.
Those that escape natural death often meet a more brutal end. Instead of contraception, thousands of pigeons are captured and legally asphyxiated each year by the authorities to control their numbers.