New advice from the Department of the Environment gives nine ways of getting rid of the geese, from shooting them and breaking their necks to the more delicately-styled 'habitat adjustment' - taking away their island strongholds in park lakes, for instance.
According to the Canada goose working party, the birds' remarkable powers of excretion and reproduction require a long-term management strategy. Without controls, the population, 19,000 in the 1970s and over 60,000 now, could more than double by the end of the decade.
'A large flock, defecating every few minutes, can deposit a great deal of excreta,' the guide says. A mature Branta canadensis will produce one large dropping every three or four minutes, generating roughly a hundredweight of excreta a week.
Canada Geese - A Guide to Legal Control Methods, is the latest instalment in a controversy which has set ecologists against bird-lovers, embroiling figures such as Paul McCartney and Carla Lane, the television scriptwriter, whose scheme to 'rescue' more than 150 geese from Battersea Park last month and remove them to Mr McCartney's estate in Sussex was aborted when Wandsworth Council shot them.
Marksmen using silencers have culled the flock in St James's Park. More bird-friendly control mechanisms such as egg-pricking take longer to have any effect.
The geese have no predators and are protected under the Wildlife and Countryside Act. Under British and EU law, they cannot be shot merely because they are champion excreters. However, scientists are examining whether their droppings contain pathogens harmful to humans, which would give new reasons for culling.Reuse content