A group claims Trafalgar Square's pigeons will starve after a judge said the birds cannot be fed until a decision is made about their future.
The mayor wants to rid Trafalgar Square of pigeons
Save the Trafalgar Square Pigeons is suing the mayor for £3,000 claiming he broke a contract to reduce numbers gradually by slowly reducing the feed.
The mayor said pigeons were being fed on the north terrace so there was no need to feed them in the main square.
A case in April will decide the their fate but they cannot be fed until then.
District judge Barry Lightman sitting at the Central London County Court turned down Save the Trafalgar Square Pigeons (STTSP) request for an injunction to keep feeding the birds until April's hearing.
He said the case should be heard in front of the circuit judge at the earliest possible date because it was "an issue of public importance."
Mr Lightman told the preliminary hearing that "in my view the claimants will not succeed at trial".
But he said their argument that there was a contract between them and the mayor should be heard by a circuit judge.
A spokesman for the Mayor of London Ken Livingstone said the mayor's office had initially given permission gradually to reduce feral pigeon feeding "as part of a policy of making the square more pleasant for public use".
He said there had, however, been "an attempt to resist this approach by animal rights activists feeding feral pigeons on the north terrace".
The north terrace is the only section of the landmark that does not fall under the control of the mayor - it comes under the jurisdiction of Westminster City Council.