Contraceptives will be hidden in the monkeys' food or some of the females will be given implants to prevent pregnancy. Their population has grown four-fold to 250 in the past five years, since a law was passed making it an offence to kill them. Thirty monkeys are born each mating season.
For the British forces on the rock, renegade packs of the apes already represent one of the biggest threats to their positions since Gibraltar was handed over by the Spanish in 1704.
The marauding tailless monkeys have moved onto Ministry of Defence property near the top of the rock and have begun ripping sensitive and expensive equipment from mountings and chewing up cables. They have also be known to lob stones at passers-by.
Tony Carter, manager of the military estates on the rock, said: "We have had people out from Zurich University looking at ways that we can control them, either by contraception, which the Gibraltar government is looking at, or shipping some of them out to America, where they have not got any Barbary macaques. Culling seems to be a dirty word among Gibraltarians."
Paul Montegriffo, director of Sights Management, which has looked after the apes for the Gibraltar government since 1992, agreed. "Culling is not an option which goes down well locally as we have a particular affection for the monkeys. The main option is contraception of some sort, whether it be administered orally in their food or a series of implants is placed in several females to control the population."
The natural habitat for the macaque is in the Atlas mountains and pine forests of North Africa and it is believed that they were brought to Gibraltar during the Moorish occupation (700-1500AD). The British are recorded as bringing more macaques from Morocco as pets in 1749.
For many years the monkeys were forced to fight for their survival against eagles which carried away their young. In turn, the apes raided the eagles' nests for eggs.
The eagles were finally driven from the rock by the hordes of herring gulls, leaving the apes without a natural enemy and allowing their population to explode.