What keeps the macaques in the Upper Rock

By Brian Gomila, Monkey Talks Gibraltar
Residents of the South District have reported a spike in macaque roamings in recent weeks. From a single macaque inside a kitchen in Naval Hospital Hill to reports of a small gang passing through Europa Walks Estate and hanging in and around as far down as Rosia Battery. The question that gets asked the most by those affected is simply, why? Why do they come down? Inevitably the suggestion that they are coming down due to lack of food also gets thrown in the mix.
Whilst making no attempts to justify these undesirable roamings, nor the nuisance macaques can cause within urban areas, perhaps the question to ask is why not? How come scores of macaques don’t make it a habit of coming down more often? After all, its not like there are any physical barriers preventing them from doing so. Macaques are of course not tied down to any social restrictions either. They are habituated to humans (and within reason, traffic) and even associate urbanised areas with household refuse and with that the opportunity for easy pickings. Tourism has been at all but a standstill for a year now and whilst some would have predicted the macaques to miss their daily fix of treats and venture down in search of them, these past 12 months has, if anything, so far seen less roamings than other years. So, what keeps them in the Upper Rock then?
Macaques live largely within the boundaries of their troop’s established territory. Inside their territories, macaques find shelter usually in cliffs, natural forage, and living in large groups they can socialise and find potential mates and safety from other troops. You could therefore argue that the resources within each territory meets the macaques’ day to day needs. In Gibraltar, the limits of these territories laterally along the Upper Rock are determined by the territories of adjacent troops. In addition, supplemental daily provisioning of fruits, vegetables and grain by the dedicated Macaque Management Team, freshwater ponds and the inevitable treats from visitors at tourist hotspots serve to further reduce the macaques’ territories.
However, macaque troops are dynamic social systems. Male migration, the death and subsequent replacement of a matriarch, an increase in numbers of a particular demographic, seasonal changes including daylength and weather, disturbance from a nearby construction site - all these can bring about social changes and habits to the troop as a whole or certain cohorts, which can result in atypical roamings and urbanisations.
From personal ad-hoc observations over the years the reasons why macaques venture away from their territory onto urbanised areas are manifold and cannot be attributed alone, if at all, to the common misconception that they are not being fed properly or they are hungry. Instead, the clue usually lies in the identity of the individuals that compose the ‘splinter group’. Some of the more common groupings include:
A lone adult male – this is more than likely a peripheral (or rogue) male who has just emigrated from a troop and is temporarily living a nomadic existence until he eventually integrates fully into a new troop and its territory.
A small group of less than 5, mainly adolescent males, usually accompanied by a slightly older individual may, in layman’s terms, represent a group of youths with a ringleader spending time away from their families exploring their neighbourhood and inevitably getting up to mischief in the process.
A sizeable group of approx. 10 or more, composed primarily of females with one or two males and their young, with sustained incursions over a relatively long period of time and spending the night away from their natural territory, is probably a matriline that has splintered off and might be the precursor of an eventual group fission of this matriline from the main troop.
Seasonal sporadic incursions involving the majority of a troop, say upwards of 25, in which both sexes and all sizes/ages are present, might represent an exploratory foraging trip and usually coincides with the fruiting of a particular tree(s), for instance there are various fig trees in the vicinity of Gardiner’s Road.
A young adult male with one or two females and their infants in and around the mating season may indicate a subordinate male, courting females away from the group to mate opportunistically out of sight from the more dominant males.

Naturally, in all the above scenarios the macaques exhibit opportunistic behaviour meaning that even in the event that the overriding reason they strayed from their territory was to explore their surroundings they are not going to pass on the invitation of an open kitchen window or accessible household refuse. Indeed, such a find is sure to spur them on more readily and in greater numbers the next time. i.e., the roaming was worth their while. If to this you also take into account the fact that the physical features of buildings such as rooftops and terraces etc. provide the macaques with a safe vantage point, it is not difficult to understand why buildings and fortification walls might appear attractive to the macaques, acting almost as oases in a labyrinth of busy, more exposed roads and open spaces and act almost as a makeshift territory where the macaques can, if unchallenged, feel at home.

In this respect the unrelenting work of the Macaque Management Team, at times undervalued, is crucial in challenging the macaques and gallantly coaxing them back to their territory - in short, making the macaques’ roamings not worth their hassle.

The cohort which are moving freely through the South District consists of one large male, at least one adult female with an infant and two or three adolescent males. They are part of the Levant Battery Troop. This troop established itself in 2003 when Porky’s matriline fissioned from the Royal Anglian Way Troop the year before. It has since become one of the biggest troops, now consisting of 50 strong. Their established territory is also arguably one of the largest, spanning Windmill Hill Flats from the East above Europa Advance Road to the West along the cliffs above Europa Pass and Genista House, although they can be seen in greater numbers congregating in and around Europa Advance Road refuse tip and the cliffs to the East of Lathbury Barracks and Levant Battery itself where they are provisioned with food by the Macaque Management Team. For some time now this troop has been showing signs of unrest. Being quite a large group, it appears less cohesive, and the troop can often be seen exhibiting fission-fusion behaviour whereby the troop breaks up into smaller, more familiar sub-groups, but generally reconvene during the evening.

Although a similar spate of roamings were reported in summer of 2019 during which macaques were repeatedly seen in and around Europa Point, crucially it would appear that the sub-group venturing to Rosia have been spending the night beneath Fortress Headquarters. This could represent a game changer and the next few weeks will be telling of how this latest macaque urbanisation unfolds.
One thing is for sure; they are going to give the Macaque Management Team a run for their money and with longer days ahead and the macaques gaining in confidence things might get worse before they will improve. Residents can do their bit by not allowing the macaques to move freely through their property unchallenged and thereby gain in tenacity.
Residential Estate Managers and refuse collectors might also wish to consider ensuring that bin enclosures are kept closed and bins only left out in the open in time for refuse collection.

Brian Gomila is a Primatologist and founded Monkey Talks Gibraltar. He wrote this article following recent macaque roamings in the South District.