Adventures Among Ants - Mark W. Moffett [14]
In addition to showing me the Botanic Gardens, Paddy took me in his battered white Nissan on expeditions to Singapore’s watershed, the Bukit Timah Nature Reserve. After several hours rooting in the mud and stuffing specimens into vials, we would finish our day with a stop for a drink. Oblivious to our jungle-rat appearance, he’d drive to one of Orchard Road’s fancy hotels and, shuffling into its gleaming five-story foyer, demand two Tiger beers from the bar, all the while holding his insect net like a national flag. Libation consumed, we would then retreat to his flat, where his wife, a chemistry professor of Indian descent, kept a motley herd of little dogs. Sitting at the kitchen table, Paddy would scrutinize the day’s catch, never raising his eyes from the magnifying glass. Meanwhile the dogs, announced by a rumble of paws on the tile floor, ran in formation like a migration of African wildebeests, circuiting the house every minute or two.
After another round of beers from his fridge, Paddy would drop me off at what came to be my favorite part of the Botanic Gardens, a seldom-visited back section where I began to understand how deep were the convergences between marauder and army ants. The foraging behavior of both displays a specific set of characteristics that, in scientific fashion, form a sequence in my head. In brief, (1) the workers are tightly constrained by one another’s activities, such that while individuals constantly enter and leave the raid on a trail to the nest, (2) those in the raid nevertheless avoid spreading apart, so that the raid retains its existence as a cohesive whole; in fact, (3) adjacent ants stay close enough together that communication between them can be virtually instantaneous. (4) This unit moves along a path that (5) is not controlled by any steadfast leader or leaders within it, (6) nor by scouts arriving from outside. Indeed, (7) their movement does not target a specific source of food, (8) nor is progress dependent on finding food en route, because the ants are drawn forward not just to meals but also to the land ahead; further, (9) the advance can continue across “virgin ground,” because advance doesn’t require cues left by prior raids. Finally, (10) all foraging is collective. No ant sneaks out to grab lunch on her own.
These features basically define what we mean by the words group and forage in these mass-foraging ants. The first three describe a particular sort of group in which proximity turns out to be essential: no marauder ant searches alone for any significant distance.16 That means food never has to be abandoned while help is enlisted. Overpowered quickly, prey is unlikely to be stolen, or escape, or have occasion to defend itself. The other attributes describe a certain kind of foraging in which the searching group has no predetermined destination and need not take any particular course.
All these details took me months to work out in that back section of the gardens. I was largely hidden there from the heavy tourist traffic, though I do recall one passing wedding party that was shocked and then fascinated to see me on my hands and knees, counting ants performing the superman task of carrying a lizard egg. The bridesmaids lifted the bride’s veil as she too stooped to take a look.
2 the perfect swarm
At the end of my first week in Singapore I had my first clear view of a swarm. It was late afternoon in a remote corner of the Botanic Gardens. Paddy Murphy sat nearby, smoking a “fag” and examining a silverfish on a tree. I had spent the previous hour on my hands and knees following a trail of marauder ants that were obviously on a foraging expedition, because they were bringing back all kinds of prey. And there, suddenly,