A touch of light: the tireless energy of ants

15 September 2020

3907

By MIKE GILLAM

All photos © Mike Gillam

Ants seem to be everywhere. There are two pesky species of black ant at our place – one tries to build nests in the roof, the other sends raiding parties under the back door and into the kitchen bin.

A further two innocuous species visit the bathroom. One, incredibly small and slow moving, simply passes through the window flyscreens, has a drink at the sink in small numbers and goes back outside. No problem.

Sugar ants, Camponotus sp (probably C.terebrans) have a nest outside and during summer small numbers of workers, never more than a dozen, magically appear inside our toilet bowl.

This alarming behaviour was repeated regularly and I began to worry that the strange presence of sugar ants might indicate that I was pre-diabetic. Recently I found some research that explained the behaviour while dispelling my concerns.

Led by wildlife ecologist Associate Professor Topa Petit, the Kangaroo Island-based research found that sugar ants prefer urine over sugar:

When I first noticed the ants swarming to scavenge urine, it was purely by accident…

Camponotus terebrans are undoubtedly looking for urea in urine because, similar to certain other ant species, a bacterium in their digestive tract allows them to process urea to get nitrogen for protein.

This remarkable ability to extract urea from dry sand not only shows how sugar ants can survive in arid conditions, but also, how they might reduce the release of ammonia from urine, which leads to the production of nitrous oxide, a highly active greenhouse gas.

Our sugar ants are largely nocturnal so it’s no problem working around them. One year they managed to get inside a loosely fitted lid on the honey jar. I know what you’re thinking, contact tracing from toilet bowl to honey jar! Fortunately, the honey was essentially finished and unfortunately the ants were dead; a salutary lesson about storing the honey in the fridge during summer. I took a photograph and gave them and the jar an appropriate funeral.

Ant biodiversity is heavily impacted by grazing and these factors combine in the highly productive mulga shrublands. Some of the best examples of ‘protected’ old growth mulga occurs, not in national parks but within the narrow incidental reserve created by road corridors. Here a wonderland of ant architecture is expressed in the contrasting turrets, spires and circular dam walls constructed by different species.

Nest structures provide a defensive high ground advantage with narrow entry slots and raised barriers that also keep out windblown particles and debris. Critically, raised nest walls protect a colony from occasional sheet flow that would flood underground cities with devastating consequences.

Ants and termites are often referred to as the earthworms of the desert in acknowledgement of their role in soil turnover and aeration, promoting moisture infiltration thereby maintaining topsoil health.

Anyone who has spent time in the mulga during or after summer rain will confirm the presence of unseen holes and vents, countless pores in the mantle of an ancient landscape, back doors and escape entrances, blocked holes and pop holes, that open to release the exodus of winged alates of termites and ants or emergent burrowing wasps and moths.

The synchronised emergence of winged ant males and queens from a great many colonies overwhelms the waiting predators and mixes the gene pool. The birds, both residents and nomads, are waiting of course; as the stream of protein rises, kilo after kilo, more birds join the fray.

Magpie larks and babblers congregate around the points of egress, frantically gulping down the indecisive flying ants. In the sky above mixed flocks of woodswallows, crows and kites deftly snatch alates from the air. Circling kites are especially fond of the alates, catching and eating them on the wing. Fragile virgin queens are held in great clenched claws thrust forward to meet bowed heads and hooked beaks.

While summer rain can be a signal to the established colonies to send out the next generation, to go forth, form new colonies and multiply, in contrast winter rain must be endured. Early one morning I witnessed amazing behaviour at the entrance to a colony of meat ants, Iridomyrmex purpureus.

It was July and raining heavily and I rushed home for a camera, tripod and umbrella. The nest in question was linked via ant highways to several others, essentially satellites, of a super colony that dominated an area of perhaps 100m2.

Located on a gravelly rise the ant nest was safe from runoff or sheet flow. Its single nest entrance lacked any raised features and was surrounded by bare pavement, an exclusion zone fiercely defended by ants with attitude. Responding to the threat of driving rain, meat ant workers were using their tightly massed bodies to form a living plug thereby sealing off the nest entrance. This colony behaviour was very effective and completely new to me.

Years later I photographed a late spring emergence of meat ant queens. High priestesses with gleaming green heads and gossamer wings, lined up seeking the breeze, their puny male suitors ready to follow in the flight of their lives (image at top).

Ants are amazing. I’ve watched various ants tending their ‘herds’ of aphids and mealy bugs for their sweet exudate and on occasion cutting up freshly emergent fungi and removing the pieces, doubtless food for the growing larvae.

Spinifex ants construct a network of surface tunnels made from sand glued together with resin. These structures protect the workers from predation and high surface temperatures as they commute between spinifex tussocks.

Many of the mulga ant species are attracted to seeds with a nutritious elaiosome attached. The seeds are carried back to the nest where the yellow or white ‘reward’ is removed and fed to the larvae. The seed is then discarded outside the nest or more to the point, usefully dispersed, at some distance from the parent plant.

The same habitat is often occupied by a great many different species, some with overlapping needs and others that are active only when the competition is resting, effectively partitioning resources and reducing conflict.

Choosing the hottest time of the day to forage, the high speed furnace ant, Melophorus bagoti is such an ant. This flame coloured species stores honey in the swollen bodies of modified worker ants, a contingency that sustains the colony when food is scarce.

Another storage specialist, the well known honey pot ant, Campanotes inflatus, is better known for the greatly enlarged repletes that are highly prized by Aboriginal people as a rare source of honey in the Australian arid zone.

I know of nests that have been harvested regularly over several decades and remain viable and healthy. People work carefully from the outer margins and take only what they need. Conservation of the nest is guaranteed by a taboo on digging too deeply, the queen is sacrosanct and the story of a small dangerous snake inhabiting the lower centre of the nest is a check on anyone who might be too greedy.

The rich honey contained in the repletes is collected in tiny amounts by worker ants that forage widely through the mulga canopies. Most of the honey dew is collected from lerps, small scale insects that live in clustered lines along narrow branches where they suck on the sap flow of the tree and excrete a clear sweet exudate.

Much smaller quantities of ‘honey dew’ are collected from extra floral nectaries, a single tiny gland located at the base of each mulga phyllode. The accumulated honey is carried back to the nest by worker ants that feed it to the storage repletes thus enabling the colony to survive extended dry periods when food is scarce.

I remember a time in 1986-7 when I worked as a consultant for the ABC Natural History Film unit on the landmark Bicentennial project, The Nature of Australia. Various film crews and contractors passed through Alice Springs and I had the great privilege of working with some notables of the industry. Among them was Densey Clyne and Jim Frazier of Mantis Wildlife films and when I think of ants this dynamic duo springs to mind.

To film the lives of honey pot ants Jim and Densey built artificial nests to enable endless days and nights of macro work in relative comfort. Their behavioural sequences were ground breaking and exquisite.

I could not know at the time how useful the tuition I received from Densey and Jim would prove to be. A couple of years later a BBC film crew arrived with David Attenborough to film sequences for The Trials of Life.

We contacted some families living on homelands north of Alice Springs to see if they were interested in working on the series. Not surprisingly they were great fans of wildlife documentaries and were delighted to accompany us into the mulga.

Several months earlier I’d located a honey ant nest and carefully excavated a section to capture a cohort of workers, and repletes. Following Densey and Jim’s example we built a plaster nest with various embedded conduits and glass panes that allowed back and sidelight to be introduced. Fibre optics gave us a cool lighting source with a measure of adjustment.

This procedure was used several years later for the benefit of an incoming Japanese film crew. I returned to the mulga accompanied by my good friend Peter Wright and we excavated a replete chamber.

After collecting our ants we closed off the damaged chamber with stiff cardboard and backfilled with the intention of bringing the ants back in a week or so.

During this process Peter called me over. He’d inadvertently unearthed some incredibly tiny ants with enlarged repletes, honey ants in miniature if you will. These were new to me and I collected several from the spoil of our diggings but was unable to see much of the damaged nest chambers.

Several months later these tiny specimens were sent preserved in alcohol to a CSIRO entomologist with ant leanings. He replied that the specimens were a bit too desiccated and damaged to be certain but he believed this was probably a new species. How little we know of the subterranean world!

Jim Frazier ended up in the United States working with Panavision to commercialise an ‘infinity’ close up lens he’d invented. The last time I heard from Densey was in 2009 when she rang to request the use of some photographs for her upcoming book entitled All About Ants.

I sent her a couple of images including one of furnace ants with a queen and a mass of males at the nest about to depart on their nuptials. At the time Densey was 86 years old and she still had a couple of books to write before her death in 2019 aged 96.

Her ant book contains some incredible images of behaviour, notably predation of tropical green ant larvae by an ‘armoured’ caterpillar, and nest construction showing worker ants gently clasping pale larval grubs and somehow encouraging them to produce a steady stream of silk. With the care and precision of a cake decorator, worker ants wielding a silk producing grub were sticking together adjacent leaves to form the walls of the canopy nest.

Densey Clyne was a dynamo of Australian natural history. Small in stature and with a hint of her native Welsh accent, Densey presented the disarming persona of a suburban aunt. She was a passionate macro photographer who will be remembered for her lavishly crafted books on insects, notably spiders, butterflies, moths and ants which were mostly directed at children.

She pretty much defined and cornered a market genre best described as wildlife in the suburbs, leaving a legacy of some 36 books authored or co-authored by her. I suspect her list of film credits is no less prolific.

When I decided to include Densey in this ant essay I naturally looked to see what had been written in the form of obituaries. Among them was a personal tribute that surely spoke for the millions of Australian children that were touched by a woman with the tireless energy of an ant and eyes that shone in wonder.