It was in the pre-dawn hours about eight years ago that I first saw one, a magnificent stag with antlers big enough to hang a bloom of berets. I’d seen deer before, of course, but not here, in my mother’s suburban Wollongong backyard, mere metres from her kitchen window. Was I dreaming?

“They’re everywhere,” Mum told me over breakfast in a tone familiar to anyone who’s seen Go Back to Where You Came From. “And they’re destroying my garden, everyone’s gardens.”

Though my mother’s house, the one in which I grew up, is just 5 kilometres from Wollongong’s CBD, its sloping backyard falls into a bush gully, or “the creek” as we call it. As kids, my siblings and I used to roll down it, past the cultivated foliage, past the yard-framing eucalypts and through the long grass until we’d plunge into what seemed like wilderness.

Away from the house, but still within yelling distance, we made cubbies in trees, strafed the undergrowth with rocks, and blazed trails though immense thickets of lantana.

Down at the creek we snaffled cicadas, frightened cockatoos, skinks, blue-tongues and snakes, and played host to ticks and leeches. Sometimes we’d stumble upon a porno magazine, half-covered by leaf litter and ruined by the elements but intact enough to linger over. To this day I can’t take a bushwalk without remembering those voluptuous young women and their indigenous shrubbery.

But there were no deer back then, so that evening I went exploring.

Wollongong, it transpired, had been infiltrated – some might say overrun – by deer of the rusa species. In 1906, seven of them were brought from South-East Asia to inhabit an enclosure within the Royal National Park 40 kilometres north of central Wollongong. The deer soon escaped their corral and gradually widened their habitat. In the early 2000s they began marching like colonisers south along the Illawarra escarpment. Under pressure from the dominant stags, the inferior males and their kin were forced even further afield – particularly in the winter months, “rutting season”. So they sought out sustenance and shelter in the rich gardens, lawns and reserves of Wollongong’s northern suburbs, and those that lie on the ocean-facing slopes of Mount Keira, Mount Kembla and the grandly named lump of Mount Nebo.

And from there, a splinter group of these deer clipped along the corridors of chlorophyll and over the suburban streets that momentarily interrupted their flow. All the way to the creek behind Mum’s house.

After I passed by her trampled ferns and garden beds, and young trees crudely pruned halfway up, I found a herd of them: stags, does and fawns. They were standing close to hollows they’d carved out of the lantana, aptly enough an invasive species imported for ornamental purposes. I stood watching these rust-coloured deer, about a dozen in total, and in turn they considered me. I hadn’t lived in Wollongong for 20 years, so who exactly was the interloper here?

Lithe, graceful and, of course, doe-eyed, Wollongong’s deer have nevertheless attained pest status, estimates of their number varying between 2500 and 4000. As well as testing the patience of local gardeners, they are considered a biosecurity risk “due to their potential to carry weeds and transmit disease”, as a city council factsheet puts it.

Given deer can weigh up to 150 kilograms they’re also a threat to human life, mainly due to their ignorance of road etiquette – something they share with the P-platers who roar up Mum’s street oblivious to anything that might be over the crest. Earlier this year, University of Wollongong maintenance staff claimed to have seen about 100 deer strolling along residential Robsons Road in Keiraville early one morning. Hundreds of vehicular near misses, dozens of collisions and two road deaths have been linked to deer in the Illawarra since 2007.

Over the past four years, professional and licensed recreational hunters have shot about 1400 deer as part of a council-funded program. Others have been culled by the NSW National Parks and Wildlife Service, their carcasses fed to the Sumatran tigers at Mogo Zoo, south of Batemans Bay. But the problem has barely been managed, let alone solved.

Some fed-up residents have taken matters into their own hands, and not just by erecting fences and installing motion-sensitive sprinklers. Many deer have been illegally shot, some dangerously close to suburban homes. Deer have been beheaded, their carcasses left to rot on sporting fields or private land. It’s impossible to say how many of these killings have been carried out by illegal hunters looking for a trophy to stick in their poolroom.

These days, the deer still get into Mum’s garden, either by making mighty parabolic leaps over her makeshift fence or by trotting down her front driveway and around the back steps, like unwanted visitors taking liberties.

On a recent visit I saw that the council had bulldozed swathes of lantana around the creek, “in the hope of forcing the deer back to the escarpment”, my mother explained. “I haven’t seen any for a few weeks,” she added optimistically.

Hours later, as I stood at her kitchen window, I peered into the garden and saw in the fading light a doe and a fawn moseying insouciantly across the neighbour’s backyard. To me, it was a beautiful sight. I didn’t have the heart to tell her.