Our cities continue to grow. All governments, developers and most economists continue to promote this as a good thing but is it good for all? There are plenty of first-degree losers suffering under this relentless onslaught of greenfield development. Habitat removal continues to be the most obvious and significant threatening process affecting wildlife in Australia today. Our iconic Koala despite its charisma continues to lose habitat to purple brick boxes and the pine plantations grown to provide building materials. It is not uncommon today that newly developed urban subdivisions reduce the grazing resources of kangaroos to levels where ‘humane’ culls are invoked. But what about those animals and plants that appear to persist in urbanised landscapes? Have they managed to avoid the consequences of a highly modified landscape? Certainly, in some cases populations of native fauna seem to be doing very nicely thankyou very much. In this rant, I review a couple of those apparent survivors and explore the processes and drivers that might have a hand in their success. I also ask if sometimes there can be too much of a good thing, in the context of survivors and their success.

Chryptocheilus wasp dragging a paralysed Huntsman spider (Sparassidae family) over my suburban driveway. Both animals appear to persist in well-established urban environments.

Our Best Intentions

Green roofs, green walls, carbon neutral, constructed wetlands, constructed hollows, nest boxes, bee hotels, bird baths, street tree planting, green spaces, re-wilded gardens, and wildlife corridors are all attempts to make our ever-expanding built environment more nature friendly or at least less antagonistic to members of the natural world. Are these and other endeavours successful, futile or misplaced efforts to assuage our discomfort with the consequences of our societal impacts? Probably all of the above. It is undeniable that our engineered landscape is a bane to many native organisms but it is also an apparent boon to some. Let’s look at the status of a couple of high-profile survivors and explore the actions or processes that may have led to their current double edged success stories.

The Rainbow Lorikeet

Status

The populations of Trichoglossus haematodus look to be growing across Australian cities, including those such as Perth, where historically it did not occur. It is now considered by some ornithologists as posing a significant threat in Tasmania to the critically endangered Swift parrot. So, what has happened?

Certainly, during my childhood in the sixties and seventies, one would have to travel from Sydney to Currumbin Wildlife Sanctuary to be sure to see these gregarious birds. Now, in my Sydney backyard, I find myself occasionally barking at these birds to shut-up for a bit, just to let me think. In fact, this may be one of the most observed birds on the east coast of Australia. In the last few years, it has been one of the most counted bird species in BirdLife Australia’s Backyard Bird Count.

What has changed?

This is a flocking bird that roosts in large groups, drinks nectar, is a feeding generalist, willing to also consume seed and insects and is pretty feisty if not downright belligerent. Yep, it’s a bird with attitude that likes to party. This bird opts for the bright lights of a main street to roost at night and these artificial lights appear to have a similar effect on the birds as they do on humans. They stay awake much longer into the night. This gives them more hours per day to find and court a mate, within an environment that is less amenable to their natural predators. Snakes and Owls being less likely to frequent such venues. Survivorship probably has increased. Then, courting sorted and with that attitude, they find a nest site, artificial nest box or tree hollow, they aren’t fussy and proceed to evict the current tenant, bird or otherwise. Rainbows are relentless in misappropriating hollows. Reproduction rate probably has increased. Then there is range extension. These birds naturally occur in a variety of woodland and forest types, so they are wired as generalists. They don’t need the bright lights, but town centres do boost their numbers and the less sedentary, adventurous birds of these expanded populations do okay when they encounter most types of bushland. They even enjoy the seeds of pinecones, so pine plantations support their range expansion. Of course, there is also direct human involvement as well, with accidental or intentional release of caged birds. There are no obvious barriers to their range expansion today. Another factor that has changed to the advantage of the Rainbow Lorikeet (and others) is the composition of gardens. When I was a kid. Sydney backyards were all exotic plantings with some endemic trees relegated to roadside nature strips and parks. This was followed by a horticultural renaissance that embraced the native. Actually, to be more correct, it embraced the Grevillia, Leptospermum and Callistemon. Native nectar bearing shrubbery replaced the Oleander, Hibiscus and Abelia. High energy drinks were now readily on tap across the urban landscape and I have to admit our own 40 year old backyard Honey Gem is rarely devoid of Lorikeets, while the Lemon scented gums on the verge above the streetlights, play host to a noisy roosting population most nights.

Consequences

Is it a bad thing and are they here to stay? I believe over 300 species of animal use tree hollows in Australia. The less aggressive such as Rosellas, other parrots and some gliders are being physically evicted by home invaders such as the Rainbow Lorikeets. I can’t see the abundance and expansion of Rainbows in this context as good at all. Whether these expanded populations are sustained may depend on how much of the necessary food and nesting resources are lost to high density urban renewal over time. I suspect that these birds will always have a place in the low and medium density suburbs and leave the concrete jungles to the feral pigeons.

The Noisy Miner

Status

Like the Rainbow Lorikeet, the populations of Manorina melanocephala look to be growing across Eastern Australian cities and towns. In fact, though not a Lorikeet, there are many similarities. It occurs in large cooperative colonies, is a nectar feeder that also eats insects and seed. The suburban garden makeover that introduced sugar rich resources has also benefitted this bird but so has the green space planning of urban East Australia. Noisy Miners naturally occur in a range of wooded habitats but is most abundant along woodland and forest edges. It’s advantaged by interzones, boundaries between open spaces and tree dominated environments and our ever-expanding population centres, roads and farms continue to fragment and create new edges. Our modification of the broader landscape and our creation/retention of parks and green spaces with trees within urban settings suit the needs of Noisy Miners perfectly.

Consequences

Though not hell bent on evicting other birds from tree hollows, it is broader in it’s aggression by relentlessly harassing other birds in or on the boundaries of its territory. Size is no obstacle. In my own backyard I am at risk of being swooped and clacked at, not by the last few Magpies yet to be evicted but by these aggressive grey plumed mobsters. Also, like the Rainbow, these birds are big vocalisers having a range of calls including ones for danger and ‘let’s attack’.

Small and medium sized birds, native or feral are no match for the team effort put in by these birds. The introduced Common or Indian Myna, that has prompted regional communities to engage in trapping programs is a pushover for the coordinated bullying of the Noisy Miner.

The Rainbow Lorikeet and the Noisy Miner both need access to trees for roosting and nesting which suggests the combination of low and medium density housing in reasonable proximity to wooded landscapes will continue to support the abundance and spread of these birds. Interestingly, in my suburb where medium density housing with nil green-space is edging out Californian bungalows and backyards, the Rainbows have recently introduced a zero tolerance policy in regard to sharing nectar trees with the Noisy Miners. Resource limitation may be stimulating further aggressive behaviour.

It’s great to have some Australian animals surviving the onslaught of urban expansion but in the case of these two birds, many of our suburban backyards are far less diverse in bird species as a direct consequence of the success of these survivors. It’s not a silent Spring but it is a raucous one with the songbirds kicked out by the less melodious birds.

My own backyard, remote from bush for over 50 years, still hosted Wagtails, Pardalotes, Silvereyes, Peewees, Barn owls, Shrike thrushes, Cuckoos, Magpies, King parrots, Currawongs, Cockatoos, Doves, Butcherbirds, Kookaburras, Lapwings, Wrens and the odd Robin as well as Sparrows, Bulbuls, Starlings and Mynas in years past. Today, apart from Rainbows and Miners in abundance we see the odd Currawong and less commonly a Magpie. We hear Koels, Channel Bills and Lapwings passing us by. Of course other disturbance factors have played a role in the loss of some of these. Insecticides, rodenticides, the loss of native grasses, berries and protective understory have all had a part but I keep asking myself. “Should I chop down the Honey gem, will it make a difference now?”

Urban Landscapes: Survival of the Fittest or Fit for the Survivalists?