Urban

Science Short: The Black Swans of Albert Park

Wild Melbourne’s Science Short series is a collection of short video documentaries showcasing the wonderful research being done in Victoria. Each episode features a different scientist or research group, opening up the world of environmental research for the public to see. 

In this Science Short, Wild Melbourne venture to Albert Park Lake near the Melbourne CBD to follow the University of Melbourne Black Swan Research Group. Headed by the University of Melbourne’s Head of BioSciences, Raoul Moulder, the BSRG has been researching the black swan population at Albert Park for over a decade.

Raoul, along with Dr John Lesku from La Trobe University, is supervising PhD student Anne Aulsebrook as she investigates the effect that artificial lighting in urban areas is having on the biology of the swans. Artificial lights, such as street lamps, headlights and signs, are known to change how animals behave and respond to more natural cues.

Behaving in an Urban World

This is a guest post by Monash University PhD student Will Sowersby. 

You may have noticed that the world around you is changing. In fact, it is doing so at an unprecedented pace. Today, half of the world’s population live in cities and by 2050, that figure will be over 70%. In evolutionary terms, this rate of urban development represents a radical ecological upheaval. It is the sort of change that, in the past, generally occurred over geological time, not within generations. The process of urbanization often results in a loss of biodiversity due to the destruction and fragmentation of habitat, as well as the exposure of animals to artificial stimulations and pollutants. In many ways, we might expect such radical changes to leave our cities totally devoid of life, or only inhabited by the few hardiest species. Instead, more and more animals appear to be adjusting to and exploiting life on the streets. Peregrine falcons are nesting in skyscrapers instead of towering trees and crows are using passing cars as nut-crackers.

How have these species adapted? Well, the first way an animal responds to changes in its environment is by altering its behaviour. In this regard, the ability to adjust behaviour to changes in the environment can mean the difference between a population surviving and going extinct. Recently, the importance of studying animal behaviour in urban settings has become a hot topic in behavioural ecology: the area of science that explores how behaviour shapes – and is shaped by – the environment. By studying the behaviour of animals in urban areas, we can further our understanding of why some species have flourished, why others have not, and what measures we can take to help wildlife live in our cities and decrease biodiversity loss in urban areas.

So what allows some species to flourish in urban environments, while others fail? Some may simply have an inherent set of behaviours and life history traits that make them ‘pre-adapted’ to city life. Often, such animals have also benefited because urban settings have eliminated competitors and provided additional food sources. In Melbourne, for example, aggressive social birds such as noisy miners have flourished, often to the detriment of smaller, native bird species. Similarly, most Melbournians will be familiar with the grunts and hisses of the brushtail possum, an opportunistic marsupial that has benefited from feeding on our gardens, inhabiting our rooves and even taking a free feed from well-meaning residents.

The noisy miner is one of many bird species flourishing in urban environments.  Photo: Emma Walsh

The noisy miner is one of many bird species flourishing in urban environments. Photo: Emma Walsh

Many of the animals we now see reappearing in our cities and suburbs differ greatly from their bush and rural counterparts. For example, many urban populations – including birds, lizards and mammals – are significantly bolder than non-urban animals. Bolder animals may be better able to cope with human activity, less likely to retreat from threats, and quicker to exploit new food sources. Furthermore, urban animals also get less stressed. That is, they release less stress hormones than non-urban animals, which would be beneficial for living in a highly stimulating and chaotic environment. Remarkably, some animals have even begun to learn the rhythms of our cities, such as watching for traffic and crossing roads when traffic lights are red.

We have only recently become aware that many animals exhibit consistent “personalities”, or more accurately, behavioural types. Certain behavioural types correlate within an individual (e.g. aggressiveness and boldness) to form what is called a ‘behavioural syndrome’. Behavioural syndromes are considered to be largely inflexible across contexts and are likely to be heritable. Therefore, individuals inhabiting urban environments may have a set of inherent behaviours that have allowed them to more readily adjust. This means that other individuals in a population may not be able to demonstrate appropriate behaviours in urban environments. Consequently, urban animal populations may have a lower diversity of behavioural types compared to non-urban populations, and a lack of diversity is rarely (if ever!) a good thing.

The common brushtail possum is a familiar sight for many in suburban Melbourne.  Photo: Dr Carlo Kopp

The common brushtail possum is a familiar sight for many in suburban Melbourne. Photo: Dr Carlo Kopp

Artificial light has well known effects on animal behaviour (refer to a recent Wild Melbourne post by Anne Aulsebrook) and so does anthropogenic noise. Many frog species around Melbourne are being drowned out by traffic noise, impacting the chances of males attracting mates. One species, the southern brown tree frog, is offsetting this by raising the pitch of its calls in noisy environments, so that males can be heard from further away. Noise pollution is also forcing urban birds to adjust their vocal communications or risk going unheard. Urban silvereyes are much louder than their rural counterparts, while urban noisy miners can even adjust the volume of their calls depending on whether they are near busy or quiet roads. 

Chemical pollutants that are getting into the environment are also having a dramatic effect on the behaviour of wildlife. For example, hormones used in agriculture in Australia, which leach into our waterways, can alter the mating behaviour and morphology of freshwater fish. Furthermore, chemicals used in the human female contraceptive pill are the likely cause of feminization in fish, which has a significant impact on their ability to breed.

Growling grass frogs are one species that may be suffering due to traffic noise.  Photo: Peter Robertson

Growling grass frogs are one species that may be suffering due to traffic noise. Photo: Peter Robertson

How can we use our knowledge of animal behaviour to minimise the impacts of urbanisation and to encourage animals to return to our urban spaces? We should firstly feel encouraged by the fact that we can coexist with wildlife. By offering native animals a wide choice of native vegetation and large, undeveloped areas in our cities, we can increase both the diversity of species and the diversity of individuals within species in our urban spaces. By knowing how and when animals move through the landscape, we can create safer passageways for them. Already, road-crossing structures are allowing some of Victoria’s rare arboreal marsupials to safely cross highways, while crossing structures are helping red crabs on Christmas Island to make their annual migration. Elsewhere, cities are turning the lights off in large buildings at night, so that migratory birds are not distracted as they fly past. We could do the same here in Melbourne (at key times during the year), along with implementing stricter pollution controls (particularly in sewage and wastewater treatment plants), lowering noise pollution, decreasing vegetation clearance, not feeding wild animals and keeping cats inside (particularly at night). Ultimately, a city shared with wildlife is not only healthier for us, but also far more interesting. By beginning to understand the creatures around us, we can make sure our cities are not only home for us, but for them too.

Banner photo courtesy of Anne Aulsebrook.

Urban Wildlife and Responsible Cat Ownership

If I were a feral cat, I would steadily be getting more and more concerned about my wellbeing. In order to halt the decimation of our native wildlife, the Federal Government has recently released the Threatened Species Strategy. Part of this strategy is a pledge to humanely remove two million free-living feral cats from wild areas across the nation.

For many, this is a long-awaited development in our fight against extinction. Cats were introduced to Australia with the arrival of European settlement. Since their introduction, Australia has lost 29 native mammal species, with feral cats implicated as one of the main causes for the extinction of 20 of them. Furthermore, the Action Plan for Australian Mammals, released in June 2014, concluded that 55 species of native wildlife are threatened and require urgent conservation action.

If you’re a cat owner like me, you may be thinking: “So what? My cat isn’t feral, she hardly EVER brings anything home, and she is far too lovely to be categorised as a ferocious predator!” But you would be wrong (I’m sorry, I know it hurts to hear it).

Domestic cats ( Felis catus ) are a major threat to Australian mammals, birds, reptiles and amphibians. Photo: Billy Geary

Domestic cats (Felis catus) are a major threat to Australian mammals, birds, reptiles and amphibians. Photo: Billy Geary

While research on the impact of domestic cats on native wildlife is scarce compared to that of feral cats, it suggests that domestic and stray cats do negatively impact many of our native species. For example, domestic cats have been implicated in the decline of the Superb Lyrebird in Sherbrooke Forest, and in the decline of the Eastern Barred Bandicoot in south-western Victoria. In the case of the bandicoot, cats were responsible for at least 42 percent of deaths in juveniles. Other studies have found that 50 to 80 percent of cats partake in hunting activities, but that the cats only brought between one third and one half of their prey items home.

I’ll admit it, I don’t like to think of my moggy as a parrot-eating, spinebill-chasing huntress, but our urban wildlife is too important to ignore this problem any longer.

In recent years, many councils have moved to reduce the impact of pet cats on native wildlife in their municipalities by imposing cat curfews. In the City of Wyndham in Melbourne’s north-west, cats must remain on their owner’s properties between the hours of 10pm and 6am, and between 8pm and 6am in the City of Whitehorse in Melbourne's east. The Yarra Ranges Council has gone a step further, requiring that cats must stay on their owner’s property at all times.

It's hard to believe that my little fluff-ball is contributing to the loss of our urban wildlife, but it is something that I must accept responsibility for. Photo: Emma Walsh 

It's hard to believe that my little fluff-ball is contributing to the loss of our urban wildlife, but it is something that I must accept responsibility for. Photo: Emma Walsh 

So what can you do to limit your feline friend’s impact on our native birds, mammals, reptiles and frogs? For starters, you can have your moggy desexed. This won't stop your cat from hunting, but it will eliminate any chance of it contributing to the proliferation of feral and stray cat populations. This will also help to reduce the number of dumped and unwanted cats that overrun animal shelters every year. If you are looking for a more direct approach, there are things like brightly coloured cat bibs which bring the cat to the prey’s attention, or other apron-like collar attachments which interfere with paw-eye coordination to reduce the wearer’s chance of a successful pounce. Finally, you can keep your cat indoors as much as possible. This is the most effective way of protecting our fauna, and also limits your cat’s chances of being injured in a road accident or catfight.

It’s difficult to acknowledge that your furry friend may be feasting on native animals behind your back, but acceptance is the first step to solving the problem. By making a few calculated commitments towards limiting your felines take-away habits, you can help to halt the decline of our urban wildlife. 

Melbourne's Green Laneways: Back Creek Reserve & the Importance of Urban Green Spaces

Just how important are green spaces in urban environments? What animals use these spaces? How valuable are these spaces to people? With increasing urbanisation occurring across Australia and indeed the world, it is becoming more and more important to answer these questions so that these small tastes of nature can remain as cities expand.

The team at Wild Melbourne has pondered these questions for some time, so we set out to find the answer. Using Back Creek Reserve in Camberwell as a case study, we set out to find just how important urban green spaces are to maintaining biodiversity, as well as keeping people in touch with nature.  To do this, we spent a couple of weekends at the reserve documenting every species of animal we saw or heard, as well as chatting to passers-by to find out their feelings towards the space. Read on to see what we found: 

Mammals
Chances are, if you live in a remotely leafy suburb of Melbourne, you’re likely to be familiar with two species of marsupial: the common brushtail possum (Trichosurus vulpecula) and the common ringtail possum (Pseudocheirus peregrinus). Green spaces such as Back Creek are havens for possums, as they provide plenty of cover from predators such as powerful owls, and food resources such as flowering native plants.

Common RIngTail possums are found throughout Melbourne's Green spaces (Photo: Emma Walsh)

Common RIngTail possums are found throughout Melbourne's Green spaces (Photo: Emma Walsh)

Whilst Melbournians are quite familiar with a few of the mammals that call our city home, there are also a few that fly under the radar, so to speak. These are the winged variety of mammal: flying foxes and microbats. Back Creek appears to be a stopover for grey-headed flying foxes (Pteropus poliocephalus) on their evening journey, whilst the space appears to be home to at least one microbat: the white-striped freetail bat (Tadara australis). This tiny bat is one of the only microbat species whose ecolocation is audible to humans, and can be heard in most parks around Melbourne as they search for food.  

The kookaburra (Photo: Cathy CavAllo)

The kookaburra (Photo: Cathy CavAllo)

Birds
The birdlife spotted along Back Creek was quite diverse. The 22 species recorded fell into five ecologically distinct groups. Amongst the carnivores were the grey butcherbird (Cracticus torquatus) and the laughing kookaburra (Dacelo novaeguineae). These two species often feed on insects, but also feed on small lizards and other vertebrates. To our surprise, a collared sparrowhawk (Accipiter cirrocephalus) was also spotted. This species feeds mainly on small birds, which shelter in green spaces such as Back Creek. The nocturnal tawny frogmouth (Podargus strigoides) were also observed. 

Several insectivorous passerine species were recorded, including brown thornbills (Acanthiza pusilla), willy wagtails (Rhipidura leucophrys), grey fantails (Rhipidura abiscapa), silvereyes (Zosterops lateralis) and white-browed scrubwrens (Sericornis frontalis). These species are attracted by the food sources provided by urban parks, and require shrubs and bushes for shelter in order to hide from predators.

Several species important for pollen dispersal were recorded, including both parrots and honeyeaters. Ecologically-important species such as rainbow lorikeets (Trichyglossis haematodus) and galahs (Cacatua roseicapilla) were seen frequently. Honeyeaters observed included eastern spinebills (Acanthorhychus tenuirostris), red wattlebirds (Anthchaera carunculata) and noisy miners (Manorina melanocephala). These species feed on the nectar produced by flowers, and in doing so help to disperse pollen and therefore influence the reproduction of various plant species.

Other species observed include the Pacific black duck, and omnivorous corvids such as the Australian magpie (Gymnorhina tibicen), the little raven (Curvus mellori) and the pied currawong (Strepera graculina). Several invasive species, such as spotted turtledoves (Streptopelia chinensis), Indian mynas (Acridotheres tristis), common starlings (Sturnus vulgaris) and common blackbirds (Turdus merula) were also observed.

The noisy Minor is a common sight in many parks and green spaces (Photo: Emma Walsh)

The noisy Minor is a common sight in many parks and green spaces (Photo: Emma Walsh)

Amphibians
We also recorded two species of frog calling at various times: the common brown tree frog (Litora ewingi) and the pobblebonk frog (Limnodynastes dumerilii). Green spaces with running water such as Back Creek Reserve can provide a rare opportunity for frogs to persist in urban areas. Frogs are also fantastic indicators of water health, which suggests that Back Creek must be in good condition to support the observed frog community.

The People
The benefits of nature extend beyond aesthetics and the conservation of wildlife. Numerous studies have shown that interaction with nature can vastly improve mental and physical health. Living next to green space has been shown to lower stress and anxiety, and even improve concentration in children. But can we experience this same effect in what appears to be just a small sliver of wilderness in the heart of suburban Melbourne? The overall consensus of up to 76 people interviewed along the Back Creek trail was that the area offered solace, was quite relaxing and provided a much-welcomed escape from the urban environment and their daily stressors.

The continued success of Back Creek is also a shining example of community involvement. The restoration and maintenance of the area is a source of pride for locals; many have contributed to the wellbeing of the environment, the fruits of their labour clearly extending to the happiness of the broader community. Back Creek’s ability to provide an escape amidst the hustle-and-bustle and pressures of modern life is testament to the power of just one of Melbourne's many 'green laneways'.

Overall, we recorded 28 species of fauna across just two weekends of surveys at one urban green space in the middle of Melbourne. This, along with the feedback from people using the park, is a strong indicator of just how important green spaces can be for both biodiversity and our own wellbeing. It is therefore critically important that we look after our green spaces, as they are a vital part of a healthy community - for both humans and other animals alike.