I spotted this poor old possum on the side of the road in Torquay a few weeks ago. And another just yesterday. For tree-dwelling mammals, city-living can be as dangerous as it is lucrative.
In most cities and towns across Australia, the only small native mammals you’re likely to see will be the arboreals – the tree-dwellers. Koalas, possums and gliders can be spotted in even major cities.
One of the reasons arboreal mammals have managed to survive in the urban jungle is because they spend a lot of their time out of harm’s way. High in the canopy they’re safe from cars, cats, dogs and foxes. Interconnected tree branches and overhead power lines mean they can roam unrestricted by fences, making the most of the lush banquet provided by the city’s parks and gardens. In the mean time, their ground-dwelling native counterparts have all but disappeared.
Connectivity is critical to wildlife. Very rarely can an animal get all the resources they need from one place, especially in an urban setting. Food and shelter are spread across suburbs in parks, gardens, and availability varies throughout the year. It can take some careful negotiating to get from nesting tree to feeding tree without setting paw to pavement.
Essentially, urban possums are playing a game of ‘the floor is made of lava’. For those of you who have forgotten one of the best parts of their childhood, let me explain. When the lounge room floor is made of lava, you have to leap from couch to couch and clamber over the coffee table to avoid touching the floor. Because it’s made of lava. If you’re lucky, a well placed ‘stepping-stone’ cushion can launch you to the safety of the doormat on the other side of the room. Last one standing wins.
Unfortunately the aerial highway of tree branches, rooftops and power lines has its limits. Inevitably, when gaps are large and trees are sparse, animals will have to move along the ground. Koalas have it particularly tough. Their size and burly bodies aren’t suited to the acrobatics required to tiptoe across electric wires. So when they want to move to a new feeding tree, the only way is down.
This is where they are at their most vulnerable. Feisty as they are, a koala or possum is no match for the average family dog or marauding fox. And certainly no match for a car. Some even get lost and end up wandering into places they really don’t belong (like this koala here).
So, how can we help make sure our urban tree-dwellers don’t meet a gristly end? Keeping your pets contained is a good first step (cats inside at night and dogs in yards), particularly if you live near a nature reserve or local park. If you enjoy having wildlife in your yard, look into providing safe nesting sites (other than inside your roof) or feeding trees. At the bigger end of the scale, wildlife crossings like these rope bridges or underpasses can link valuable habitat patches and keeping animals off roads.
Possums in urban areas can be a contentious issue and a discussion that deserves it’s own post later down the line. But let’s all agree that whether or not you like an animal, a brutal death on the nature strip is not a pleasant way to go.
Further reading
van der Ree and McCarthy 2005 – A scientific paper describing the lack of small terrestrial mammals from the Greater Melbourne area
More about wildlife crossings for arboreal animals here and here
Koala Cul-de-sac? An article in The Conversation about the plight of urban koalas
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