You’ve felt it, haven’t you? The days are getting warmer, there is still some light left in the sky when you get home of an evening, and you’re either really excited about the upcoming footy finals series or shifting hope to your team’s prospects next year. Yep, spring is definitely just around the corner. Already I've seen Australian magpies and noisy miners gathering nesting material, and witnessed male common blackbirds staking their territorial claims as they chase each other around the backyard on an endless merry-go-round.
For many of us, spring is our favourite season. The warmer weather stimulates us to get outdoors after a winter spent in front of the heater, and our explorations are rewarded with spectacular floral displays and a hive of activity among the bird community. Spring is the peak breeding season for most of Victoria’s birds, meaning that many usually skulking species belie their presence by calling loudly to attract mates and defend territories.
In a few weeks, all of this activity translates into many freshly-hatched young. The first few months of life are often the most dangerous for many animals; they have to learn quickly and become proficient at all the skills they will need to successfully reach adulthood. Evolution has equipped many species with remarkable instincts for survival during this treacherous period, yet the rapid pace of human-caused environmental change has presented new challenges that instinct has yet to adequately address.
We have become increasingly dependent on roads for transport and freight, and for species that have been around for thousands of years, the emergence of a vast road network has been a relatively recent phenomenon, giving them little time to adapt to the threats it poses. For a young bird, freshly out of the nest and learning the finer arts of flight, the sight of a car hurtling along at 100 km/h must be puzzling. Indeed, in studies estimating mortality of native birds on our roads, there is often a peak in the rate of roadkill during spring and early summer, and unfortunately, those killed are mainly young birds. It seems that their naivety towards cars means they either do not perceive a fast-approaching car as a threat until it is too late, lack the skills required to make evasive manoeuvres, or make poor decisions when trying to avoid being collided with.
The warmer months are also the time when many of our reptiles become more active after emerging from their winter brumation (akin to hibernation). Being ectothermic (commonly referred to as cold-blooded), they can often be found in a sunny spot so that they can soak up the warmth they need to be active. To a reptile, roads are seemingly the perfect place to do this because they lack trees and shrubs which would cast shade, and the black road surface is an effective absorber of the sun’s energy – I’m sure you can remember being caught barefoot on bitumen and having to dash from shade patch to sweet, relieving shade patch.
On a cold spring morning, a reptile basking on a road may be slower to take evasive action at the approach of a car because their body temperature has yet to rise to a level sufficient for rapid movement. Consequently, they are more likely to be hit. The warmer months are also when our reptiles are out looking for mates and so may be more likely to cross a road while on this search. The attractiveness of roads as basking sites and the compulsion to cross roads in search of mates combines to make the coming months a period of carnage for our reptiles.
Frogs, too, may venture out of their wetland homes on warm, rainy evenings in search of mates or habitat made newly available by the rains. The road toll for these small animals can be huge, and the studies that have looked at amphibians killed on our roads likely underestimate the true number because their soft bodies rapidly become difficult to find.
Having described how our roads will become a death trap for many animals in the coming months, I bet you’re now thinking that I’m going to tell you that you must drive at only 20 km/h wherever you go. However, I realise that it is impractical for us to make a behavioural change such as this, even if slower travelling speeds would result in fewer wildlife deaths. Instead, I ask you to be considerate; if you see a group of birds on the road ahead or a dark shape that may be either a shadow or a basking bearded dragon, be prepared to slow down (if safe to do so) to give these potentially naïve or slow individuals extra time to make their dash for safety. Slowing down for just a few seconds may mean that the animal lives for many more years, and awareness is all it takes for you to make this positive change.
Rowan is a Monash University PhD graduate and now works there as an ecologist. His research interests are broad, spanning seabird foraging ecology to plant invasions. When not in his office, he will most likely be in a woodland with binoculars around his neck and camera in hand.
You can find him on Twitter at @roamingmoth
Banner image of an eastern bearded dragon courtesy of Rowan Mott.