The former Queensland premier Joh Bjelke-Petersen famously argued that daylight saving time (DST) would confuse milking cows, which it might, but only because it changes human behaviour.
All animals have circadian rhythms, but only humans have DST. We flip time forwards and backwards, often with little idea of how that can affect other species.
On Sunday morning, when most states put the clock back by an hour, it will shift the peak commute home closer to dusk, when animals like kangaroos are more active.
Cars – with their lights and noise, and the danger they pose – can affect insects, birds and wildlife. An increase in light pollution as night falls earlier and lights come on also impacts wildlife in urban areas.
University of Melbourne evolution and animal behaviour professor Therésa Jones says all species – even plankton – have circadian rhythms. “They’re all working on a clock but it’s not a physical clock, it’s set by the sun.”
She is researching how human activities intersect with insects’ and birds’ collective noisemaking using automatic recorders to create audio soundscapes.
Sign up for the Breaking News Australia email“[With] daylight saving, we start shifting our cars and our daily routine more into the zone of animals, their sunset, sunrise period … suddenly there are cars when all the dusk choruses are happening,” she says.
“They’re chorussing, or making noise, or going to sleep, or waking up … then humans come and throw lights into a space that was dark. We’re active in the day, we make our way home at night and when we change the clocks, it suddenly changes.”
Earlier research by Jones and colleagues found increased amounts of artificial light at night affected crickets’ mating choices, but not their courtship calls.
Artificial light at night, which increases when daylight saving ends, is a profound change in urban ecosystems.
The NRMA has also warned that the longer nights of winter overall mean more collisions, with the most insurance claims being made in July.
“Species that would be of obvious concern would be kangaroos and wallabies, that are often quite active both in the morning and in the afternoon around dusk, so any increased traffic around the time when they’re most active can create potential issues with road accidents,” Deakin University wildlife ecology and conservation professor Euan Ritchie says.
“Wombats, any of those that come out around dawn and dusk.”
That also means having DST could be good for wildlife.
A 2016 study found that if Queensland were to reintroduce daylight saving (they voted to get rid of it at a referendum in 1992) it would save koalas.
University of Queensland researchers said if it was still light when commuters drove home, fewer would be hit and killed by cars.
But it’s a mixed result when the clocks go forward.
“When DST begins, it actually affects the morning [bird and insect] chorus, which is often the mating chorus,” Jones says.
“Traffic noise … can also mask the singing, which can be really important for roosting birds, for socialisation.”
And any change that affects humans can affect their pets. Plenty of owners have posted videos of confused dogs begging for their dinner to social media.
According to the American Kennel Club, any change in routine can affect these creatures of habit, so they can be unsettled by sudden changes to when they get up, when they walk and when they eat.
But that’s nothing to do with the clocks, it’s them responding to us. According to National Geographic, dogs have circadian rhythms that can be affected by lights, but that they are “very, very influenced by their human companions”.
In Australia, DST was adopted as a wartime measure to save fuel by reducing the need for artificial lighting.
The idea, though, is widely credited to a New Zealand entomologist called George Hudson. In the 1890s he proposed a two-hour time shift – he wanted more time in the evenings to look for bugs.
