Daylight saving time can decrease the frequency of wildlife-vehicle collisions
Ellis, WA, FitzGibbon, SI, Barth, BJ, Niehaus, AC, David, GK, Taylor, BD, Matsushige, H, Melzer, A, Bercovitch, FB, Carrick, F, Jones, DN, Dexter, C, Gillett, A, Predavec, M, Lunney, D & Wilson, RS 2016, Biology Letters, vol. 12, 20160632.
This study explores the benefits of implementing daylight saving time (DST) in Queensland to alter the timing of commuter traffic relative to nocturnal animal movement. Wild koalas in southeast Queensland were tracked and road crossings monitored then applied to a mathematical model. The model showed that DST could decrease collision rates by 8% on weekdays and 11% on weekends.
Traffic flows at monitored sites varied from 1600 to 3000 vehicles per hour, with peak flows at 7-8 am and 3-5 pm on weekdays and 11am on weekends. Wildlife-vehicle collisions have been consistently reported to peak at dusk, with a greater number of collisions in months with more hours of darkness. More than 300 koalas are killed by vehicles each year in southeast Queensland, and it is a major cause of their population decline. Previous studies have found koalas spend 10% of their time on the ground, with very little of it spent crossing roads. Forty-five road crossings by five koalas were recorded in this study, with 49% occurring during twilight (4-8 pm) and 64% occurring during late evening twilight or darkness (6 pm – 4 am). The koalas became most active at 4 pm, overlapping significantly with peak traffic flow on weekdays. By assuming collision rates are proportional to the amount of traffic and probability of a koala moving, a one-hour shift in commuter traffic peaks as a result of DST would reduce the overlap between koala movement and afternoon traffic maximums. The weekday collision risk would decrease less relative to the weekend due to the resulting increased overlap during the morning commute period.
Through understanding the overlap between koala movement and traffic flow, it can be seen that adopting DST could have positive conservation effects on koala populations in southeast Queensland by reducing koala mortality on roads.
Summarised by Laura Wait
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