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The impact of roadkill is “much more shocking” than previously thought, the researchers warned, based on an analysis of animal populations around the world.
Collisions with vehicles on the road were found to be the most common cause of death in almost a third (28%) of the 150 animal populations studied – ahead of disease, hunting and predation.
The researchers said their findings, recently published in the journal Biological Reviews, indicate that some mammal populations may thus be reaching a “tipping point” – a critical threshold which, once crossed, could become irreversible.
Lead researcher Lauren Moore, from Nottingham Trent University’s School of Animal, Rural and Environmental Sciences, said: ‘The scale of road fatalities is far more shocking than we previously imagined and it is clear that she is involved in a possible tipping point for some. wild populations.
“While at times the raw number of animals killed may seem relatively low, road kills can, directly and indirectly, contribute to mortality rates that exceed reproductive rates, making populations vulnerable.”
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Ms Moore and her colleagues reviewed 83 studies of mammalian deaths in 69 species.
Of the 83 studies, two in the UK found that 29% of skunk deaths and 25% of hedgehog deaths were due to roads, while 9% of the hedgehog population was killed on roads.
Ms Moore said skunk research has shown that time, money and effort spent on rehabilitating injured or sick creatures is ‘undone by roads’ and that ‘efforts to reinforce or reintroduce endangered species will be limited by the roads”.
Globally, species most likely to be killed on the roads included Tasmanian devils (native to Australia), Virginia opossums, San Clemente Island foxes (native to California), wild dogs (native to sub-Saharan Africa) and fox squirrels (native to North America).
The team also found that in some animal populations, up to 80% of all known mortality was due to collisions with vehicles.
More than half (58%) of all fox squirrel deaths in populations have been attributed to vehicles, as well as nearly half (46%) of opossum deaths, according to the study.
For the Iberian lynx in Spain – classified as “endangered” by the International Union for Conservation of Nature (IUCN) – 59% and 80% of total deaths in two populations were due to collisions with vehicles.
Meanwhile, 38% of the “endangered” wild dog populations and 48% of the “near-threatened” San Clemente Island fox populations were killed on the roads.
Of 50 Tasmanian devils – classified as “endangered” – released into the wild following captive breeding programs, researchers found that 38% had been killed on the roads.
The team also said the growth rate of “vulnerable” giant anteater populations in Brazil had been halved due to collisions with vehicles and that if this continued, populations would likely die out in about 10 years.
Other species also likely to be killed on the roads included common genets, western quolls, common wallaroos, gray wolves, gray foxes, American black bears and cougars.
Dr Silviu Petrovan, study co-author and lead researcher at the University of Cambridge, said: “We all see road accidents while driving but, as this study shows, this mortality can have very different for different species.”
Ms Moore added: “The effect of roads on wildlife populations is one of the most pressing contemporary conservation issues and, with the increase in road networks globally, we need to address this as soon as possible. urgently.
“Quantifying the impact of road mortality in this way is important in order to help influence road management and planning decisions, as well as future mitigation work.”
