Collisions between wild deer and vehicles not only hinder conservation efforts but pose a serious danger to drivers. In new research, published in the Wildlife Society Bulletin, Canadian scientists examined locations and time periods of high rates of deer vehicle collision to assess the effectiveness of warning signs to prevent fatalities.
Property damage resulting from deer-vehicle collisions is estimated to cost $200 million a year in Canada and over $1 billion in the US. 90% of collisions are fatal to the deer, while 65% cause injury to humans. However, the team found that 77% of US and Canadian transport agencies rarely, if ever, employ prevention strategies for new projects and when warning signs were put up they were often placed arbitrarily.
"When you consider the amount of collisions that take place it is treated almost as common knowledge that deer-crossing warning signs don't work", said Dr Rob Found from the University Of Calgary. "Indeed with all the technology available to us there is skepticism that a sign stuck in the ground is able to reduce collisions with deer and save society millions of dollars."
The team focused their study on the city of Edmonton in Alberta, which borders dense forestry. The team used collision statistics from 2002 to 2007 to highlight key locations where collision rates were highest and coupled this with seasonal information to maximize the economic and safety benefits to preventing a collision.
The team identified 28 hotspots within the city limits before placing warning signs in 14 of these locations. The results showed that drivers did alter their speed for up to 1.6km after passing a warning sign.
The teams results also showed that while there had been 139 cases of collisions the previous year, the rate was dropped to 78 citywide once the signs were in place. The authors suggest that because warning signage is a cheap and easy prevention tool signs have become overused, but when placed selectively to target collision hotspots, they can still be effective at reducing collisions.
"Prevention strategies are not only a matter of saving the lives of both humans and deer, but also finding ways for deer and humans to share the same habitat," concluded Found. "Our study showed that warning signs really do reduce deer-vehicle collisions, but we will require a follow up study to determine if drivers remain responsive to these signs in the long term."
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The abstract of this paper is available free online: doi.wiley.com/10.1002/wsb.12