SANTA CRUZ – The brightness of Sunday’s supermoon has a dark side: an increased risk of wildlife-vehicle collisions.

Nocturnal animals alter their activity levels depending on the phase of the moon. Researchers found a correlation between the frequency of wildlife-vehicle collisions and lunar phase — significantly more of these accidents occur during a full moon. And this next full moon will appear brighter and larger than normal because the moon will be closer to Earth in its orbit.

These wildlife accidents have an economic impact by causing a significant amount of injuries and property damage, explained Tom Langen, a biologist at Clarkson University in New York and co-author of the paper published online last month in the journal Biodiversity and Conservation. Insurance companies, as well as transportation departments, want to know if there are any predictable patterns, he said.

“People have sometimes suspected that [moonlight] might have an some affect on behavior and risk of accidents but it really hasn’t been looked at before,” said Langen. “Partially because it’s tricky to look at.”

Langen and his co-authors examined traffic accident reports from Spain and the U.S. for data related to four large hoofed mammal species. For the U.S., they focused on the white-tailed deer. They looked through more than 77,000 reports of wildlife-vehicle collisions in New York state from 2005 to 2007. Accident reports don’t report the weather conditions, phase of the moon or brightness of the moon at the hour of the accident, so the researchers had to supply that information from other sources.

Santa Cruz is home to black-tailed deer, not white-tailed deer, but Langen said he believes both species have similar activity patterns.

Jen Walker, the program manager at the Santa Cruz County Animal Shelter, said she believes it would be difficult to track all the necessary data to determine if there’s a similar pattern to wildlife collisions in Santa Cruz County. The data are split among different jurisdictions. Animal control programs may not hear about an accident if the highway patrol handles it on the road. Some collisions may not be reported.

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From the data Walker has, she has so far only noticed a spike in incidents during mating season in autumn.

Information from studying road ecology can guide the design of technologies that help prevent drivers from encountering animals. Langen said one tool that works well for deer are underpasses or tunnels.

Caltrans Public Information Officer Susana Cruz pointed to the use of underpasses in heavily trafficked areas by animals near Highway 17. A wildlife tunnel planned for Laurel Curve has an expected construction date of 2020.

One of the next steps could be to examine the activity levels of emergency responders and hospitals that deal with the aftermath of these accidents, Langen said.

The California Highway Patrol in Santa Cruz frequently sees collisions with deer along Highway 1 and Highway 17, but they aren’t as common as vehicle-vehicle collisions. “We wouldn’t deploy more people during a full moon than any other shift,” said Officer Trista Drake.

Still, Langen said that drivers having an heightened awareness during full moons may be helpful. But he cautions that these findings don’t mean a new moon is safe.