California spends more than $18 million a year to clean up animal carcasses that pose a threat to cars, according to Caltrans, the state transportation agency. The amount has increased fivefold since 2002.

Roadkill is costly to clear because California generally takes a more rigorous approach than most states. Here, Caltrans aims to rid roadways of carcasses within two hours after being alerted to them.

Removing roadkill is a significant challenge in such a sprawling state with 160,000 miles of roads and highways, and one of the country’s fastest-growing populations of deer, wild pigs and other wildlife.

A 2013 report by the California Roadkill Observation System estimated that state vehicles hit more than 2 million animals every year. Most of those carcasses (81%) are deer, followed by raccoons (18%) and birds (less than 1%).