Even though it might be the safest, it is merely the least of all evils. One estimate from a Federal Highway Administration (FHWA) report to Congress in 2008 said collisions with wildlife cost motorists and taxpayers more than $8 billion per year. Although people rarely die from hitting a big animal, it can do a lot of damage to a car—and sometimes it can land a driver in the hospital.
The flip side is that hitting an animal can be dangerous for a species' longevity. The same report identified 21 species considered threatened or endangered in the United States, for which road mortality is "one of the major threats to their survival."
Many other species are far more common—such as white-tailed deer—but the report noted that every deer hit by a car is one that does not bring revenue to state-run hunting programs. While the number of auto crashes has held steady, the number of animal-related collisions have risen. The FHWA report said there were about about 300,000 such collisions reported annually as of 2008, and researchers believe that number is still low—some local government agencies do not have the resources to collect statistics, and some drivers don't report collisions.
Some ecologists, such as the Wildlife Conservation Society's Amanda Hardy, observe that smaller species, including birds, squirrels, and even reptiles and amphibians, usually are not counted at all.
"There is a lot of question about the actual numbers," Hardy said. "Many of us who work in the field have been pushing for a national data reporting standard. That could go a long way to helping us understand what is going on."
Insurance companies, however, have much higher figures.
State Farm estimates that there were 1.22 million collisions between deer and vehicles alone in the United States between July 1, 2012, and June 30, 2013. That was a slight decline over the previous year, which is encouraging. The FHWA report from 2008 showed that animal-related collisions became a larger and larger proportion of all auto accidents beginning in the mid-1990s to 2004. State Farm values damage to vehicles alone at about $4 billion a year.
Some times of the year are worse than others. During spring and fall, when animals are mating or migrating, roadkill numbers spike—and that number briefly jumps even higher near the beginning and end of daylight saving time. Scientists think this might be because animals are having trouble adjusting to the change in human commute times.