ARLINGTON, VA — November is the peak month for vehicle-deer collisions, and a new analysis of insurance claims and federal crash data indicate the problem is growing.

The Highway Loss Data Institute (HLDI), an affiliate of the Insurance Institute for Highway Safety (IIHS), recently examined insurance claims for animal strikes under comprehensive coverage month by month from January 2005 through April 2008. The main finding is that insurance claims for animal collisions are nearly three times higher during November than the typical month earlier in the year.

For example, for every 1,000 insured vehicles, 14 claims were filed in November 2007 compared with an average of five claims per 1,000 during January-September. Insurance claims usually don't specify the animal involved, but other data show that deer are the main ones.

"Urban sprawl means suburbia and deer habitat intersect in many parts of the country," said Kim Hazelbaker, HLDI senior vice president. "If you're driving in areas where deer are prevalent, the caution flag is out, especially in November."

State Farm, the nation's largest auto insurer, estimated that there were more than 1.2 million claims for damage in crashes with animals during the last half of 2007 and the first half of 2008. The company said animal strike claims have increased 14.9 percent over the past five years.

Most vehicle-animal collisions aren't severe enough to injure people, but data from the federal government show that crash deaths are increasing. In 1993, 101 people died in crashes involving animals. By 2000, the number was 150, and in 2007 it was 223.

The states with the largest number of total deaths are Texas with 227 deaths during 1993-2007, Wisconsin with 123, and Pennsylvania with 112.

Analyzing monthly data on fatal crashes of passenger vehicles and animals during the past three years, IIHS researchers found patterns similar to those reported by HLDI. Depending on the year, the crash deaths occurred most frequently in October or November.

"The months with the most crash deaths coincide with fall breeding season," pointed out Anne McCartt, IIHS's senior vice president for research. "Crashes in which people are killed are most likely to occur in rural areas and on roads with speed limits of 55 mph or higher. They're also more likely to occur in darkness, at dusk, or at dawn."

When motorcycles are included, there's another peak in crashes in the summer when motorcycling is more common. Riders typically make up about half of the deaths in vehicle-animal crashes each year, even though registrations of cars, SUVs, and pickup trucks outnumber motorcycles on the road 40 to one.

Safety belt use is a major factor. IIHS research from 2005 examined 147 police reports on vehicle-animal collisions in which there was a human fatality in nine states during 2000-02. Deer were struck in three out of four of these crashes, but collisions with other animals such as cattle, horses, dogs and a bear also led to deaths.

Most of the crash deaths occurred after a motor vehicle had struck an animal and then run off the road or a motorcyclist had fallen off a bike. Many of these deaths wouldn't have occurred with appropriate protection. The study found that 60 percent of the people killed riding in vehicles weren't using safety belts, and 65 percent of those killed riding on motorcycles weren't wearing helmets.

"A majority of the people killed in these crashes weren't killed by contact with the animal," McCartt said. "As with other kinds of crashes, safety belts and motorcycle helmets could have prevented many of the deaths."