You may want to make room under the mattress for your hammer drill .

According to police, power tools and construction supplies have become popular among Evanston burglars, who have found the items easy to steal and sell.

Christian Construction Services lost about $2,000 in equipment Thursday night when a vacant single family home it was renovating was burglarized, said Cmdr. Michael Perry of Evanston Police Department. The offender broke into the house, located on the 2000 block of Pratt Court, by prying open a locked door.

EPD received 31 reports of burglaries to construction sites and construction trailers between Aug. 1 and Nov.8, said EPD crime analyst Mike Pearlman.

“The number seems high, but that is indicative of the fact that there are a lot of construction projects going on in the city right now,” he said.

One of the factors that makes power tools such a desirable target is their natural liquidity, Perry said. The burglars, some of whom may work in groups, sell the stolen goods to buyers on the street and at local flea markets.

“There is absolutely a black market” for stolen power tools, said Jay Haberkorn, owner of Bonus Electric Company in Lemont, Ill. He said his crew was once approached by a man selling used tools that had another electrical contractor’s label.

Perry said it is difficult to retrieve the stolen tools, especially if contractors do not write down the items’ serial numbers.

“It’s an impossible task. We can’t go to all the flea markets” to look for stolen tools, he said.

The Maxwell Street flea market in Chicago was a major outlet for stolen power tools before it was shut down several years ago. Haberkorn once received a tip that his company’s tools were being sold at the market, he said.

Neighborhoods around downtown Evanston and on Maple Street have been hit hardest in recent months.

Construction sites are frequently burglarized because they are difficult to secure, Perry said.

Burglars often cut the site’s fence and crawl in late at night and on weekends when crews leave their supplies in locked “gang boxes.”

About nine out of 10 construction site burglaries occur at night, Haberkorn said. His company has reported many burglaries since it opened in 1979, including one on the 1600 block of Emerson St. on Oct. 23.

The likelihood of a site being harmed depends on “the location and the security of the site,” Haberkorn said.

At the Emerson site, Bonus Electric stored tools in a locked “theft proof” gang box in a dead-bolted room with cinder block walls. But someone used a pry tool to enter the room and break the lock of the gang box.

Some building owners and general contractors beef up security by employing armed guards or placing guard dogs on the site after working hours, but some offenders still manage to break in, Haberkorn said.

At a site where Bonus Electric was working about three years ago, four Rottweilers were beaten to death with baseball bats on a night when the building was burglarized.

Haberkorn said the offenders are almost impossible to stop. “They will do anything to get into a building,” he said.

But Haberkorn’s company is dedicated to preventing crime on its site.

“We never leave a tool unattended” he said. “Even during the day.”