When winter arrives on the University of Minnesota campus, so do a few people who scope out campus evergreens, looking for a free Christmas tree.

But University Facilities Management is prepared. Employees spray evergreen trees on campus with skunk scent to deter thieves — a method that, while not foolproof, has helped reduce the number of thefts each year.

Thieves have stolen multiple types of evergreens in the past, including pine, spruce and fir trees. The skunk scent has cut the number of trees stolen each year from 10 to one or two, landscape supervisor Doug Lauer said.

Once the skunk spray dries, the smell isn’t noticeable. But if someone cuts down the tree and puts it in water, the needles release a pungent scent that’s difficult to remove.

Spraying campus trees is a cheap way to deter theft, he said. Ten one-ounce vials of skunk scent cost less than $50, and it takes one employee about three days to spray every campus tree.

Grounds Superintendent Les Potts said that although the spray has been effective, it needs to be used consistently. Facilities Management has used the spray in all but a couple of years in the past decade, but officials now plan to use it annually.

If someone steals a tree one year and encounters the skunk scent, he said, they likely won’t take a tree again. But because the odor isn’t immediately noticeable, those unaware of the spray will still cut down a tree.

“In a sense, it could be a preventative measure down the road, but it’s not a hundred percent,” Potts said.

Tree thieves occasionally climb a tall tree and cut off just the top 5 or 6 feet, Potts said. This forces Facilities Management to choose between cutting down the whole tree and simply leaving it without a top.

Losing trees can be costly. Lauer estimated that a 25-foot tree can be worth $2,000 to $3,000, plus the cost of maintenance. The bigger the tree, the greater the loss if it’s stolen, he said.

Lauer said he hopes the increasing number of security cameras on campus will help deter potential tree thieves.

Potts said Facilities Management plans to keep using skunk scent in the future, but he’s open to other methods of preventing tree theft.

The University of Michigan has also experienced tree theft and has found that publicizing the issue has helped reduce the number of problems.

Tom O’Dell, a University of Michigan areas specialist, said grounds maintenance workers write letters to local newspapers and post signs asking people to not cut down campus trees.

These measures have been successful, he said. But perhaps what was most effective was a case in which fraternity members were found guilty of stealing campus trees.

“That case was made somewhat public within the student population, and that helped a lot,” O’Dell said.