Already plagued by little food and shelter from winter storms, the state’s troubled deer herd has a new problem to contend with – Fido.

The Maine Warden Service is urging pet owners to keep their dogs leashed and supervised as more and more household pets are threatening, injuring and in some instances, even killing deer already weak from hunger and harsh winter conditions.

“Deer have been going into neighborhoods and eating ornamental shrubs,” said Deborah Turcotte, a spokeswoman for the state Department of Inland Fisheries and Wildlife. “The deer are searching for food and dogs get out and go after them.”

Already this year, wildlife experts are projecting a 30 percent drop in the deer population due to heavy snows making it hard for the animals to make their way to winter yards, which offer some food and trees that provide shelter. Turcotte said experts estimate that translates to 10 years before the deer herd will be back to its present population.

Officials are urging pet owners not to allow their animals to chase deer due to their already weakened condition.

“Deer throughout the state are starving and are seeking food near roadways and in neighborhoods,” said Greg Sanborn, acting colonel of the Maine Warden Service. “Because they are so hungry, in many instances they are too weak to run or put up a fight.”

Sanborn reminded residents that it is against the law to have a dog unsupervised off a leash. Dog owners face a minimum $500 fine for each violation.

Lee Kantar, lead deer biologist with the department, added that the reduction in population could also mean a reduction in deer permits issued next fall – possibly by as many as 15,000. In 2007, 66,000 hunting permits were issued statewide.

Kantar explained that deer in winter yards rely on fat reserves from the previous fall to survive a winter. Good deer yards help slow the downhill slide of fat reserve use by providing thermal protection and some limited food sources. This season’s deep snow pack has made it difficult for deer on two fronts. On one hand, it’s hard for the animals to get to the yards. On the other hand, many get stuck once they get there.

“Everybody needs to understand that this has been a really rough winter for deer,” Kantar said. “They don’t need any kind of added stress, and there are always issues with dogs running loose. You can really tax a deer pretty quick in these conditions.”