The Antietam, Manassas and Monocacy battlefields were once the sight of bloody invasions during the American Civil War, but now a new kind of intruder has taken over: white-tailed deer.

The National Parks Service has tentatively approved a plan that will allow sharpshooters to kill more than 2,800 white-tailed deer at three Civil War battlefields in Maryland and Virginia over the next five years to curb damage to plants and trees, The Associated Press (AP) reported.

With public hunting prohibited in the parks, the deer per square mile ratio has soared above 130 at Antietam, 172 at Manassas and 235 at Monocacy, the park service said - normal is considered to be 15 to 20 deer per square mile.

However, some hunters are criticizing the $1.8 million plan because they believe they could easily control the local deer population, without the need to hire sharpshooters from the Agriculture Department's Wildlife Services.

"It's ridiculous for taxpayers to pay $1.8 million to have deer taken off a property," Deer & Deer Hunting magazine editor Daniel Schmidt told the AP.

The Parks Service has also considered using chemical contraceptives to keep deer herds in check.

If this program is implemented, about 58 percent of the deer would be killed at Manassas, which is about three times bigger than either Maryland battlefield.

Spokeswoman Jenny Anzelmo-Sarles also added that the number of deer to be killed would depend on how quickly the forest regenerates.

"We maintain that lethal control is neither a socially acceptable practice nor, in our opinion, in the long term, the most ecologically sound approach to resolving conflicts with deer," said Stephanie Boyles Griffin of the Humane Society of the United States.

The Parks Service is expected to make a formal decision on the plan after the period for public review ends on September 3.

White-tailed deer, according to National Geographic, are found from southern Canada to South America. Female deer, or does, give birth to one to three young at a time, typically in May or June. Deer feed on all types of vegetation, like leaves, twigs, fruits and nuts, grass and even corn.

And though their numbers were previously depleted due to unrestricted hunting in the United States, stricter game-management rules have helped their numbers recover to the point that now, clearly, they are a problem.