By Katie Lannan
LOWELL -- The motion-detecting lights in Mary Ellen Ramsden's North Billerica yard go off about five or six times a night, triggered by rabbits hopping across the yard.
Lowellian George Dailey is used to protecting his parsley plants from hungry bunnies, but was surprised to see one of his rosebushes nibbled down to the ground, sticks and all.
Leaving for work one morning, Rich MacDonald found a baby rabbit eyeing him from right in front of his truck, a greeting that's becoming a common occurrence outside his Tewksbury home.
"I've got way too many for my little area," said MacDonald. "I'm seeing about 18, at least three pairs of adults and all the little ones they've got with them."
Ramsden, Dailey and MacDonald are among area residents who say they've been seeing unusual numbers of rabbits recently. According to Marion Larson, information and education chief at the state Division of Fisheries and Wildlife, it's just the annual bunny baby boom.
"At this time of year, it's certainly not unusual to see more rabbits than you did in the spring or in the winter," Larson said. "You know the term breeding like rabbits? It's true."
To Dailey, the extra bunnies bouncing around -- and taking bites out of his garden -- seem to suggest there's just too many of the critters this year.
"It's like they're overpopulated," he said. "It's definitely been on our radar this year."
That's not the case, Larson said. MassWildlife gets calls around this time annually, from residents discovering rabbit nests and wondering if they might be overrun.
The annual population surge actually belies the fact that one of the two species of cottontails in Massachusetts has seen its numbers dwindle so much that federal officials are considering designating it as endangered.
Throughout the Merrimack Valley, it's probably the more common Eastern cottontail burrowing through backyards. But Larson said her agency wants to find out if any of the critters in this part of the state could be the much rarer New England cottontail.
"There is a lot of effort by the different states to figure out where they are and ways to improve habitats for them," Larson said. "We don't have numbers, but most of them are in the southeastern part of the state, with some in the western part of the state. They could be in some other little pockets."
Attempts to restore the dense, shrubby brush favored by New England cottontails are under way across New England and New York. As part of this broader initiative, MassWildlife is looking to pinpoint exactly where in Massachusetts these particular rabbits already live.
The state is asking hunters, animal-control officers, highway workers and members of the public to submit to MassWildlife any cottontail skulls or carcasses they encounter as roadkill or hunting prey. This survey, launched in 2010, allows experts to determine which of the two near-identical species is in which location.
The native New England cottontails have slightly shorter ears and smaller bodies than their Eastern counterparts, which were introduced to the region by the thousands starting in the 1880s.
"You can't really tell them apart unless you're doing DNA sampling or looking at the suture marks on their skulls," Larson said.
Another difference between the species is their habitat. The New England cottontails require "really thick shrubbery, or a very thick tangle of saplings," Larson said.
While Eastern cottontails also like that type of environment, they're more willing to spend time in open space.
"The cottontails that most people are seeing on their lawns are most likely Eastern cottontails," Larson said. "They seem to be more flexible in the kinds of places that they live and will venture out."
Locally, the rabbits that are around seem to have no problem venturing out, according to MacDonald, who calls them "brazen," and other residents.
"You move from one end of the house to another, and there's one in the backyard and one in the front yard," Ramsden said. "It seems like they're moving around quite a bit from yard to yard back here. They're always hopping through a backyard or going under a fence."
Follow Katie Lannan on Twitter @katielannan.