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Bumper Crop of Acorns Boosts Squirrel Population

  • Secretive and small, grey squirrels are always the hardest to find for the annual Tonganoxie Squirrel Scramble. (Michael Pearce/Wichita Eagle/TNS)

  • Baby squirrels that were under the care of Catherine Greenleaf, of Lyme, before she released them back into the wild. (Courtesy of Catherine Greenleaf)

  • Baby squirrels that were under the care of Catherine Greenleaf, of Lyme, before she released them back into the wild. (Courtesy of Catherine Greenleaf)



Valley News Calendar Editor
Saturday, September 01, 2018

West Lebanon — It’s hard not to notice the increase in the number of squirrels in the Upper Valley this summer.

It seems like they’re everywhere, from trees to gardens to appearing as roadkill on the region’s roadways, where perhaps they draw the most attention.

But there’s an ecological explanation behind the eastern gray squirrel population boom.

“It was what we would call a bumper crop year for acorns,” said Haley Andreozzi, wildlife outreach program coordinator at the University of New Hampshire Cooperative Extension. “Most people are hypothesizing that that’s what has led to an increase in the squirrel population this year.”

Acorns are part of a crop group called masts, which refers to fruits and nuts produced by trees and shrubs. Horse chestnuts, hickory nuts and others that rodents including squirrels like to eat were in abundance in 2017, said Patrick Tate, wildlife biologist for the New Hampshire Department of Fish and Game.

“Those animals were able to overwinter very well,” Tate said.

They were able to squirrel away more fuel for last year’s winter.

“We think we’re seeing this increase in squirrel populations this year because they’ll increase reproduction if there’s an increase in food source,” Andreozzi said.

On a recent 6-mile run, she spotted about 10 squashed squirrels.

Squirrels are far from the only mammal that depends on the mast crop. There’s also been an increase in mice and chipmunks, though the public doesn’t notice them as much.

“They won’t travel as great distances as squirrels will,” Tate said.

Red squirrels and flying squirrels, which also make the Twin States home, are similarly effected. Gray squirrels are just the most prevalent.

“It’s a cycle playing out that’s highly visible,” Tate said. “If it wasn’t for motor vehicles, most wouldn’t notice.”

Red squirrels nest in coniferous trees and gray squirrels in mixed hardwood stands. Flying squirrels — with a different breed in the southern and northern parts of the state — aren’t seen much.

“They’re (gray squirrels) are slightly more adaptable to a wider ranger of habitats,” Andreozzi said. “They just tend to do better around human-dominated landscapes.”

An acorn bumper crop happens two years out of every decade. The overproduction is seen as a strategy for survival on the part of oak trees.

“The strategy for oaks ... means that in the years they’re producing more acorns is they have a greater chance in surviving to seedling then tree,” Andreozzi said.

She expects that with the mast crop returning to average this year, the animal population will too.

Squirrels breed twice a year, in late winter and mid summer, Tate said. The abundance of food meant more were surviving.

But the number of squirrels turning into roadkill is indicative that this year’s mast supply isn’t as strong.

“This time of year ... squirrels will normally start cutting acorns out of treetops. Where they’re not finding acorns, they’re moving around looking for food,” Tate said. “When they start moving like that, they’ll cross roads more frequently.”

When squirrels become nutritionally stressed, they’re not as alert. Their immune system also can become compromised, making them susceptible to disease and their reaction times slow.

“They don’t respond as quickly to moving vehicles,” Tate said.

Squirrels also begin looking elsewhere for food, leading them to gardens and orchards to eat unripe apples, peaches and even raspberries.

“They are known to do that, but normally the feeding damage isn’t quite as heavy as it is this year,” said Emma Erler, education center program coordinator at the UNH Extension.

This year, Erler has seen an increase in the volume of calls from frustrated gardeners and fruit growers who are struggling to keep squirrels away from their crops.

“They’re hard to control,” Erler said. “Once they find something they really like to eat, it’s hard to keep them away.”

Erler has recommended people use cloth to surround their plants to try to keep them out. Trapping is also an option.

“Large rat traps that are baited with peanut butter or fruit can be pretty effective,” she said. People also can try to use live traps and then relocate problem squirrels elsewhere. “You have to take them a long distance away because they’re going to be drawn to go back to their original territory.”

In both states, homeowners can legally trap and shoot squirrels on their own properties without a permit.

Gardens are far from the only place where squirrels are getting into trouble. JP Pest Services Wildlife Manager Scott Dillon, who has worked in pest control for about two decades, said more squirrels are finding their way into homes.

“It’s just an insane amount of squirrels this year,” he said. “I can’t not notice it and I’ve never noticed it like this.”

Dillon started noticing the increase last winter when the pest service, which has numerous locations throughout the Upper Valley, started getting more calls about squirrels of all varieties finding their way into homes.

“Generally bats keep us busy throughout the summer and squirrels tend to slow down,” Dillon said from the roof of a home where he was addressing a flying squirrel problem. “We have had a steady amount of squirrel activity through the summer.”

Squirrels usually enter structures through cracks in a roof or using their teeth to chew on trim to gain entry. Bird feeders also can attract them, as well as overlong tree branches.

“It just makes it easier for them to get to the roof,” Dillon said. “Once they get to the roof it makes it easier for them to find entry points.”

Once inside, they can do a significant amount of damage.

“Wire is the biggest concern,” Dillon said. They also can tear up insulation to make nests for a place to raise their young.

When out on the job, Dillon inspects roofs, looking for evidence of chewing and grease marks where squirrels go in and out. He places one-way doors so that they can get out for their nightly feedings but not come back in. He also needs to make sure the timing is right: If a squirrel is raising its young, homeowners may need to wait until the babies are old enough to exit themselves so that they don’t become separated from their parent squirrels.

“Timing is everything when it comes to excluding wildlife,” Dillon said. “If we can have everything happen naturally, it’s better for everyone, the homeowners and the animals.”

The longer squirrels stay in a home, the harder they are to evict and may become aggressive.

“When you do a one-way door and kick them out, it’s the same thing as when we lock ourselves out the front door ... We’re going to check every door to get back in,” Dillon said. “It’s home to them as well. They’re going to want to get back into their house.”

Natural Predators

There is no single animal that depends on squirrels, though they are eaten by other mammals including foxes, coyotes, bobcats and weasels. Birds, including owls and raptors, also eat them.

“It will likely help out our scavenger species,” Andreozzi said. That includes crows, ravens and turkey vultures. “They’re pretty happy with the amount of roadkill, I’d imagine.”

Both Vermont and New Hampshire have a hunting season for squirrels that began on Saturday. In Vermont, it lasts until Dec. 31, and in New Hampshire, Jan. 31.

“It’s not like deer hunting or turkey hunting,” Tate said. “It’s a low number of people who do it.”

Wildlife Enforcement

Fish and game officers rarely get involved with squirrel roadkill cases.

“They’re just big enough to notice and there’s a lot of them,” said Maj. George Scribner, deputy chief of Vermont’s Fish and Wildlife Department law enforcement division. “It’s a very common animal to get hit.”

Wildlife officers typically only respond to roadkill accidents that involve deer, bear and moose.

They have observed that there are more squirrels this year.

“You see squirrels everywhere just trying to eek out a living,” Scribner said. “The more they’re moving, the more they’re going to be susceptible to getting hit.”

If you accidentally hit and kill a squirrel with your vehicle, Scribner recommends leaving it.

“You don’t want to get out of your vehicle,” he said. “It’s not worth the risk of getting hit by a car if you hit a squirrel and want to get it out of the road. It becomes a public safety thing.”

Squirrels don’t really pose a danger to humans in terms of spreading a disease, although state Fish and Game officials recommend hunters use rubber gloves while processing them.

“What I would be more worried about is getting a tick bite off a squirrel,” Scribner said. “If they look or smell sick, we recommend that you don’t eat them.”

The best course of action is to let nature take its course and let the scavengers eat them off the road.

“I hate hitting any kind of animal, but it happens,” Scribner said. Recently, he hit a red squirrel after trying to miss it. “I was bummed out.”

Scribner said that safety should be key. It’s not wise to slam on the breaks if there is a car close behind.

“I try to avoid everything, but I would rather hit a squirrel or a deer than hit a person or another car,” he said.

Saving Squirrels

Wildlife rehabilitator Catherine Greenleaf, of Lyme, often takes in orphaned baby squirrels to nurse back to nature. Recently, someone brought her a baby squirrel that was found clinging to its mother’s body after she had been hit by a car.

“What caught my attention this year was the increase in the red squirrel population,” said Greenleaf, who runs St. Francis Wild Bird Center. About 10 percent of the animals she assists are squirrels. She’s also noticed an increase in squirrel roadkill the last few weeks. “This is the time of year where the juveniles are out scouting for territories. It has little to do with mating. The first-year youngsters are trying to find an area that they can call their home.”

The lifespan of a gray squirrel is rather short at only 2-5 years and that partly has to do with vehicles hitting them, Greenleaf said.

“It evens out and you know what evens them out? The cars running them over,” she said. “That’s what we call the great equalizer. It’s sad. It’s really sad that so many are getting run over.”

It can be hard for people to intervene, depending on the road.

“Sometimes it just isn’t safe to stop unfortunately,” Greenleaf said. Sometimes, squirrels will run halfway across the road, pause, and then run back. “That’s sometimes what polishes them off. That indecision in the middle of the road.”

Greenleaf said she took care of about a dozen baby squirrels this year, which is average for her.

She raises the orphans as a group, starting them in indoor cages before moving them outside. It takes about 14-16 weeks.

“They have to learn to climb and jump,” she said. “I always release them in a group.”

Good Samaritans also have brought her injured squirrels that they’ve found. She’s nursed several gray squirrels back to health who were suffering from head injuries.

“They did just fine,” she said. “You just keep them comfortable, keep them warm, give them lots of food.”

If someone finds an injured squirrel, Greenleaf recommends putting on gloves and placing it in a cardboard box with a towel on the bottom.

“The sooner you can get him to me, the better,” Greenleaf said. She can wrap a broken leg or let them recover in a safe environment from a head injury. “They’re very resilient animals and they bounce back very quickly, if they get help right away.”

Humans, in their desire to help baby squirrels, often can harm them. One common mistake is giving them milk from cows. “It’s well-intentioned but it can kill the squirrel.”

The first thing to do is to get them warm. Babies under 5 weeks old have not developed fur.

“When they’re tiny like that they can’t maintain their body temperature,” Greenleaf said.

While the high volume of acorns contributed to the population growth, humans have contributed to the death of squirrels.

“The more habitat destruction there is, the more roads that are put in and the more cars that are on the road, the more wildlife deaths we’re going to see,” Greenleaf said. “The Upper Valley needs to strike a balance between wildlife. They were here first.”

Editor’s note: If you find an injured or baby squirrel, contact Greenleaf at 603-795-4850. Liz Sauchelli can be reached at esauchelli@vnews.com or 603-727-3221.