Last year’s rodent “bumper crop” means predator boom this spring

An ermine caught in a cage trap.

An ermine caught in a cage trap.

If you live in the Northeast, you’re probably aware of what local biologists dubbed a “squirrel-nado” of Increased rodent presence last year. Based on current trends, I have some predictions as to what New England’s wild-woods may be in for this summer.

Last spring, the Northeast bore witness to a heightened rodent presence the likes of which seemed unprecedented in recent times. It wasn’t long into the year before motorists began to notice an unusually high number of road-killed squirrels on the region's roadways.

By August, local news media had picked up the trend. New Hampshire DOT officials reported more than 100 squirrels struck on the state’s Spaulding Turnpike in the city of Rochester alone. Officials told reporters the tree-dwelling rodents were killed in unusually high numbers on the Everett Turnpike, as well as Interstates I-93 and I-293 - which made national headlines.

In Maine, sentiments were echoed. One motorist reported counting upwards of 508 squirrel carcasses between Freeport and Bangor on the Maine Turnpike, said Scott Lindsay, a wildlife biologist with the Maine Department of Inland Fisheries and Wildlife. “It’s not unusual to have up years for squirrels,” Lindsay told reporters in a phone interview, “But I don’t think I’ve ever seen a population this high.”

According to wildlife experts, the cause of last year’s unprecedented squirrel “boom” throughout New England, particularly in New Hampshire, was fueled by an abundance of acorns the year before.

The bumper crop in natural foods drove up rodent reproduction and larger litters. As a result, a greater percentage of rodents survived the 2017 winter, and those that emerged in the 2018 spring did so in above average health to breed and feed.

As nature would have it, those larger litters were met with a food shortage last year - making for “too many” squirrels and “not enough” food. This resulted in increased competition, mass migration, and rodent pandemonium in the region’s roadways, neighborhoods and farm fields.

In addition to the mass-exodus of squirrels running rampant through residential neighborhoods and highways, farm crops such as corn and fruit trees such as apples and peaches were almost completely stripped by the time harvest season rolled around, according to local farmers.

And it didn’t stop with just squirrels - the food-driven “rodent explosion” increased issues for local homeowners battling an influx in mice, Norway rats, voles, shrews, and other mammalian pests. While pest control companies reaped the benefits of a thriving rodent population, local residents and business owners were left scratching their heads.

Rodents weren’t the only wildlife to feel the strain of a food-driven boom and bust - New England’s bear issues exploded last year after desperate black bears with cubs of their own searched near and far for sustenance. The NH Fish & Game Department was embattled with nuisance bear calls throughout the state last year as starving mother bears began abandoning young cubs with no way to feed their offspring. Those orphaned and desperate bears inevitably found their way into city streets. Nuisance bears that couldn’t be euthanized or relocated were crammed into the state’s only civilian-run bear sanctuary at the behest of an otherwise unaware public.

By January, the tidal wave of rodent apocalypse had crested - and subsided.

In the Northeast’s icy winter grip, the brunt of nature’s “surplus” of rodents had frozen, succumbed to disease, or starved to death. By February, the rodent complaint calls flooding my wildlife management consulting business inbox were replaced with a different mammalian nuisance.

The next wave.

Just as the acorn mast abundance of two years ago drove a rodent explosion last year, I’m confident the expansion in rodent presence will drive a “cyclical boom” in New England’s predatory species this year.

The “squirrel-nado” which allowed bobcats, weasels, foxes, and other mesopredators to gorge on an endless “prey-buffet” this winter has now ended; and it will likely result in a carnivore wave set to crest this birthing season. The question is whether or not that wave will be a ripple in the forested bucket or a proverbial tsunami for local residents.

For the wildlife control operator, the “boom and bust” of predator and prey is typically first felt on the other end of the phone line. As the rodents were meeting their natural carrying capacity demise this winter, the calls came rolling in about “alien-like” white slender creatures popping up in residential dwellings.

The ermine, a wintry-white fur coat phase of the short-tailed weasel is well known for their robust rodent diet - and with those rodent resources decreasing, critters like weasels are now driven into new terrain to seek out furry pests “holed-up” in the walls of homes, barns, and chicken coops. From my plow driver, to the mailman - everyone seemed to be running into weasels at abnormally higher rates lately. I even took a call involving a parakeet breeder losing a substantial swath of his caged flock to depredation in an otherwise unsuspecting townhouse basement.

While the presence of a weasel in an old New England fieldstone farmhouse isn’t out of the norm, their occupancy in newer-construction homes is typically rare - making this winter’s steady flow of calls unique.

Now, as spring’s other “furry babies” are being born into the world, residential social media pages across New England are already bustling with post after post showcasing healthy fox litters - which seem to appear thriving thus far in large numbers under suburban sheds and barns.

A red fox forages in an urban backyard.

The trail-cameras from spring turkey hunters are regularly filled with robust bobcats, bounding mink, and brutish fisher all foraging for that missing “prey-explosion” that sustained them through the majority of the winter.

For those less fortunate, if starvation doesn’t bring about natural population control, a prey-based food shortage will likely force increased travel, resulting in the exacerbation of diseases like rabies and distemper passed by traveling furbearers. Desperation for a much-needed meal may also drive more brazen behavior and human conflicts from otherwise docile mesopredators such as foxes and bobcats.

I will say I make these assertions while emphasizing that these are natural occurrences - taking place year after year; albeit on a much smaller scale than the extremes the last three years have produced.

These predictions are also met with the contingency that a healthy mast and seed production this year may sustain many if they can make it through the “spring crunch” of a temporary decrease in prey sources.

Wildlife management agencies in both New Hampshire and Massachusetts wasted no time with press releases warning of nuisance bear issues this upcoming year, in an attempt to get ahead of the expected complaints. Any surviving bears that went into hibernation hungry last fall will be waking up and emerging with a ravishing appetite for dumpsters, birdseed and other easy digs.

Bottom line, farmers, pet owners, WCO’s, and backyard chicken-keepers throughout New England take heed - this year’s predatory youngins will likely need more nourishment than normal with last year’s food sources now depleted. Unlike the rodent populations, I suspect mesocarnivores won’t take “nature’s way” of “boom and bust” cycles lying down.