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In springtime, porcupines cause me headaches.

I knew I should have put the steel stovepipe sections around the trunk of the weeping willow. By the time I returned home, there were five full wheelbarrow loads of tender yellow-green willow switches all over the front lawn and adjacent dirt road.

The willow survived winter ice storms only to be savaged by a prickle of hungry porcupines just before its most beautiful time, when willow buds burst into bright yellow catkins followed by slender green leaves. My neighbor snapped a few photos for me: four fat porcupines silhouetted at sunset, munching happily.

Porcupines favor tender, nutritious willow bark on young green switches. It’s like cheesecake for them, as far as I can tell.

I encase the willow trunk with rusty-black stovepipe sections as a slippery steel barrier to keep porcupines from climbing: a low-tech, non-lethal ecological solution to my perennial Porkie problems.

I raked up the whiplike willow switches covering the front lawn, filling a wheelbarrow five times with incisor-chiseled branches. After the stovepipes went up, they haven’t climbed it since.

We live in porcupine Eden. The jumble of boulders beneath steep, south-facing ledges on Meetinghouse Hill above our farm provides a quill-pig condominium complex of winter dens. We don’t own dogs anymore — too many quill issues. Grassy, wet pastures green up early with clover and dandelions. Tender apple and pear trees provide dessert, with fallen fruits in autumn and bark in winter and spring.

Springtime weeping-willow bark is a particular delicacy for porcupines, I have learned. Porcupines also graze tender wildflowers, fern fiddleheads, clover and ornamental shrubs and vegetable gardens. Thin-barked trees and shrubs have tasty, photosynthetic tissue beneath the outer bark, particularly on younger twigs. Twigs and bark of apple, birch, beech, aspen (poplar), slippery elm, maples, hobblebush and willow are porcupine favorites.

Willow bark contains a particular chemical compound, salicin. Human digestive tracts convert salicin to salicylic acid, a natural pain reliever and anti-inflammatory. Native Americans chewed or made poultices from willow bark for pain relief. In the late 1800s, European chemists extracted salicylic acid from willow bark to reduce pain and fever. Later, salicylic acid was synthesized to acetyl-salicyclic acid, the compound that is the active ingredient in modern aspirin and often buffered to prevent stomach distress from excess acid.

Porcupines: Scourge of the springtime willow tree

Porcupines: Scourge of the springtime willow tree

Through most of the 20th century, the state paid hunters a bounty for each porcupine killed. Populations today are much lower, in part because of the reintroduction of fishers.

Porcupines do give me headaches. For much of the year, they’re benign neighbors. While strictly vegetarian and generally passive, they remain a nuisance because of the damage they cause to trees and wooden buildings. In addition to plant material, porcupines crave salt and are attracted to objects that have salty human sweat on them, such as ax handles or boat oars. I’ve read they will chew salty rubber tires.

They can decimate a vegetable garden overnight, eating tender squash and cucumber vines and fruits. They are hellish on tender ornamental landscaping and our favored fruit and shade trees.

Winter months are particularly difficult for porcupines. They do not hibernate. Instead they subsist on a high-fiber starvation diet of bitter bark and hemlock needles laced with tannic acid and conifer compounds called “terpenoids” produced to ward off browsing herbivores.

Unlike browsing deer or moose with multiple stomachs, porcupines digest winter food slowly, taking nearly 40 hours — twice as long as other tree-bark eaters — to process their food. Porcupines typically lose 15 to 30% of their body weight during winter. A tender green salad of May vegetation comprises a welcome Mother’s Day breakfast at the end of winter.

Adult porcupines weigh 13 to 20 pounds and can have nearly 40,000 quills covering their bodies (except their faces and bellies). A typical porcupine’s home range is about 50 acres. They will live in colonies and are social with a range of grunting and squealing sounds, particularly during their September breeding season. Females give birth to a single baby “porcupette” in April after a 7-month gestation.

Porcupines: Scourge of the springtime willow tree

Steel stovepipe sections are a non-lethal and low-tech solution to keep porcupines from climbing a favorite front-yard willow tree. This particular front yard is located near favorite porcupine habitat, which includes ledges for winter den sites.

Live (Porcupine) Free or Die?

In 1903, New Hampshire was overrun with porcupines. The state paid a bounty per porcupine from approximately 1903 until the law was repealed in 1979. New Hampshire was the last state to repeal its porcupine bounty, which peaked at 50 cents per porcupine nose.

I’ve met more than a few old-timers who relate how creative stitchery could transform a sole pad into a fake porcupine nose to reap more cash per kill. While a bounty seems almost unthinkable now, if you have rural New Hampshire farm roots, your grandfather would attest it’s true. The reintroduction of fishers to New England in the 1960s is credited with reducing the porcupine population and keeping the current population in check.

My front lawn weeping-willow quill pigs climbed as high as they could to access the most tender branches. They snipped off each, gnawing the cut end before dropping them to the ground and moving on to cut another. Our now-ragged weeping willow will survive but the pruning was not artful.

I guess all those quills must give them some kind of headaches, too. Why else their fixation each May with chewing on willow trees?

Naturalist Dave Anderson is senior director of education for The Society for the Protection of New Hampshire Forests. Contact him at danderson@forestsociety.org. Forest Journal runs every other week in the Sunday News.