Needlepointers 
Look up through the tracery of the late winter trees.  The Rio Grande bosque has a surprise for you.
Like a spray of fruiting mistletoe, a dusky, dark sphere with white highlights is clinging tight
 to a topmost branch
A stealthy skunk?  A maverick monkey?  A stout stoat?  No, it’s a prickly porcupine!

              Noisy yet quiet, heavily armed yet vulnerable, antisocial yet even-tempered and take-it-easy tolerant, this nocturnal highliver is a salt-and-pepper paradox, a sweet-tart mix of opposites.  A porcupine may bumble and lumber on land, yet both male and female are strong swimmers, swift and sure when paddling across the river to snack on island salt cedar shoots.  Saber-clawed, porcupines may climb 60 feet high to feed far out on cottonwood limbs, balancing 25 or more pounds on branches no thicker than the width of a finger.   In exchange for this high-wire habit, they are prone to top-down falls, suffering injury and, not infrequently, death.
                Though rodents like rats, mice, squirrels, and beavers, the porcupine is an oddball among kinfolk in the order Rodentia.  While most relatives live fast, die young, and leave a multitude of offspring behind, the porcupine is a Methuselah among rodents:  some animals will succeed in gnawing through 18 long years of life.  Females devote seven months of each year to the production of a single infant, one of the longest gestations in the animal world, and will nurse their porcupet for another four months after that.
                Like the dark and light of their quilly, bristly, furry coats, North American porcupines are marvels of contradictions and contrasts.  For the wildlife observer in the Rio Grande bosque, they offer an extra lure:  findability.  Unlike the skittery lizard who vanishes into leaf litter; unlike the rare bird that flies off before binoculars can focus, find, and identify it, porcupines stay put in their daytime resting trees.  Unconcerned about a babble of excited voices on the ground, a portly porcupine will gaze sleepily at the forest of binoculars raised in her direction.  Then she’ll nod off for another nap.

Footing It, High and Wide        Short limbs and a slow, flat-footed gait notwithstanding, North American porcupines have come a long, long way from their ancestral origins in South America when prickly predecessors crossed the Panamanian land bridge in the early Pliocene period three million years ago.  Traveling farther than fellow South American migrants the opossum and the armadillo, North America’s only porcupine species eventually reached Alaska and the tree line of the High Arctic.  Today, Erethison dorsatum is the northernmost of the world’s 21, mostly tropical, porcupine species.           The North American continent south to Mexico and east to the Appalachians has provided a forest commissary of hardwood and softwood trees for this arboreal rodent to sample.  Wielding naked, pebbly-textured, tree-grasping paws that are nerved with a keen sense of touch and armed with long claws that can grip into bark like the grappling leg hooks of a telephone lineman, a hungry porcupine scampers up, up, and away on a summer night, slapping the bristles of his versatile, stabilizing tail against a tree trunk to feed on all the tree has to offer:  buds, twigs, leaves, flowers, and fruits.  (Porcupines rarely drink in summer since vegetation provides all the water they need.)  Topmost resources exhausted, the climber descends, coordinating claw holds and tail grips, down to the ground to feast on juicy tree roots.  With a little luck, he might find some salt-rich animal bones nearby to chew for a chaser.

                For an animal that feeds on vegetation far out on shaky, brittle branches, what goes up must come down ─ at times, breakbone hard down.  Although well adapted for the high life, porcupines are not immune to impalement on their own quills following falls.  (One museum study of skeletons revealed that 30 % of the animals had suffered fractures, many of which had healed, indicating post-fall survival.)  Evolution has given porcupines a remarkable trait that has helped many rebound after a mishap:  antibiotics in their quills.

Those Agonizing, Mesmerizing, Fido-incising Quills
                With a body count of 30,000 quills sprouting everywhere except belly, muzzle, and ears, the porcupine is a living fortress and a spiked artillery attack unit.  Quills are tools of many uses ─ Swiss Army knives that support, protect, and defend their owner.  Conspicuously black with white tips, and containing a fluorescent material to warn off nighttime predators, quills are modified guard hairs.  Each is from one half to four inches long and has shingle-lapped barbs at the tip for easy entry.  Once inside, the barbs expand as muscles of the victim contract, pulling quills deeper and deeper into the flesh; body heat increases air pressure inside the quills, making them hard to extract.  Quills on the back of the porcupine’s club-like tail, its principal slap-propelled shaft stabber*, are very special:  they have a greasy coating that keeps them stiff and rainproof while providing lubrication to burrow deep into the victim.  Moreover, these particular quills contain fatty acids that inhibit the growth of six Gram-positive bacteria including those that cause tetanus and gas gangrene, infections that could finish off an unfortunate animal impaled on its own weaponry after a fall.  Though damaged and down on the ground, an immobile porcupine might still be protected from a once-burned-twice-shy predator, mindful of the quill’s pain potential; the wounded animal thereby would gain a measure of recovery time along with aid from the quill’s antibiotic component.  (Porcupines will also use their incisors and formidable four-fingered front paws to remove quills.)
                Finally, porcupine quills contain a spongy material that provides water-wing buoyancy for a plump animal clambering down a riverbank and dogpaddling through the waves to an island food source.

Predator Proof?
                Hungry carnivores lurk in the hills, hollows, and forests of the porcupine’s world.  In the northern U.S., the agile fisher has become a porcupine specialist, lunging in and out to attack the rodent’s bare face; in the West, it’s the mountain lion.  One Nevada study showed that of 98 radio-collared porcupines, 95 of them had been killed when flipped over and rendered supine by the big cat. In the Southwest, there are other predators ─  bobcats, foxes, coyotes, and great-horned owls that score a rare kill.  Although a lucky hit to a vital organ can kill a predator, some will tolerate the porcupine’s quill defense ─ and if infected, receive a dose of antibiotic at the same time. 
                Although quills are the most famous weapon that this generally peaceable vegetarian uses to deter enemies, a painful tailslap is actually the act of a fighter with its back to the wall, giving its final, and most pointed, warning.
                A naïve, hungry coyote is hunting at night.  He spots something moving down a tree.  Although alerted to the black and white coloration on the animal’s head and back, the coyote ignores the warning and creeps closer. Next, he encounters an unfamiliar stop-and-start rasping sound, an ominous clacking and chattering of teeth.  If the coyote persists, he’ll be overwhelmed by a goaty, powerful, can’t-stand-it smell that the porcupine releases from the rosette, a bare-skin area at the base of the tail.  What’s next for this predator?  Likely, a muzzle-load of quills.  He’s naïve no more.

And Baby Makes Three
                When it comes to reproduction, the female porcupine is a reticent rodent, unreceptive except for a once-a-year, eight-to-twelve hour period when she’s in estrus.  Does anticipation of close, quilly contact keep male and female apart, as many a wag has suggested?  (“How do porcupines make love?  Very carefully!”)  And what about discomfort for the female enduring the birth of a quilly baby?
                While the story of porcupine reproduction indeed has its points of interest, fear of pain and impalement is not one of them.  First job for these solitary animals:  find each other. 
                In early fall, before winter snows halt most porcupine movement, males begin to expand their home ranges, wandering far and wide with noses on alert.  Females entice and cooperate with high-pitched cries and urine-borne olfactory signals.  If she attracts more than one suitor, the contenders are likely to have at it, shrieking and screaming, gouging out fur and flesh with their hard, sharp, orange incisors, and flailing away with tail slaps until the ground is boot-deep in quills.  The largest and heaviest male usually wins the day.
                Then comes a weird, unexplained male behavior:  he hoses down the female with urine.  If she’s not interested, she shakes off the shower; if she likes his saucy attention, courtship continues.  The two rise up on their hind feet, whine, grunt, rub noses, and embrace with gentle cuffing and paws placed on each other’s shoulders.  Then it’s down to the ground and down to business.
                The female elevates her hind quarters and swings her dangerous tail out of the way.  After copulation, a vaginal plug forms, perhaps to bar the door for other hose-happy males.  After 210 days of gestation, a one-pound baby is born, covered in fur along with short, soft quills, and wrapped in its amnion sac.  Quills harden in a few hours; although the precocious porcupet can walk and climb trees within days of birth, it will nurse and then sample vegetation beside its mother for up to five months, a lengthy dependency that some attribute to the low nutritive value of the porcupine’s leafeater’s diet. 
 

sunny, blustery morning in January.  Students from the Bosque School mill along a forest trail behind their North Valley campus, nudging, chatting, and catching up on news, views, and rendezvous.  At the silent ring of an unseen bell, all eyes and ears turn to science teacher Dan Shaw.
                “OK, I need four kids to collect sticks straight as possible, four more to carry the animal back from the tree to here, and one to give the injection,” declared Shaw. 
                During the previous night, a male porcupine, high in a slender mulberry tree, had caught the scent of salted apples and peanut butter.  Yes!  Here was a welcome change from his dreary winter survival diet of tree cambium, the nutrient-poor inner bark he’d been chewing from the mulberry’s upper branches.  Descending carefully, the hungry animal found his treat ─ but it was inside a Havahart® catch-and-release trap that Shaw had set and baited the night before.  The porcupine’s fair deal:  a tasty meal in exchange for a quick weigh-in and a veterinary once-over by caring examiners.

Thorny Fieldwork            In 2008, Shaw and his students entered the sixth year of the school’s Bosque Porcupine Project, a long-term study seeking to provide basic data and natural history information about porcupines in the Middle Rio Grande Valley and document their effect on cottonwoods and other components of the forest ecosystem.  Upperclass students in Shaw’s Wildlife Biology and Conservation class have learned how to process the captured animals, while his sixth graders assist and monitor the work.           To complement twelve years of data derived from Bosque Ecosystem Monitoring Program studies, an inter-agency research effort that continues to use students and teachers to monitor production and consumption of organic matter and nutrients in the riparian forest (bosqueschool.org/bemp.htm), Shaw has focused his porcupine surveys on areas surrounding eleven of BEMP’s 25 sites.  His prime target:  two sites of five acres each within a 113-acre stretch between Montaño Bouldevard and the Oxbow, east of the school’s campus. Working intensively in fall and winter months, Shaw and his student crew, along with veterinarian Susan Dicks, (“We never handle porcupines unless a vet is present,” noted Shaw) have examined some 20 animals since 2003, with a capture rate of about 50% of traps set.  Following sedation, the porcupines are implanted with microchips for later identification.  Each animal receives a wear-away radio collar with a six-month battery and a six-digit frequency number that trackers can capture on one of the school’s three antennas.

Hefty Handiwork Photo: Dan Shaw

Quill Drill
                With all equipment on hand and all hands on deck, the morning’s field work began.  After a short walk through the bosque, the porcupine hunters reached the trap Shaw had set at the base of the mulberry tree:  a square frame of chicken wire four feet high with a two-foot band inside and a dark tarp over the top.  Arranging the straight sticks collected by his students, Shaw carefully funneled the porcupine out of the trap and into a cage for transport to the animal’s outdoor exam room:  the rear of a truck, waiting back on the trail.  Once there, veterinarian Dicks took charge.
                First weighing the animal to calibrate the correct drug dosage (l1.5 kg or about 23 pounds indicating .4 ml/kg ─ “a whopper dose,” commented Dr. Dicks, “more than dogs and wolves get”), she then discussed and demonstrated all phases of the injection process for the students:  how to draw the drug up without getting air in the syringe; how to find a patch of skin on the porcupine’s rump (“Remember, the tail and the mouth are your danger zones”); and how to avoid hitting a blood vessel which would sedate the animal too quickly.  “Go in at an angle,” she advised her volunteer injector, junior Addy Gordon, who had pulled on super-heavy gloves, “and steady the needle with your left hand.”
                Fifteen minutes later, the patient was dozing and stretched out on his belly, heart rate and pulse checked and declared normal.  A recaptured male wearing a radio collar, he was over three years old, down about two pounds from his previous weigh-in last year.  He also had a nasty smell ─ an infection revealed when his inch-wide collar was removed.  Quickly, the team switched from fieldwork science to Plan B:  veterinary care. 
                After clipping the area and swabbing it clean, Dr. Dicks applied a triple antibiotic ointment to the laceration. “Our priorities are always human safety, animal welfare, and scientific inquiry in that order,” noted Shaw, adding “today is only the second time in all these years that the radio collar has caused trouble.”
                Carried back to the forest and released at the base of his mulberry feeding tree, the now collarless porcupine received his second prick of the morning:  a shot to reverse the sedative.  Four minutes later, he was on his feet.  Urged on by a shoe nudge from Shaw, he slapped his armored tail sleepily back and forth, offering his indignant opinion of the day’s events and providing a clear crescendo to end them.

                Animal work completed, Shaw took a moment to talk about the porcupine project, with additional research data supplied by senior student Katie Elder.

Scanimals
                Of the twenty porcupines caught since 2003, reported the investigators, tooth eruptions indicated that most animals were over two years old.  Ten were males, eight were females, and two were unsexed; weights ranged from 2.5 kg to 9.5 kg with some of the females pregnant.  Lice infestations, which some scientists believe may be beneficial to the host by cleaning away excess fur-clotting grease and dead skin cells, ranged from heavy to none at all.
                Gauging tree preferences, a porcupine at rest is almost always a provincial, parked in a cottonwood, said Shaw.  When hungry, he becomes a cosmopolitan.  “We’ve found that porcupines in our bosque will feed on just about any woody stem they can grab,” he said.  “That includes mature cottonwoods, New Mexico olives, coyote willow and Gooding’s willow, along with exotic Russian olive, mulberry, Siberian elm, tree of heaven (ailanthus), and tamarisk or salt cedar.”  As for the porcupine’s effect on the native plant community, neither Shaw nor Elder see cause for alarm.  Although porcupines are considered bark-stripping, tree-killing pests in many parts of their North American range, “bosque porcupines don’t girdle our cottonwoods like they do Russian olives,” Shaw noted.  “The bark’s too tough.  Although he and Elder have seen invasive salt cedar and Russian olive trees nearly bark-naked, these chewed up invasive exotics will still regenerate from stumps, Shaw added.  During winter-to-spring river island surveys that Shaw and his students have conducted by canoe, they’ve noted many signs of porcupine excavation ─ salt cedar stems dug up by these river-swimming, salt-loving rodents.  “Porcupines make use of the islands along with beavers and rare tawny-bellied cotton rats,” Shaw said, apparently an amicable arrangement for all.
                Where in the bosque do porcupines hang out?
                “We find animals in all stretches of the bosque with extensive winter overlap of individual home ranges,” Shaw answered.  “The acreage behind our school, with its mature cottonwoods and full understory of deep brush piles, has one of the densest populations with about one animal every eight to ten acres compared to one every 16 to 25 acres in other parts of the bosque with less favorable habitat.”  Porcupines use dens, too, he continued ─ abandoned beaver dens, culverts, and deep brush piles, but they don’t overwinter in them.  “We regularly see porcupines out during really cold weather,” he remarked.  “In fact, during one six-week period in late December 2006 that included a snow and ice storm, one female with a radio collar was content to stay put in her cottonwood feeding tree.  Later, she moved north to Montaño,” he continued,  “then came back to the same tree.”
                What about predators in the bosque?
                With no mountain lions around, humans and their cars are the main cause of death here, noted Shaw.  Coyotes and bobcats will take some, but great-horned owls may be wary.  “I’ve seen porcupines high up in the same trees with the owls,” he said.

Reaping Rodent Rewards
                As for the mechanics of capture and handling, Shaw’s project is the first to test the efficacy of the sedative Domitor® and its reversal agent Antisedan® on porcupines with no adverse reactions noted.  In February, students Elder and Anna Pérez-Umphry won the best student poster award for their drug research display presented at the annual joint meeting of the New Mexico and Arizona chapters of the Wildlife Society and the American Fisheries Society.  Competitors for the award were university undergraduates and graduate students, noted Shaw.  “I’m very proud of Katie and Anna.”
                In 2008, The Bosque School’s porcupine project continues on a roll and is ripe for expansion.  Next step:  identifying relationships among animals.  “As soon as we have enough hair and quill samples, we plan to do DNA analysis on them via electrophoresis,” said Shaw.  “Probably next year.  We also want to look at where the animals move in summer.”  Publication of project results is also likely next year, added Elder.
                 “Porcupines are great ambassadors for kids,” Shaw remarked.  “They are adapting and doing well in an urban habitat, making a living and getting their needs met among us, right here,” he noted.  “Also, porcupines are idiosyncratic with their quills, their double-digit life spans, and their sloth-like behavior,” he continued.  Observable and interesting for student-scientists and Nature Center observers alike, “they build a connection to the wild.”

                Look up into the tracery of the late winter trees. 

Sources: 

Alaska Department of Fish & Game.  Porcupine.  http://www.adfg.state.ak.us/pubs/notebook/smgame; Katie Elder and Anna Pérez-Umphry. 2008.  Poster Exhibit:  North American porcupine (Erethizon dorsatum):  live capture technique and the effectiveness of using the sedative medetomidine hydrochloride (Domitor®) and the antagonist atipamezole hydrochloride (Antisedan®) to facilitate handling; New Mexico Department of Game and Fish.  Wildlife notes: porcupine Erithison dorsatum.  www/wildlife.state.nm.us/education/wildlife_notes/documents/porcupine.pdf; North American Porcupine (Erethizon dorsatum) research and bosque porcupine project – research plan.  http://www.bosqueschool.org/bemp.porcupine.htm; Ronald Nowak and John Paradiso.  Walker’s mammals of the world, 4^th ed. 1983.  Baltimore:  The Johns Hopkins Press; Uldis Roze. 1989.  The North American porcupine.  Washington, D.C.: Smithsonian Press; Uldis Roze. 2006.  “Smart weapons.” Natural History 115 (2) 48-53;  Katie Elder; Dan Shaw.