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"Walter P.Taylor and Arizona's Porcupines,"
by David E. Brown and Randall D. Babb

This article was published in the May-June 2008 issue of Arizona Wildlife Views magazine. Support Arizona's award-winning wildlife magazine — order online.


“A porcupine was killed south of Prescott a few days ago by Lute Wildon and presented to Dr. Miller of that place who will endeavor to preserve it. This is the first animal of that species ever seen in that section.” –“Tucson Daily Citizen,” Aug. 13, 1897

The question was simple enough: “When was the last time you saw a wild porcupine in Arizona?” To those of us asked, the answer came with a struggle as we pondered just how long ago our most recent sightings were, if indeed we had ever see one at all.

In truth, most Arizonans cannot recall ever seeing a porcupine in this state. It therefore comes as a surprise to learn that porcupines, historically and currently rare in Arizona, were so numerous in the 1920s and 1930s that the species was deemed a threat to the state’s forests. So great was this concern, that the porcupine was one of the first animals to be studied by a professional biologist.

Walter P. Taylor’s “Ecology and life history of the porcupine (Erethizon epixanthum) as related to the forests of Arizona and the Southwestern United States,” published as University of Arizona Biological Science Bulletin No. 3 in 1935, remains an interesting read. Stimulated by complaints from forest rangers that porcupines were damaging ponderosa pine trees, this 177-page booklet summarized what was then known of the porcupine’s life history and ecological role in Arizona’s forests while presenting suggestions on how to deal with this animal.

Taylor was ideally suited to be the study’s chief investigator. Born in 1882, he was a contemporary of Aldo Leopold and a pioneering wildlife biologist interested in ecological processes. After earning a doctorate at the University of California, Berkeley (where he also served as its museum’s curator of mammals), Taylor joined the U.S. Biological Survey in 1916. There he began a 35-year career in what would become the U.S. Fish and Wildlife Service.

Although a federal biologist, Taylor also retained ties to academia, taking the post of professor of economic zoology at the University of Arizona in 1922. At that time, there was no Arizona Game and Fish Commission. The Game and Fish Department had no biologists, being principally responsible for enforcing the state game code.

Interested primarily in mammals, Taylor spent most of his Arizona career (1922–1935) working on ground squirrels and jackrabbits — animals then considered economic liabilities. It was while studying these species, however, that he learned the basic principles of a science that came to be known as wildlife management, a discipline that led him to expand his role from rodent control biologist to professor of biology and wildlife conservationist. He helped found the Arizona Game Protective Association in 1923 and served on the editorial board of its magazine, Arizona Wildlife and Sportsman. In 1929, he helped author a new “game code,” the legislative initiative that established the Arizona Game and Fish Commission and Department that exist today. Taylor went on to earn the prestigious Aldo Leopold Award (1943), and to author the highly successful book, “Deer of North America” (1956). Moreover, his monograph on the porcupine remains the only study of this unusual animal in the Southwest.

The Study of Porcupines

Taylor began his study by sending out questionnaires to all offices of the Forest Service and U.S. Biological Survey in Arizona and New Mexico, requesting their porcupine observations. Respondents reported porcupines to be numerous and widely distributed, with sightings as far south as the Tucson area, in Sulphur Springs Valley and at the head of Aravaipa Canyon. Most reports were from the state’s ponderosa pine forests, however. The animals were especially abundant in Arizona on the Coconino and Tusayan (now South Kaibab) national forests.

Taylor followed up this preliminary survey with three years of field study in the vicinity of Fort Valley near Flagstaff beginning June 1924. Here he found that porcupines favored trees in cutover forests, and tended to favor ridges, gulches, rock piles, caves, crevices and meadows — the latter being especially important as the animals fed on herbaceous forbs throughout the summer. At other times the porcupines fed on inner bark, mistletoe, pine needles and fungi.

Reading Taylor’s 1935 monograph provides a window into a different time. Although much of the study was concerned with “porcupine work” and the amount of damage inflicted on the forest, we also learn a number of facts about the animal. We learn, for example, that porcupines can strip and consume 40 square inches of bark a day during the winter months, and that the density of porcupines was greatest in grazed forests, with little damage being done to virgin stands.

The trees most vulnerable to porcupine work were sapling and pole-sized ponderosa pines. Some trees were hit repeatedly. The principal damage was caused by porcupines girdling the trunks of smaller trees, causing them to develop a spike-top or stag-head appearance. When eating the “phloem” or inner bark of pine twigs, porcupines also cut off the terminal portion of the branch. (This is similar to the feeding behavior of a tassel-eared squirrel.)

The porcupine’s life history was studied as thoroughly as possible given the techniques then available. Taylor described the composition and character of the quills in great detail, along with the animal’s pungent odor, predilection for salt and breeding behavior. Mating occurred from late July to January, with most activity between Sept. 7 and Oct. 16. The “kit” — normally just one — was born in April or May and weaned by the end of July. Adult weights varied from 15 to 43 pounds, with the males typically heavier than the females. Porcupines were thought to be migratory, animals on San Francisco Mountain moving to lower elevations in winter when they might spend an entire month in a single tree. Most movement occurred at night.

However, accurate natural history information on some topics proved elusive, as live porcupines were nearly impossible to sex in the field. Moreover, certain reports from predator control agents, while dutifully recorded, come across as bizarre. M. E. Musgrave stated that porcupines mated in the missionary position, a phenomenon not seen by Taylor and his assistants. Another agent, E. M. Mercer, thought porcupines ate young prairie dogs, probably because porcupines often were reported seen in prairie-dog towns. The species also was said to be edible table fare and to make an acceptable pet, although these “benefits” were deemed to be minor. Although “porkies” were observed to drink “like horses,” the animal’s water requirements were never actually determined.

Conclusion: Forests in Danger

The main issue, however, was the sheer number of porcupines and the perceived damage being done to the forests. Although the study objective was to find a management solution rather than justify what was becoming an extermination campaign, the study concluded that no less than 500,000 acres of the Southwest’s forests were in danger from porcupines.

A serious effort was made to poison porcupines in the Flagstaff area beginning in 1922, and by 1930 a control program was encouraging predator-control agents, foresters, Civilian Conservation Corps crews and the general public to destroy porcupines at every opportunity. Hunters were urged to sharpen their sights by shooting porcupines, and participants at outdoor events earned prizes for killing the most porcupines.

This persecution of porcupines continued through the 1950s and 1960s until 1972, when a wildlife manager in Flagstaff named Wayne Anderson recommended that the season be closed on what was no longer a problem animal. Almost no one objected, and the Arizona Game and Fish Commission agreed: Conditions had changed. The porcupine was no longer a noxious animal and has remained a protected species in Arizona ever since.

Where Have the Porcupines Gone?

That porcupines were much more numerous in central Arizona forests during the 1920s and 1930s than today cannot be denied. Two of Taylor’s cooperators found 22 porcupines in 160 acres of forest near Fort Valley in 1924, and several individual trees on the Kendrick Park Road near Flagstaff yielded five to eight porcupines every fall for three years running. In one account, a professional hunter took 27 porcupines in one day; another predator control agent collected 40 porcupines while making his round of bait stations. Another was said to have counted 82 dead porcupines after poisoning selected trees with salted strychnine in 1926. Such tallies would be impossible today, and one is compelled to ask what caused this temporary increase in porcupine numbers.

Though a definitive answer to why porcupines were so numerous was beyond the scope of Taylor’s study, he nonetheless realized that the abundance of porcupines in west-central Arizona during the 1920s reflected abnormal conditions. Of the possible reasons then suggested for the excessive number of porcupines, Taylor considered that era’s reduction in the number of mountain lions (the porcupine’s only natural predator) to possibly be the most significant. The 1920s and 1930s were a period of intensive lion control effort designed to benefit livestock and deer populations, and government reports touted the belief that mountain lion numbers had been much reduced.

Although mountain lions were recognized as porcupine control agents, Taylor did not recommend a let-up in lion control, as biologists then considered removing porcupines to be a better solution than allowing lion predation on deer and livestock to return to former levels.

There is certainly no overpopulation of porcupines in Arizona now. In answer to a recent query to Arizona’s federal land management agencies, Coconino and South Kaibab national forest personnel reported less than two dozen sightings of porcupines since 2000. Only 15 of these sightings were in ponderosa pine forest. On the North Rim during the same time period, fire crews and other federal workers reported seeing “hundreds” of porcupines. However, almost everyone agrees these animals are now decidedly scarce south of Grand Canyon National Park.

Was a reduced lion population to blame for Taylor’s “porcupine problem?” We think so, and also believe that lions may be responsible for the present scarcity of porcupines. When predator control activities lessened in the 1970s, lions began to increase in distribution. As a result, porcupines are once again the enigma that prompted early Arizona naturalists to consider this animal a rarity. When was the last time you saw one?

“Mrs. I. D. Putman was in town this week from Dudleyville. She brought in the pelt of a huge Hedgehog her dogs had recently killed. These animals are scarce in southern Arizona.” –“Arizona Daily Star,” June 7, 1891

This article was published in the May-June 2008 issue of Arizona Wildlife Views magazine. To subscribe or give a gift, order online.

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