3 theories about the declining porcupine population in Oregon.

Have you seen any porcupines lately?

INTRODUCTION

The porcupine population in Oregon is declining, according to various naturalists’ anecdotal reports and studies. There are a few theories as to why the population has declined. However, we still have a lot to learn about Porcupines and the role they play in the ecology of the Cascades. More and more, scientists are beginning to turn their attention to these spiky little friends. Cascadia Wild volunteers have already begun setting salt soaked wooden blocks as lure at our trail camera sites to help us detect porcupines.  We will continue monitoring efforts through the summer in  Mount Hood National Forest to assist Oregon Department of Fish and Wildlife (ODFW) biologists. Without further adieux, here's what we know about porcupines and 3 theories that may help explain the stark decline in porcupine's population.

AN OVERVIEW OF PORCUPINES

Porcupines are rodents that are known for their iconic quills, of which they can have up to 30,000. Their quills help them against predation, more on this later. Porcupines live all over Oregon, at one point in time, there were massive concentrations in the East Cascades region. Except for a few less than optimal adaptations, they are extremely resilient animals. They are found on every continent except Antarctica, but prefer to live in mixed coniferous and hardwood forests and some rockier areas.4 This  habitat preference may be changing, however, according to studies that suggest “an apparent shift in the distribution of porcupines away from forested areas and toward grassland and desert scrub habitats.”1

In terms of range, porcupines can roam anywhere from 6 to 14 acres, although they have been known to walk across states to find a suitable home.

Porcupines are vegetarian, eating foods like twigs, roots, stems, berries, needles, bark, etc.4 ​As a result, they crave salt, because their primarily herbivorous diets naturally lead to a sodium deficiency. 

Hence why our volunteers are hiking into Mount Hood National Forest with salt soaked wood. The diet of a porcupine is ecologically significant because as they consume trees they are creating spaces for other animals to live. 

​We’re just beginning to understand the ecological significance of Porcupines, whether it’s creating habitats or keeping brush under control.2 

FUN FACT: Porcupines have good memories and especially recall being mistreated, so be nice!!

Porcupine scat, from Spice Bush Blog.

However, Porcupines have for a long time held a well established Cultural significance in Native American cultures across Turtle Island. In oral parables, Porcupines are characterized as humble creatures with a child-like innocence. They can represent much more powerful medicines too, though, like faith and trust. Additionally, Porcupine needles are often harvested and used to create beautiful and elaborate embroidered art, called Quillwork. Some of these pieces include sheaths for knives to regalia for ceremonies and more. The needles are also a symbol of protection.

WHEN WAS THE LAST TIME YOU SAW A PORCUPINE?

More and more naturalists over a certain age are realizing how few porcupines they’ve seen over the last 30 years. Dawn Stover, a naturalist, freelance reporter and writer on the Columbia Insight, echoes this sentiment. She shares that her research on Porcupines  grew out of a personal interest living in Southwest Washington for many decades. Echoing the experience of other citizen scientists, ecologists, and naturalists, she “used to see porcupines fairly often, unfortunately, mostly as roadkill, but also live.” But it dawned on her that it’s been over 20 years since her last sighting. 3 Funny enough, Cascadia Wild has never detected a Porcupine on a trail camera survey in the Mount Hood National Forest. 

Dawn found that wildlife biologists are aware of the declining porcupine population and the evidence supporting this finding is growing. 

​In 2021, Humboldt State University graduate, Cara Appel and a team of researchers, conducted a study on Porcupines and found that porcupine populations may be declining in the Pacific Northwest and other areas. They began by compiling confirmed occurrences of porcupines in Washington, Oregon and northern California and comparing the findings from  1981 to 2010 with those from 2012 to 2018. “They saw a decline in most areas across the region.”3

​

Photo by Laurie Snell on Unsplash

3 theories about why the
porcupine population in
​Oregon is Declinging. 

THEORY #1 - "PLEASE KILL PORCUPINES"

Porcupines are considered pest species and there are many examples of government sanctioned lethal control dating back to the late 18th century. Settlers did not like porcupines interfering with commercial lumber activities. One tree that porcupines are especially attracted to and that exemplifies this reality is the Ponderosa pine, which is an extremely valuable, soft wood that can be used in a variety of markets. Ponderosa is abundant on the East Cascades where there have historically been lots of Porcupines as well. Unfortunately, from the late 19th century up until the 1980s, it was common practice for businesses, agencies, and industrial forest product companies to fatally poison porcupines in order to protect their crops. And it is still happening today.

THEORY #2 - Slow to reproduce.
Porcupines take a long time to reproduce. They are slow animals in general, but it takes 2-3 years for a female to reach sexual maturation  and, most importantly, they usually have only one porcupette each year. Obviously porcupines have been around for thousands of years and have survived perfectly fine with a low reproductive rate. However, some theorize that the anti-porcupine campaign combined with their slow reproductive rate indicates that they may have not had time to recover from being prosecuted.

THEORY #3 - Watch out for Fishers and Cougars!
Porcupines are primary consumers—relatively low on the food chain with many predators, including birds of prey, wolves, coyotes, and wolverines. Porcupines can usually escape through the protection of their quills and by climbing trees. Unfortunately, cougars and fishers are another story. These predators have mastered hunting porcupines and have tactics to force them out of trees. The cougar population in Oregon and Washington has exploded, and the return of fishers to the PNW may spell doom for an already struggling porcupine population.​

FUN FACT: Porcupines are only sexually active for about one month annually (around late August), and with all those quills, mating must be difficult!

YEs, The Porcupine Population Has declined.

Studies conducted by researchers like Appel et al. affirm the anecdotes of naturalists who haven’t seen a porcupine in a while. The Porcupine population has declined over the past 40 years, according to the Humboldt State University study. Currently, Porcupines are listed as “unprotected mammal” in Oregon, meaning that under Oregon law there are no closed seasons or bag limits, although a permit is required for hunting. It also means that orchard owners or logging businesses are entitled to take lethal measures to control Porcupine populations. Begging the question, do porcupines need legal protection?

Unfortunately, porcupines are understudied, and we don’t have enough proof to justify protections in Oregon. However, people are taking notice of their absence and that is inspiring more studies of this species. Accounts of decline come from naturalists who remember seeing more porcupines at one point in their lives and are now concerned about their absence. To me, this exemplifies the importance of naturalists and people connected to the land. Together, we can observe environmental changes and help collect vital information about our impact—or the impact of species like porcupines, whose ecological role isn’t fully understood. Considering they are a primary food source for animals like fishers and help create habitats by shaping trees, scientists are worried about what their absence could mean for the Pacific Northwest.

CITATIONS HERE.