Monday, November 17, 2014

Porcupines: Wayfaring Wildlife

Porcupine by Mary Harrsch (Wikicommons)Big game hunters and auto body repair shops know well that early to mid November is the time in the Adirondacks when deer are on the move; however the white-tail is not the only creature that breeds during late autumn.

The porcupine also develops its urge to reproduce in the period between Veteran’s Day and Thanksgiving. As is the case with deer, older male porcupines are currently on the move in their attempt to locate as many females nearing their estrous period as possible over these next several weeks.

Unlike the beaver and red and gray fox which establish a pair bond with only one individual, the porcupine, like most mammals attempts to breed with as many members of the opposite sex as time and opportunity allow. As she becomes receptive, a female engages in a courtship ritual with any older and larger male that happens to encounter her. If the male were to depart shortly after breeding, she may elect to mate again if another suitor were to arrive while her hormones still influenced her behavior. This is why a male typically remains in the immediate area after breeding so as to attack and fend off any male attracted to the smell of her scent. This helps ensure that only his genetic material goes into the fertilization of her egg, perpetuating his blood line. After the female loses her desire to breed, the male quickly abandons her and continues his travels to search for additional females in need of a mating partner.

In order to greatly reduce the chances for inbreeding, 2 year old porcupines, prior to sexually maturing, disperse well away from their area of birth. Female porcupines have been reported to engage in this relocation event during mid summer, a month or two after their 2nd birthday. (Like deer, the porcupine gives birth in late spring, usually in late May or during the first half of June.) This dispersal comes at a time of year when lush vegetation is abundant everywhere and any potential predators have their fill from the abundance of young, inexperienced small game creatures that have recently entered the world. The males typically develop their urge to vacate their natal home range at the end of the summer or during the first weeks after Labor Day. It is not understood why the females disperse before the males in summer, only that there is a month or two between the time when they travel in search of a suitable home range in which to live their adult life.

An analysis of highway mortality occasionally reflects these different time periods. A dead porcupine on the road during mid summer is more likely to be a 2 year old female than an older animal, and a victim of a car collision at the end of summer is more likely to be a 2 year old male. At this time of year, older males are the ones inclined to be killed, as these are the individuals currently on the move. In spring, as the snow pack is rapidly receding, any individual may be lured to the edge of a highway where road salt residue has permeated wooden objects close to the shoulder, occasionally resulting in death.

There are very few predators willing to attack a porcupine as it travels across the forest floor because of its highly effective covering of sharp quills. When confronted by an enemy, a porcupine initially warns an intruder of its identity as it raises these defenses weapons while turning its back to the potential attacker. As its quills are placed in an upright position, the white base and shaft of these barb-tipped needles becomes visible. This contrasts with its dark fur to create a visual image unmistakable to any forest dweller. Additionally, as it tightens its skin to elevate its quills, tiny glands on its lower back release a quick dispersing chemical that further identifies this rodent and indicates its potential danger. Finally, the porcupine rapidly taps its teeth together to produce a chattering noise, signaling its irritation. Because the porcupine is primarily nocturnal, it uses a combination of sight, smell and sound cues to forewarn other creatures of the night that an encounter would lead to a painful lesson and could prove to be fatal.

Some breeds of domestic dogs have not acquired this “survival skill” and will repeatedly attack a porcupine whenever the opportunity arises despite previous painful encounters.

Because the porcupine restricts its movements for much of the year, especially during winter when there is a significant accumulation of snow on the forest floor, road kill is not as likely to occur as during these travel periods. Similarly, if you have a dog as a pet, there are some time of the year when an encounter with a porcupine is more likely than others. Currently, older males are on the move, and this awkward-moving rodent can cover a fair amount of land every night as they search for romance, just as bucks are doing. When driving, please be especially careful at this time of year for deer and porcupines. Although a porcupine is substantially smaller, it can still do a fair amount of damage to a small vehicle if it impacts the car in the wrong spot.

Porcupine by Mary Harrsch, Wikicommons.

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Tom Kalinowski is an avid outdoor enthusiast who taught field biology and ecology at Saranac Lake High School for 33 years. He has written numerous articles on natural history for Adirondack Life, The Conservationist, and Adirondack Explorer magazines and a weekly nature column for the Lake Placid News. In addition, Tom’s books, An Adirondack Almanac, and his most recent work entitled Adirondack Nature Notes, focuses on various events that occur among the region’s flora and fauna during very specific times of the calendar year. He also spends time photographing wildlife. Tom’s pictures have appeared in various publications across the New York State.

2 Responses

  1. Jim S. says:

    I really enjoy learning more about our natural world on this site. Thank you for all the articles. I often use these articles to drop stupid puns,but I want you to know I truly appreciate your work. By the way,you brought up some very interesting “points” about porcupines.

  2. Charlie S says:

    What a beautiful specimen the porcupine. I see them dead on the roads all of the time in New York, Vermont, New Hampshire.I saw three of them dead on a road in New Hampshire recently, two right across from each other, the third about a quarter of a mile further down the road. A family of them wiped out! I saw one dead a few months ago on Locust Grove Road in Greenfield up in Saratoga County.(This was early-on in summer) I could not believe the size of this porcupine it must have been a great granddad. All of the years it took to get that size and ‘boom’ done in a mindless moment. There’s plenty of them going around….mindless moments.

    Locust Grove Road is one of those roads that cuts across old farmland in a straight line so that when you’re driving on it you can see a minimum of one mile ahead in some places. My understanding is that porcupines are slow-movers when they go over roads. This particular animal was the size of a small compact car.So how could a driver not see it? Maybe he or she was doodling with a handheld device at the time. Or maybe getting to point B was more important than a porcupine. Apathy?

    As with the pet Llama that was shot and killed recently by some misfit, or the Newcomb moose, and all of the other placid creatures who cross paths with dysfunctional humans…. this porcupine was just another victim to add to the ever-growing list whether it be highway mortality, gunshot, arrows or broom handles (I’ll spare everyone the grief on this one.)

    Thanks for the story Tom. It was good to be reminded of some of the misery I have witnessed.

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