American Goldfinch (Spinus tristis) Back After Absence

Male goldfinch in breeding plumage stops by for a drink.
Photo by Brad Sylvester. Copyright 2010. Do not copy.

In the winter of 2010-2011 and the spring and summer of 2011, we had a decided absence of American Goldfinches (Carduelis tristis or Spinus tristis) despite having had many of these colorful little birds in previous years. I am very happy to report that they are back this winter. They have been visiting our thistle feeder in good numbers for several months and appear healthy.

The goldfinch is one of the more brightly colored summer birds that visits our backyard feeders. They are also quite vocal and their twittering can be heard from the trees surrounding our yard as they prepare to swoop in on the feeder and take their turn.

American goldfinches swarming a thistle feeder in February.
Photo by Brad Sylvester. Copyright 2012. Do not copy.

As the regular author of a bird watching column for Examiner.com (Manchester Bird Watching Examiner) for the past several years, it seems like it's about time to start adding more of the birds that live in my yard to this blog. There are well over 200 species of birds that live at least part-time in New Hampshire. Even excluding seabirds and those with specialized habitats, I should be able to log a very large number of species in my yard. Birds should be second only to insects and possibly spiders for total species counts by my estimation, at least until we start considering microfauna.

Although American goldfinches may shift their range north or south with the seasons, they are always present as a species in New Hampshire and live in my yard year-round. They are active bird feeder visitors, preferring thistle seed to all other offerings. Although they pair up for the summer breeding season, in winter they tend to travel in small flocks travelling around from food source to food source.

• Read more about the American Goldfinch's change from winter drab to summer gold  

The American goldfinch is sometimes called the wild canary because of its bright yellow color and small size.

Lifespan: The Cornell Lab of Ornithology lists the oldest known American Goldfinch at 10.5 years (as of 2007). Average lifespan will be much lower, but I could not find reliably consistent figures.

Habitat: Overgrown fields and forest edge

Diet: Primarily seeds including thistle, sunflower, birch catkins, but will also eat insects during breeding season

When is it here? American goldfinches are found in New Hampshire all year round.

Where does it go in the winter? In the winter, American Goldfinches may move south to avoid severe cold, but the summer and winter ranges have considerable overlap according to National Geographic Field Guide to the Birds of North America, Sixth Edition. In places like New Hampshire where there is significant snowfall, American goldfinches often "hang out" close to backyard bird feeders with thistle seed or black-oil sunflower seeds during the winter months.

Life-cycle: According to information published by the USGS Patuxent Wildlife Research Center, American goldfinches lay 4-6 eggs per clutch once or twice per season. The eggs are very pale blue, almost white, and take 10-12 days to hatch and the baby birds are ready to leave the nest within 11-17 days after hatching. Breeding typically takes place in July.

Notes: The American Goldfinch makes a small, cup-shaped nest in the forking branches of trees and shrubs. Nests are often made of thistle or milkweed silk and other plant material woven tightly. Nests are usually constructed between 10-20 feet off the ground, but may be higher or lower. The Cornell Ornithology Lab reports that brown-headed cowbirds will often lay their eggs in the nests of American goldfinches, but that cowbird chicks cannot survive on the diet of regurgitated seeds and die within days of hatching.

What eats American Goldfinches? Many animals eat small birds. One of the biggest predators is the house cat. Others include bobcats, foxes, martens, fishers, raccoons, hawks like the sharp-shinned and Cooper's hawks, and many others.

IUCN Red List Status: Species of Least Concern, population trend: increasing

American Goldfinch Taxonomy:
The taxonomy of the American goldfinch is interesting because the genus was actually changed in the mid-1970's. Originally classified as belonging to the genus Spinus, it was reclassified into the genus Carduelis with Spinus becoming a sub-genus. It common to see the American Goldfinch listed either as Spinus tristis or Carduelis tristis.
Kingdom: Animalia (animals)
Phylum: Chordata
Class: Aves (Birds)
Order: Passeriformes (Perching birds)
Family: Fringillidae (True finches)
Genus: Carduelis (formerly Spinus)
Species: tristis

A Bull Moose (Alces alces): The Biggest, most Dangerous Animal in my Yard

Yearling Bull Moose (Alces alces) with spike antlers taken
in my backyard on February 6, 2012.
Photo by Brad Sylvester. Copyright 2012.

Sometimes I have to go to great lengths to find the animals that live in my yard, but when a bull moose (Alces alces) walks through the yard within 50 feet of the house, it's pretty hard to miss. This moose is definitely male, because it has antlers. Female moose do not grow them at all. Bull moose actually shed their antlers and regrow a new set each year.

The little spiky antlers on this moose tell me that it is almost certainly a yearling moose. Yearlings may keep their antlers later in the season than their more mature brethren who may drop their antlers around December. February or even March is not too unusual a date to see such a young moose still carrying last year's beginner antlers. You can tell that these are antlers from the prior season rather than newly developing antlers by the lack of velvet covering over them. In the pictures, the antlers of the moose that was in my yard appear hard and bony.

Moose Antler Growth

Bull moose showing developing antlers with brown velvet
feeding on aquatic plants in Errol, NH in July, 2011.
Photo by Brad Sylvester. Copyright 2011.

They would start out as buds around the end of April and begin growing with a brown, fuzzy covering called velvet. The velvet peels and gets scraped off on trees to relieve the itching as the antlers get ready for rutting season. The picture below shows a bull moose in July with his antlers coming in. The velvet shows clearly. You'll also notice that even though they are not nearly finished growing for the season, they are clearly going to be much, much fuller than those of the moose from my yard. This shows that the bull moose in the picture I took last summer in Errol, is older. You can see the full video of this adult male moose eating here. According to the New Hampshire Fish and Wildlife Service (NH F&G), the antlers of a mature moose may weigh 40 pounds.

Bear Killers

Even though it is still young, the yearling moose stands 6 feet tall at the shoulder and about eight feet tall overall. Moose are big animals. Already, this moose weighs more than a typical full grown black bear. During the fall mating season when it is full of hormonal aggression, it is also more dangerous than a black bear. The most dangerous moose, however, is the female with a young calf. They are fiercely protective and can not tolerate any creature physically getting between them and the calf. The NH F&G website claims that female moose have been known to kill not only people and black bears, but also the larger grizzly bear while defending their calves. These are very dangerous animals.

Although a female moose isn't as big as a male, an average adult moose weighs 1000 pounds and big bulls may go as high as 1500. The North Country News says that the largest female moose taken by hunters in New Hampshire was about 1100 pounds estimated live weight, while the largest bull taken in the Granite State would have tipped the scale at an estimated live weight of 1400 pounds.

Bull Moose trotting off down into the forest in my
backyard.
Photo by Brad Sylvester. Copyright 2012.

That makes the moose the biggest wild land animal not just in my yard, but in all of New Hampshire by a wide margin although cattle may weigh more. Despite its great size, moose are vegetarians eating leaves twigs and buds of trees during the winter and aquatic plants during the summer. Their noses close up to prevent water from getting in while they stick their heads underwater to graze.

There is a large marshy area in the valley below my house, perhaps a mile and a half away. This would be ideal summer grazing territory for moose while the forests make good winter habitat. Moose are excellent swimmers. Having watched one swim across a lake, I think I'd be pretty hard-pressed to out swim a moose for very long. On land, however, there's no question; the moose easily wins with a running speed that can top out around 35 miles per hour.

Moose Scat



Old moose scat from the woods at the back of our property
Photo by Brad Sylvester. Copyright 2011.

 About a month ago, I found moose scat down on the back part of my property, but it appeared to be at least a year old. Because it contains mostly woody material from the moose's winter diet, moss was actually growing on it. It looks a bit like compacted sawdust. Each pellet is about an inch long, much bigger than deer pellets. When we first moved here about 4-5 years ago, I saw a very young moose crossing the road about five miles away and we have seen moose tracks in the snow within a mile of our house, but this is the first time we've seen a moose on our property. Here's a video I took of a very young moose with its mother in Northern Maine.

The two depressions behind the print on the left are from
the dew claws of the hind foot of the moose.
Photo by Brad Sylvester. Copyright 2012.

After giving the moose in my yard a head start of about an hour, I followed its tracks through the woods in my backyard for over a mile onto a neighbor's property and into a protected wilderness area on the other side of that. I was curious to see where it went, but couldn't devote the entire day to following it; perhaps another time. I did find one hair from the moose's coat stuck on a tree branch that it pushed aside as it walked through the forest. You can see from the photo below that it is much thicker than a human hair placed next to it for comparison.

Moose tend to be solitary creatures. With the exception of mother and calf, and during the rutting season (mid-September to mid-October), they will most often, though not always, be spotted alone.

Moose hair on right,
human hair on left.
Photo by Brad Sylvester.
Copyright 2012.

Moose Tracks

Moose tracks are also big. They tend to have obvious dew claw marks in the snow, especially on the rear feet. The tracks from the moose in my yard measured six inches long without the dew claws, nine inches with them. They were 5.5 inches wide. Like deer prints, if the moose is running or trotting then the front part of the hoof will tend to be splayed open with more space in between the two halves.



The red arrows point to the dew claws at the back of
each hoof. The dew claws of the rear feet tend to show
up more prominently in the moose tracks.
Photo by Brad Sylvester. Copyright 2012.

 The stride of this moose varied from about three feet to about seven feet between prints depending upon the speed at which it was traveling. The rear prints tend to fall directly on or very near the front hooves, leaving a track pattern not unlike the one that a person would leave with left and right prints alternating.

Quick Facts about the Moose (Alces alces):

Diet: Moose eat twigs, leaves and buds from trees, especially during the winter. In the summer, they prefer grazing on aquatic plants pulled form the bottoms of shallow lakes, rivers and marshes.

Habitat: Forest and marshland.

When is it here? The moose lives in New Hampshire all year round, but may move from forest to marshland depending upon the season.

Home range: From 1-25 square miles according to NH F&G.

Where does the moose go during the winter? The moose will forage in the forest or at the forest edge during the winter. It is not bothered by cold, unless its coat is damaged or worn off by scratching (such as might be caused by a tick infestation).

Life Cycle: Moose mate from mid-September to mid-October. 1-2 calves will be born in late May or early June. The calves are cared for by their mother for about a year. Females are ready to mate during their first year while bulls take a few years to grow big and strong enough to challenge for the right to mate by clashing antlers with other rutting males.

Moose Lifespan: Moose typically live 10-15 years.

Moose taxonomy:
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Artiodactyla
Family: Cervidae
Subfamily: Capreolinae
Genus: Alces
Species: Alces alces

To catch a deer mouse (Peromyscus maniculatus)

Notice the bicolored tail, dark above, white below, on the
deer mouse (Peromyscus maniculatus)
Photo by Brad Sylvester. Copyright 2012.

There are a number of different species and subspecies that are popularly called deer mouse, wood mouse, or white-footed mouse. Many have a similar appearance and if you just catch a glimpse of one or are just looking at a top view as it sits in a bucket waiting to be carried far away from the house, then it can be hard to tell the difference between them. This appears to be a deer mouse of the species Peromyscus maniculatus.

One of the best websites detailing the differences between the deer mouse and similar species is enature.com. The tail is one key point of identification. In Peromyscus maniculatus, the tail is dark above and light below. There’s a clear demarcation of the two colors on the tail which should be about the same length as the rest of the mouse. The bicolored tail is shown clearly in the photo at the top left of this post.

The white underbelly with the tail details, the color of the top of the mouse’s body, the large, bulging eyes, and the location where it was found (New Hampshire) make it a pretty sure bet that this is, in fact, Peromyscus maniculatus, even though there are four species of mice that are native to New Hampshire and one (the house mouse – Mus musculus) that was introduced from Europe and is now firmly established here and throughout North America . If you look up images of the species by the common name on the Internet, however, odds are about fifty-fifty that you’ll get something other than Peromyscus maniculatus.

Deer mice typically live in the forest and fields and do quite well without coming into human houses during the winter. They will burrow under the snow seeking seeds and other edible plant material. In my yard, they will eat the soft green bark of bushes and shrubs below the snow so the damage isn’t visible until the snow melts in the spring. Once the snow does melt, however, the gnaw marks are very clear often girdling the bush (removing the bark all the way around it), which kills the plant.

From the top, not enough distinguishing features can be seen
for a positive identification of the deer mouse (Peromyscus
maniculatus).
Photo by Brad Sylvester. Copyright 2012.

We do, however, get an occasional mouse inside the house when there is a period of particularly cold or severe winter weather. They come in seeking better shelter and a more ready source of food.
Mice are prolific breeders. Just a couple slipping into the house can turn into an infestation if not quickly eliminated. Once inside, they’ll also look for whatever foods they can find there: dog food, cat food, my food.

For that reason, and because the area in which we live has carpenter ants which would like nothing better than to chew up the structural wood of our house until it falls down around our ears, our house is serviced regularly by an exterminator. They bait for rodents in the crawl spaces and little nooks and crannies where they might be otherwise found. This is quite effective and we generally don’t have mice around, at least not for very long.

Outside, however, there are the tunnels in the snow that reveal their presence and favored routes. To catch one, I just needed to put this live capture mouse trap , baited with peanut butter, in the walkway near the opening to one of the snow tunnels.   That's what led to the photo opp. for this little guy. This deer mouse was released unharmed.

Quick Facts about the Deer Mouse (Peromyscus maniculatus):

Diet: The deer mouse eats seeds, insects, berries, nuts and mushrooms. The US Forestry Service doesn't list the green inner bark of shrubs as part of the deer mouse diet, but I have the dead ornamentals to prove it, although they don't seem to choose it when other food is available in the summer. Since they seem to only eat it when it is under the snow, it is hard to catch them in the act. In this case, however, the tunnels, footprints, and captured deer mouse itself provide pretty solid evidence that this is the species that is eating the bark. 

Range: According to US Forestry Service, the deer mouse lives pretty much all throughout the continental United States except the extreme southeast (northern Georgia yes, Florida no). It can also be found in parts of Mexico and Canada west to southeastern Alaska.

Habitat: Deer mice live in just about every type of habitat: forests, fields, scrub, canyons, desert, you name it. They build nests just about everywhere, too. Deer mouse nests can be found high in trees, in underground burrows, in scrub piles, rock piles, and all sorts of man-made structures (like houses, cars, and barbecue grills) where they can stuff leaves, grass and other soft insulation to make it more comfortable.

Reproduction: Litter sizes may range from one to nine, but three to five is more typical. Gestation lasts 22-26 days and females may have several litters each year. The US Forestry site says that as many as 14 litters in a single year have been reported. At about 48 days of age, female deer mice are sexually mature and ready to begin having litters of their own.

When is it here? The deer mouse is a year-round resident of New Hampshire.

Where does it go int he winter? The deer mouse does not hibernate and is fully active throughout the winter.

Territory:

Predators: What eats deer mice? Many New England animals eat deer mice. The owl, coyote, fox, bobcat, house cat, snakes, weasels, martens, fisher cats, mink, chickens, and even skunks will all eat deer mice either regularly or opportunistically. With so many predators, the deer mouse relies on frequent litters and rapid maturation to maintain its population.

Deer Mouse Taxonomy:

Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Rodentia
Family: Cricetidae
Genus: Peromyscus
Species: Peromyscus maniculatus


Sourcing Note: Because the range of the deer mouse covers such a wide variety of climates and geography, there are variations in reports of diet, litter size, litter frequency and other aspects of behavior among different sources. They may all be correct for different regions, but I have used data from the US Forestry service website linked above for information that I have not directly observed myself.

Ruffed Grouse (Bonasa umbellus), Popular Game Bird

A ruffed grouse (Bonasa umbellus) in a New Hampshire
birch thicket.
Photo by Brad Sylvester. Copyright 2012. Do not copy.

With several inches of hard, ice-crusted snow on the ground, ground feeders like the ruffed grouse (Bonasa umbellus) can have a hard time finding food. Fortunately, the upper branches of most trees tend to remain relatively snow free, especially if there's a little wind to knock the snow off. The ruffed grouse, therefore, can often be found in the treetops after a particularly deep snowfall or when the snow has frozen over with a hard crust. That's where I spotted this one.

This ruffed grouse is about 25 feet high in the trees, and was walking along the branch eating birch catkins. Normally, the ruffed grouse is a ground feeder, eating berries, buds, plant shoots, and fallen nuts that it finds there.

The ruffed grouse is a large bird measuring about 17 inches long with a plump, round body. As such, it is a favorite game bird of New Hampshire hunters. In fact, says New Hampshire Fish and Game, fully two-thirds of all the hunting hours logged by small game hunters were spent in pursuit of the ruffed grouse. Hunting season for the ruffed grouse in New Hampshire runs from October 1 through December 31 and requires a small game permit. I don't hunt myself, and generally don't allow hunting on my property as I enjoy the presence of the animals that live here.

When I first moved to our home in New Hampshire, I would often hear a strange, low-pitched noise coming from the woods. It was a slow thrumming sound that increased its pace over the course of about 15 seconds before stopping. It was the call of the male ruffed grouse. Actually, not a call, but rather the sound the bird makes during it territorial display, flapping its wings at an increasing pace moving its wings so fast with each flap that the sound of air rushing to fill the void left by the moving wind makes a loud, low pitched sound almost like a hushed drumbeat.

Unfortunately, I haven't heard this sound from the woods behind my house for the last two years. Either the male ruffed grouse that was there has moved or died. There is, however, a female that still resides in my yard. Every so often when I am walking through the woods, I will inadvertently flush it out and catch a brief view of it as it wings away from the perceived threat. I try not to startle it or go to areas where I know it hangs out, but it sometimes feed next to a walking path that I use.

Ruffed grouse prefer to live in areas of thickly growing small trees. Aspen is their favorite, but other species will do. The thick growth of small trunks gives them cover from predators and provides a source of food. In my yard, there is a decently-sized area of successional birch growing too thickly for a person to comfortably walk through. This is perfect home territory for ruffed grouse and it is in or near this area that I typically find them.

 

Quick Facts about the Ruffed Grouse (Bonasa umbellus):

Where does it live? The ruffed grouse lives in the forest and makes its nest on the ground. Depending upon the food availability in a given year, a ruffed grouse requires a range between 4-40 acres per bird. Females tend to be more mobile feeding throughout the ranges of several males during the winter. They range through most of Canada and the northern United States.

Diet: Plant buds, fruit and berries, young plant shoots according to Birds of Eastern North America: A Photographic Guide. It's hard to imagine, though, that they won't take forest beetles and other insects as opportunity presents.

Where does the ruffed grouse go in winter? The ruffed grouse stays right here all year round and does not migrate, although as I mentioned above, it's feeding habits may change when its usual dining table, the forest floor is made inaccessible by snow.

IUCN Red List status: Species of Least Concern, however, the IUCN notes that although it does not meat the threshold of vulnerable due to its wide range and population size, the population trend of the ruffed grouse is declining.
Breeding: According to the Natural Resources Conservation Services of Minnesota, the ruffed grouse hen lays 9-14 eggs over about two and a half weeks and then incubates them for 23-24 days before they hatch. Like chickens, the hen doesn't start incubating the eggs until the nest is full. Until then, the eggs remain in a dormant state. That allows all the eggs to hatch at about the same time. Although they will follow the mother hen around for 8-12 weeks, the ruffed grouse chicks are able to feed by themselves as soon after hatching as they get hungry. The mother, however, provides protection from predators by attempting to draw attention away from the chicks if a threat comes too near.

Ruffed Grouse Taxonomy:

Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Galliformes
Family: Phasianidae
Genus: Bonasa
Species: Bonasa umbellus

2012 Plans for What Lives in my Yard?

It’s the start of the new year and a good time to fill you in on my plans for this blog for 2012. First, I’m going to continue doing what I’ve been doing, but step up the pace and add a minimum of 120 new species to master list this year, each with individual blog entries. So far, I have just one for 2012. It’s certainly a whole lot easier when the ground isn’t frozen and covered with snow (with some exceptions), so I will catch up.  I also want to invest more effort into observing animals for extended periods of time to learn more about their habits and behavior in the wild. I also want to do some new things with the blog this year to make it even more interesting.

New Traps and Collection Techniques for 2012

In 2012, I’ll also use several new insect trapping/ gathering techniques and provide step-by-step instructions as I did in 2011 with the insect pit trap. Some of these techniques can yield hundreds of specimens of dozens of species with just a couple of hours of work. I may also use a larger pit trap to see if I can catch some small forest floor mammals and reptiles.

Aquatic Creature Collection

When it’s much warmer out, I’ll start poking around in streams and vernal pools to see what we can find. With some luck, we’ll find aquatic eggs that we can watch hatch with video or time-lapse still pictures.

Find More Lizards and Snakes

I don’t have any salamanders or lizards on the list yet, but I’m pretty sure there must be several species of them that can be found in my yard. I also like to find a few more species of snakes to add to our list.

Capturing Metamorphosis

I’ll also be keeping a few of the caterpillars that I find, especially those that are hard to identify, to let them turn into moths or butterflies in captivity to help with the identification, again with complete instructions how you can do that at home or at school. When I do this, I’ll go into more detail about the process of metamorphosis and how it differs for a variety of different animals. Hopefully, I can get some time-lapse photos taken and make a video to show the full process.

Identifying Animal Tracks and Signs

At some point this year, I hope to add some pages here dedicated to identifying animal tracks and scat with pictures, original line drawings, and tips to help figure out what animal left any tracks you might find. We’ll also used other left-behind clues like feathers, abandoned bird’s nests, egg shell fragments, and shed skins to help figure out who lives in my yard.

Finding Animal Homes

Whenever we start getting too close to the place where an animal makes its home and raises its young, we run the risk of stressing the animal or even driving it off. To see them in these places, we need to use great care to avoid any possibility of disturbing or harming the animal in question. Fortunately, in this age of technology, things like remote cameras can give us a candid look into places like a bird’s nest without bothering the animals at all, especially if we place the cameras before the bird or other animal ever arrives, such as with nest box cameras.

Bring in Real Animal Experts

This year, I hope to also spend some time talking with real animal experts who can shed some light on areas in which I lack expertise. I’ll find some experts to help with the tricky identifications, talk about habitat management, biodiversity, tracking, animal behavior, natural history, and other related topics and share that here on the blog this year. For some of the creatures that live in my yard, I’ll supplement the pictures I take here, with visits to rehabilitation centers, zoos, or university research centers or other places where I might get better access for photos and observing the animals in question.

Your Ideas?

What else would you like to see here? What do you like or not like about “What Lives in my Yard?” Let me know in the comments section below. I read them all.

Porcupine Dens in my Yard Confirmed by Trailcam

A porcupine heads out for a snack in the dark of night. The
grizzled white areas on it's back and tail are the areas of
heaviest quill concentration.
Photo by Brad Sylvester. Copyright 2012, Do not copy.

In my previous entry, I wrote about a path of footprints leading out from two holes in the ground in the forested part of my yard. Well, for each of the last two nights, my trailcam has captured pictures of the creatures that are using the underground dens to escape the winter cold. As I suspected, they are porcupines or taxonomically speaking, Erethizon dorsatum.

The resolution of the camera is not high enough to tell for certain how many individuals are living in the dens, but from size differences of those porcupines photographed, I would say there are at least three. At least one is much smaller than the others and was probably born this past summer. I have known that porcupines lived on my property for some time, but I did not know they had a den here. Indeed, it may be only a temporary den for the winter as I have never seen tracks or other signs of porcupine occupancy there prior to last week.

Although generally nocturnal, it's not too unusual to
see procupines during daylight hours. This one, shown
disappearing into its den, was active in the middle
of the afternoon.
Photo by Brad Sylvester. Copyright 2012. Do not copy.

Porcupines are generally nocturnal feeders, but can be found out and about during daylight and dusk from time to time as well. As I mentioned last time, they don't hibernate or even fall into a winter torpor. Their thick coating of hair and quills provide them with insulation and there primary foods are available all year round.

Porcupines can cause terrible injury in dogs or any animal that attempts to touch them, but they are one of nature's best examples of a passive-aggressive creature. Porcupines respond to threats by turning away and slowly walking off as if they have no care in the world. In reality, their tails and backs are where their quills are thickest. Any attack from the rear is almost certain to result in more pain and injury to the attacker than to the porcupine. If the attacker gets too close for comfort, the porcupine will flick its quill-covered tail at them and do its best to turn the attacker into a pin cushion.

Porcupette Video. Copyright Brad Sylvester 2012

Porcupine quills have a very sharp point at the end and have small, scale-like barks that prevent them from being easily backed out once the penetrate the skin. Instead, they actually work themselves deeper over time. Porcupine quills can be quite painful and may result in serious infections if not removed and the wounds treated.



A porcupette looks down from an overhead branch. The
rodent's chisel-like incisors are visible.
Photo by brad Sylvester. Copyright 2010. Do not copy.

 Despite this defensive armament, the porcupine does fall victim to several New England forest predators on a regular basis. The most accomplished porcupine hunter is probably the fisher cat. I've been told that fishers attack porcupines in one of two ways. They'll harry the porcupine using their own speed and agility to stay out of reach. The fisher attacks the porcupine's head until the porcupine is completely exhausted (or dead) and can no longer turn its back fast enough to defend itself. Then the fisher will flip the porcupine over and eat from its unprotected underside. Another technique is to attack a treed porcupine from below as it clings to a branch. From that angle, its unquilled belly is exposed. I haven't seen either of these behaviors to confirm these modes of attack, but that's what folks around here say.

Trailcam video. Copyright Brad Sylvester 2012.

Bobcats and coyotes are also known to kill and eat porcupines as well. The head is largely undefended and frontal attacks against the porcupine are the least dangerous for the attacker. We have all three porcupine predators in New Hampshire and both bobcats and coyotes have been present on my property on more than one occasion since I moved here in 2007.

Quick Facts About the Porcupine (Erethizon dorsatum)

Size: Porcupines are the second largest rodent in North America. Only beavers are bigger. Adult male porcupines can weigh 35 pounds or more, but 12-15 pounds is a more common adult weight. Porcupines may measure more than three feet long and over a foot tall at the shoulder.

Lifespan: up to 15 years in the wild

Diet: Mainly the soft inner bark of trees, young evergreen needles, and plant buds. Hemlock is a favorite. In the spring and summer, porcupines will also eat grass and other green plants, fermenting fruit, seeds and some tubers. They are also known to chew treated wood or even rubber for the salt and mineral taste and may become a nuisance by eating the bark of fruit trees, sometimes girdling branches or the trunk and killing them. As a child, I remember hiking the Long Trail in Vermont and often finding porcupines chewing away contently at the wooden lean-tos built along the trail by the Forestry Service.

Where does it live? Porcupines live throughout the northern United States and Canada. According the IUCN information page, it can also be found further south in the west, even into northern Mexico.

Habitat: Porcupines most often inhabitat mixed forests, but in the spring can be found feeding on grass in open fields, especially when they are caring for a young porcupette. In the southwest, says the IUCN, they may live in desert scrub. Further north, they also live in the Canadian tundra.

When is it here? The North American porcupine lives in New Hampshire all year round?

Where does it go in winter? No place special, the porcupine does not hibernate or fall into a winter torpor. If the weather is especially cold or severe, they may form communal dens for a time during the winter, leaving each night to feed.

Breeding: Porcupines mate from September to December. They give birth usually to a single baby about seven months later. Males often fight viciously and noisily over females during mating season.

IUCN redlist status: Species of least concern. Wide distribution and large population.

Notes of interest: Each porcupine has over 30 quills. Baby porcupines are called porcupettes. Porcupines are very good climbers, but slow and awkward on the ground.

Porcupine Taxonomy:
Phylum: Chordata
Class:  Mammalia (Mammals)
Order: Rodentia (Rodents)
Family: Erethizontidae
Genus: Erethizon
Species: Erethizon dorsatum

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Update: My new YouTube channel: @WhatLivesinmyYard talks about the porcupine in Episode 1.

Hole in the ground becomes winter den

This hole goes as deep as I can see, twisting around
underground boulders. Now it appears that porcupines are
using it for a winter den.
Photo by Brad Sylvester. Copyright 2012. Do not copy.

During the summer, I found a deep hole in the ground in my backyard forest. It's right at the base of a tree and if you peer into it, you can see about six feet down although there are numerous very large stones (two foot diameter or more) causing the hole to twist and turn as it descends. It seems to go much deeper. At any rate, it's well below the frost line for New England which is somewhere just under three feet as I recall from my study of architecture in high school.

Two days ago, we had about three inches of snow and I happened to walk through the part of my yard where the hole is. There was a very well-trod path coming out of the hole and proceeding about 15 feet to another similar, but smaller hole, in the ground. From there, the path continued on and split. One fork went to the base of a nearby pine tree, straight to the trunk. From the tree, it appeared as though it came straight away from the trunk and continued into the forest.

The tracks seemed to show that the path went up the tree and came back down before continuing. The paths were very well traveled as I mentioned. So, it was impossible to make out individual prints to see what creature or creatures had made the trail. There was no scat or other evidence to help determine what might be using the dens.

Today, I went back to install my trail cam in a position to catch photographs of whatever it is. There was new evidence. Urine and scat right outside the holes in the ground suggested that it might, indeed, be what I suspected. A communal den of a fairly common New England mammal that does not hibernate in the winter: the porcupine.

Communal Porcupine Dens

Second suspected porcupine den located just 15 feet from
the previous one. One trail leads to the other opening,
and one leads further into the forest.
Photo by Brad Sylvester. Copyright 2012. Do not copy.

Porcupines generally have solitary or family dens, but in periods of severe winter weather, they may group together in a single den which benefits them all by the sharing of the communal body heat. I believe these two holes in the ground are communal porcupine dens. Today, I placed my trail cam in a position where it will almost certainly get some good identification photos of whatever is spending its days in these holes.

Which brings us to the question of why don't porcupines hibernate or go into a winter torpor like so many other small mammals. I would guess that it has to do with the preferred diet of porcupines. They eat the small, tender twigs of evergreen trees, green bark, and the young evergreen needles. They especially like hemlock. Of course, as the name says, evergreen trees stay green and full of porcupine nutrition throughout the winter. There is no need, therefore, for a porcupine to shut down its metabolism and wait for the new growth of spring. They will also eat fallen fruit when it is available.

Signs of Porcupines

As an aside, there are two sure signs of porcupines. First, lots of bits of the ends of hemlock branches littering the forest floor under the tree. The porcupine climbs out on the branches to eat the small twigs and to reach the newest needle growth. It eats the needles from the small twigs, but as it does so, the branch tips are discarded and fall to the ground. Porcupines, being both lazy and creatures of habit, will revisit the same few trees over and over again around its den, relying on the growth of those trees, especially during the spring and summer months to keep the porcupine's plate full.

Porcupine Droppings
The second sure sign of porcupines, is an excess of droppings outside of a ground level tree hollow, small cave or other suitable den entrance. Porcupine's are not meticulous about the placement of their droppings. Very large piles of droppings of varying ages will, therefore, accumulate outside the entrance to a porcupine's den over time. As they walk through it several times a day, trailing their dragging tails and quills, they will form a stained trail into and out of the den. On the positive side, the scat is made up almost entirely of undigested cellulose lacking in strong odor. Procupine droppings are a bit like rounded, oblong deer droppings, but tend to have a pronounced curve, making them almost "C" shaped. Other than outside the den where they accumulate, they'll be present in much smaller piles than deer droppings, or even individual pellets.

A trail leading straight into a tree trunk and then away
indicates an animal that climbed up the trunk such as
a squirrel or porcupine. These tracks are too big for
a squirrel.
Photo by Brad Sylvester. Copyright 2012. Do not copy.

Porcupine Winter Behavior

As long as a porcupine can withstand the cold temperatures or winter, they can find plenty of food to sustain them even in the deepest snows of winter. By grouping together during the coldest weather body heat of many porcupines is combined to raise the ambient temperature of a den, which may be underground or in a large tree hollow. Together they can keep the temperature in the den much higher than any individual could by itself. That means fewer calories need to be burned to stay warm. In extreme conditions, it means the difference between surviving and freezing to death.

Of course, when it comes to the "whys" of animal behavior, we can only make assumptions based on the available evidence. There may be some other reason for communal dens during the harshest part of the winter, but Occam's Razor says that we should first assume the simplest explanation is correct until additional evidence disproves it.

I'm actually very excited to find dens of any mammal in my yard because it offers the possibility of regular and close observation of the den's occupants to learn more about their behavior than I might learn by simply catching pictures of them visiting feeding stations or walking along a common game trail.

Hopefully, one or more of the porcupines, assuming I am right in my guess of the occupants of these dens, will choose to raise offspring here in the spring. That opens up the possibility of me putting a remote camera inside the dens in addition to a camera outside the den to observe the kits as they develop.

I can hardly wait.

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Update: My new YouTube channel: @WhatLivesinmyYard talks about the porcupine in Episode 1.