Before joining Snapshot Wisconsin in 2016, I knew very little about porcupines. I grew up in Iowa where porcupines were extirpated in the 1800’s. What I knew consisted of what I learned from my grandparents as a youngster on summer fishing trips to northern Minnesota. Essentially, porcupines have sharp quills and you don’t want your dog to tangle with them. I never saw a porcupine on any of these trips but was always on alert to make sure my dog, a Miniature Schnauzer named George, never wandered too far.
My first task upon joining Snapshot Wisconsin was classifying photos from Black River Falls, where trail cameras are in place to monitor the reintroduced elk population. As I was flipping through photos, I kept seeing these critters that I couldn’t identify. They were small, rounded and dark colored, always facing away from the camera, and only appearing at night. I wasn’t sure what these could be, and we had yet to create resources to help with this task, such as the Snapshot Wisconsin Field Guide*. Sometimes I classified them as raccoons and sometimes as beaver (in my defense, our early cameras didn’t take very clear photos!) Eventually, my porcupine identification skills improved and thankfully so did the photo quality of our cameras. Porkies have since become one of my favorite species captured on our cameras. Read below to learn more about these quill-y, charismatic critters!
There is only one species of porcupine in Wisconsin, the North American porcupine (Erethizon dorsatum). Worldwide there are 23 different species of porcupines. Our porcupine is the second largest rodent in North America, only beavers are larger. Their size ranges from 7-30 pounds and 20-26 inches. They typically give birth to one young per year. Young are called porcupettes.
Porcupines are herbivores, consuming tree bark, branches, buds, evergreen needles, garden produce, and even tool handles.. A common misconception is that porcupines can shoot their quills when threatened. The quills are actually loosely attached and embed themselves in the unfortunate victim when they come in direct contact with the porcupine.
Porcupines occur in the Northern and Central Forest regions of Wisconsin. To date, we have had 4,175 reports of porcupine from trail camera hosts. These have not yet been verified and presumably include a few raccoons and beavers due to my early classification mistakes and similar errors by other staff and volunteers. A handful of porcupine classifications from southern Wisconsin (Grant, Iowa and Waukesha counties) revealed the true species to be woodchuck, raccoon, unknown bird and squirrel. Species distribution maps are quite useful for classifying our photos and Snapshot Wisconsin data will be instrumental in updating these in future.
Find out more about porcupines at the links below!
*Snapshot Wisconsin Classification Field Guide (located on the right hand side of your screen while classifying photos on Zooniverse)
Within the scientific field of animal behavior, research topics such as parental care, natural selection, and feeding tendencies seem to arise far more frequently than animal play. After all, a life in the wild tends to revolve less around play and more around survival. For some animals, however, play is an integral part of their lifestyles and ultimately their perseverance. River otters, for example, are social animals with a playful and charismatic reputation. As their name suggests, river otters do not typically stray far from waterways, and some Snapshot Wisconsin cameras are perfectly positioned to capture interesting otter behavior. We have observed otters grooming together, wrestling with one another, and – perhaps most amusingly for our staff and volunteers – sliding across the snow. At the bottom of this post there is a compilation of otter slide photos.
Undeniably, sliding across snow or mud is an effective method for locomotion when you compare it an otter’s normal gate – a cylindrical body bounding on short legs. It’s the kind of body shape that glides effortlessly through the water but doesn’t demonstrate the same sort of grace on land. Those proportions make it especially tough to traverse snow, just take it from the otter pictured on the right.
Is sliding truly just an efficient way to travel, or does the otter’s seemingly spirited nature play a role in this behavior as well? A 2005 paper published in the Northeastern Naturalist suggests that it could be both. The study analyzed 5 minutes and 49 seconds of video of wild otters in Pennsylvania. The otters were observed sliding 16 times, an excessive number for the sake of conserving energy.
The term “otter slide” doesn’t just refer to a mode of transportation, however. It can also refer to the marks near riverbanks that are left when otters slide in and out of the water. Often repeated otter sliding will occur near latrine sites, where the animals will go to deposit and read scent-coded messages from other otters in the area. The slides are such a great indicator of otter presence, that the Wisconsin DNR conducts aerial surveys in the winter to help determine population trends. Whatever the motivation is behind the sliding behavior, we certainly enjoy watching it on our trail cameras.
Did you know that white-tailed deer (Odocoileus virginianus) antlers are one of the fastest growing tissues known to man? For instance, human fingernails grow between 1 to 10 centimeters a year whereas white-tailed antlers grow several centimeters each day during the growing stage! Unlike human fingernails, deer antlers are composed of veins, arteries, vessels, and cartilaginous tissue. Many hunters believe that the bigger the rack the older the buck. Yet, the inspection of teeth is the only accurate indication of a deer’s age. The greatest antler size within a buck’s life is from age five to seven. Factors sure as age, genetics, and nutrition of the buck determines the magnitude of antler size. Keep reading below to learn how antlers grow and change throughout the year!
Pedicles, the area attaching the antler to the skull, are first formed on top of a buck’s head during late winter and spring and can reach up to ¼ of the ear-length. Snapshot Wisconsin asks volunteers to classify any deer with formations less than ¼ of the deer’s ear-length as antlerless, while reserving the antlered classifications for more than ¼ of the deer’s ear-length.
To create antlers in early spring, minerals in the ribs and shoulders of the buck are redistributed in his body. Velvet (pubescent skin) covers the antler and provides nutrients through the flow of blood. These nutrients cause antler growth. During the velvet stage, the antlers are very sensitive. Any impact will be painful and could, due to the fragile state, cause breakage. Nevertheless, this sensitivity allows the buck to comprehend the size of its antlers and, eventually, the buck will move through the forest with ease.
By late summer, the antlers are fully grown. Blood flow becomes constricted, causing gradual hardening and calcification. The velvet dies off in response and, like a sunburnt human, the buck becomes annoyed and wants to peel the excess skin off. The buck rubs his antlers on trees to rid himself of the velvet, exposing glabrous antlers. This rubbing strengthens the buck’s neck, which will come in handy during the rut where the buck will compete with other bucks’ antlered attacks.
Due to reduced sunlight and testosterone, white-tailed bucks’ antlers fall off around January and February. Their body absorbs the calcium between the antler and pedicle, which weakens the antler, causing it to eventually fall off. If you’re looking for a hobby this time of year, check out shed hunting! Shed hunting is the pastime of searching for antlers that have been naturally shed by antlered bearing mammals. Another great hobby for this time of year is checking out the trail camera photos captured by the Snapshot Wisconsin project! Start viewing and classify photos today!
For more information, please visit these sources:
If you are familiar with Snapshot Wisconsin’s crowdsourcing website hosted by Zooniverse, you likely have heard of the term #SuperSnap used by volunteers to denote especially captivating photos. Recently a slight typo, #SuperNap, not only gave Snapshot staff members a good laugh – but also a potentially catchy new phrase for hibernation? In this blog post, we will dive into the science behind slumbering wildlife in winter.
What is hibernation?
When winter rolls around, critters get creative with how to stay alive! In some cases, animals combat the considerable metabolic challenges of winter by entering into a state of temporary hypothermia, such as the black-capped chickadee. The ruby-throated hummingbird migrates south to Central America to avoid the entire winter thing all together. Others avoid the perils of induced hypothermia and the exertions of migrating by going to “sleep”, or hibernation. During this state of sleep the temperature, breathing rate and heart rate of animals drops significantly. To survive harsh winter conditions and scant food availability, animals can quite literally shut off for a few weeks at a time. If you’ve lived through a Wisconsin winter, you understand the appeal of this!
Not all sleep is created equal
There are two main sleep survival strategies that animals use in the winter. True hibernation is a voluntary state that animals enter induced by day length and hormone changes. These conditions indicate to an animal that it’s time to go into a truly deep, long sleep. Hibernation can last anywhere from several days to months depending on the species. Animals still need to wake up to drink water every one to three weeks. Waking up from hibernation every few weeks is a good idea to improve your immune system by removing those pesky parasites.
Torpor, similar to hibernation, is a sleep tactic animals use to survive the winter. Unlike hibernation, it is involuntary and induced by outside temperatures and food scarcity. Torpor can reduce an animal’s normal metabolic rate by 40 times in as short as two hours. In contrast to hibernation, torpor only lasts for a short period of time, sometimes just the night or day depending on the activity of the animal. Torpor can be considered “light hibernation”. To awake from torpor requires ample amounts of shivering and muscle contractions to return to a normal metabolic rate!
Torpor or hibernation?
Whether an animal goes into torpor or hibernation is usually based on body size. The smaller the body size, the more likely an animal is to enter into a state of hibernation over torpor. A large body requires removing higher levels of excess body heat which would make light bouts of torpor energy inefficient. Smaller bodied animals can adjust to winter conditions more quickly.
Based on what we now know about the differences between torpor and hibernation, can you take a guess as to what type of sleep the below animals use to get through the winter?
A. The black bear (Urus americanus) enters a state of TORPOR. Contrary to widespread belief, black bears go into torpor in the winter! They can turn their pee into protein through a urea recycling process and the females will wake up to give birth and go right back into a state of torpor! (source).
B. The chipmunk (Tamias spp.) uses HIBERNATION to survive the winter. A chipmunk can bring its heart rate down from 250 beats per minute (bpm) to as low as 4bpm.
C. Raccoons (Procyon lotor) enter into a state of TORPOR, along with species like skunks.
D. The common poorwill (Phalaenoptilus nuttallii), native to the western United States, is the only bird species known to truly hibernate in the winter (source). Birders may be familiar with their Wisconsin relative nightjars – the common nighthawk and eastern whip-poor-will!
One of the most incredible things about studying wildlife is that, no matter how much you think you know, something new and surprising will appear. Recently, I had the opportunity to review thousands of photos for an exciting project involving machine learning (which you can read more about in this blog post). A subset of the photos on my plate for review were of Virginia opossums (Didelphis virginiana).
Some might not draw a line between the words “exciting project” and “opossum,” but they truly are an interesting species. For starters, they are North America’s only marsupial, meaning females carry their offspring in a pouch, especially when the young are newly born (see the photo above). Additionally, those of us who live where ticks are a concern can thank opossums for consuming a fair number of these pests.
The first thing I learned about opossums from my time examining the photos is that they can vary widely in color. Above is a small collage of opossums that range in color from almost entirely white (known as leucism) to predominantly dark grey, although the animal pictured in the middle is more representative of Wisconsin’s majority.
Morphology, or the set of physical characteristics an animal displays, is not easily disguised in trail camera photos when compared to something fleeting, like behavior. Often, animals captured in the photos simply appear to be moving across the frame. This expectation is what led me originally to overlook a fascinating opossum behavior. As I flipped through the images, I noticed an infrared trigger in which the animal seemed to have debris stuck to its rear half. I imagined that it had gotten stuck in mud, but when I saw the phenomenon a second time – this time in daylight – I realized that this was no accident. In fact, these opossums were using their prehensile tails intentionally to carry bunches of leaves and twigs.
After doing some research on this behavior, I discovered that this has been documented before, albeit rarely. The consensus on the reason for this behavior is that opossums take their hauls to a temporary den site to use as bedding material. Of the over 3,000 opossum triggers that I was sorting, I only encountered nine in which this behavior was displayed. If I were to randomly choose a photo from the set, I would be more than twice as likely to encounter a raccoon misclassified as an opossum than I would be to have selected a photo of an opossum carrying leaves with its tail. Nine instances do not constitute a large enough sample size to do any major analyses. However, according to this photo set, there does not seem to be any obvious seasonality, with photos spread somewhat evenly from January 2017 through June 2018. Only one trigger was taken during the daytime – likely a product of opossums being primarily nocturnal.
If you stumble upon any interesting Snapshot photos – opossums or otherwise – please reach out to us. You can share them by using the “Talk” function on Zooniverse or by emailing them to DNRSnapshotWisconsin@wisconsin.gov.
Have you ever wondered what is responsible for the crimson shade of a fox’s coat, or the distinctive stripes that distinguish a raccoon tail? The answer, in short, is pigments! Pigments are chemical compounds that determine the color an object appears to the human eye based on how much light they absorb or reflect. Melanin is a major group of pigments naturally produced by most animals. Two types of melanin, eumelanin and pheomelanin, control the color that hair appears. This is true from the hair on your head to the coats of the critters you see in the wild!
While most species maintain the same coat coloration year-round, some swap out their coats seasonally for white, “ecologically fashionable” winter coats. This process is known as molting. You may recall some species around the world that do this, including Arctic fox (Vulpes lagopus), White-tailed ptarmigan (Lagopus leacura) and various weasel species. Changing coats is not only a terrific way to help avoid predation, but may also serve as an extra tool to keep warm during the frigid winter months. Because the white fur lacks pigment, it is believed that there is extra space in the hair shafts for air that can be warmed by the animal’s body heat (think of a bird ruffling its feathers during a cool morning to trap in warm air).
Although the exact mechanisms behind this wardrobe change are not fully understood, there is evidence that suggests that the length of daylight, also known as photoperiod, plays a key role in when animals switch their coat color. Receptors in the retina transfer messages to the brain that it’s time to get a new outfit for the next season. Once this process begins, the hair begins to change color starting with the extremities.
A local expert at swapping out coats is Wisconsin’s own Snowshoe hare (Lepus americanus). You can most commonly find these long jump champions in the northern forests of Wisconsin. Contrary to the common Cottontail rabbit, Snowshoe hare swap brown summer coats for bright white during the snowy winter months to camouflage with their surroundings.
Snapshot Wisconsin cameras capture images of Snowshoe hares year-round across the state. This provides a unique opportunity to not only pinpoint the time of year that snowshoes go through their wardrobe change, but also identify the surrounding area’s brown down or green up state. Because Snowshoe hares rely heavily on their coat color to stay camouflaged and avoid predation, any mismatch between coat and season can make a hare an easy target for lunch. Snapshot Wisconsin cameras can capture images of these mismatches to help understand interactions between Snowshoe hares and predation, as well as Snowshoe hare molting biology across time.
My brother Ian was a picky eater. Breakfast was always a bowl of Crispex. For lunch, he ate a PB&J and refused to eat the crusts. I was the opposite. Even as a young child, I loved proverbially “gross” foods like mushrooms and started drinking coffee when I was twelve.
Turns out that some animals are like Ian and some are like me. For example, monarch caterpillars only eat milkweed. We call animals like the monarch specialists. Conversely, some animals will eat, well, just about anything. Raccoons, for example, are equally happy eating crayfish from the creek or scraps from your garbage can. We call such species generalists.
Diet isn’t the only thing to be picky about! Some species exhibit preferences for precise habitat types. For example, the Kirtland’s Warbler breeds only in young jack pine barrens, primarily in Michigan, but also occasionally in Wisconsin. On the other hand, some species are ubiquitous. The coyote is an exemplar habitat generalist—you might spot one in the wilds of the Chequamegon-Nicolet National Forest or in a suburb of Milwaukee.
Taken together, diet and habitat comprise what we call the ecological niche of a species. You can think of a niche as the “cubbyhole” that a species occupies within the broader tapestry of its environment. The breadth of a niche is a continuum from extreme specialists (like Kirtland’s Warblers) to extreme generalists (like raccoons). Some species fall between those extremes; deer are a great example. Deer are strict herbivores, but they can be found in many different habits, from forests to farmlands. So, not every species can be neatly classified as a generalist or a specialist.
Scientists are interested in generalists and specialists because they exhibit different responses to change. Like a trained craftsman whose job is replaced by a machine, the specialist has nowhere to go when the environment changes. Generalists, on the other hand, can capitalize on the vacant niche space and colonize altered landscapes. Given the widespread changes humans are exerting on the earth, we are seeing global proliferation of generalists while many specialists are disappearing, a process known as biotic homogenization.
This may seem dire, but the more we learn about generalists and specialists, the more we’ll be able to do to maintain biodiversity and lose fewer specialists. In the meantime, I encourage you to think about the animals you see on a regular basis. Is that squirrel outside your window an ecological jack-of-all-trades? Are there any habitat specialists that live on your property? And maybe even think about your own niche—are you a generalist, a specialist, or somewhere in between?
From the Snapshot Wisconsin program, you may be familiar with wildlife monitoring using trail cameras. Trail cameras are one wildlife monitoring tool classified into a group of monitoring techniques that are considered non-invasive, meaning that the technique causes little or no impact on the animal’s normal activity, ecology or physiology. By contrast, invasive monitoring techniques include any type of wildlife monitoring that has a direct, human caused impact on an animal (GPS collaring, tagging, close observation are a few examples).
Tracking involves locating animal footprints and identifying the species. This monitoring technique can be done during all times of year in snow, mud, dirt or sand. You can learn a lot about an animal by its tracks. For example, you can tell what gait the animal was in (walk, trot, lope, spring), where it was heading to and from and if the animal was travelling in a group or alone.
Researchers can use tracks to estimate abundance, home ranges and behavior patterns. This can be especially helpful for monitoring more elusive animals that are sensitive to human disturbance.
One research project that uses tracks to estimate abundance is the Wisconsin winter wolf count. Using tracks in the snow, the DNR can estimate a minimum wolf count. For more information about that project, check out this link.
As we proceed through Wisconsin’s four seasons each year, you may appreciate the sight of colorful songbirds in springtime and notice the distinctive V-shape formation of Canada Geese as they fly south in the fall. These species are referred to as “migratory birds”, or populations of birds that travel from one place to another at regular times during the year.
Why do birds migrate?
Birds migrate in search of resources needed for their survival. Migratory birds primarily pursue sources of food or nesting locations to raise their young. In Wisconsin, we see an influx of bird species in springtime as warm weather returns and insect populations increase. As temperatures begin to drop in the fall, food supply dwindles and the birds fly south.
How do birds migrate?
Scientists believe there are many factors that trigger the migration of bird populations. Birds respond to changes in their environment such as day length, temperature, and availability of food resources. Additionally many birds go through hormonal changes with the arrival of new seasons. These hormonal shifts may affect your caged birds at home, you may recognize restless behavior in spring and fall. This restlessness around migratory periods is referred to as zugunruhe.
It isn’t fully understood how birds have developed such impressive navigation skills, but there are several factors that guide them. Birds can use directional information using the sun, stars, and even earth’s magnetic field. Landmarks, position of the setting sun, and even smell plays a role for various species.
How do scientists study migratory birds?
Several methods have been developed to track and study migratory birds including banding, satellite tracking, and by attaching geolocators to individuals. At Snapshot Wisconsin, trail cameras are now being added to the list of tools! Using preliminary data gathered from Zooniverse, the below slideshow shows the detections of Sandhill Cranes on Snapshot Wisconsin cameras throughout the year. The study of migration can be immensely beneficial for conservation efforts by pinpointing wintering and nesting locations to monitor potentially threatened or endangered populations.